Download Chapter 4 Elements and Symbols

Lecture Presentation
Chapter 4
Elements and
Symbols
Karen C. Timberlake
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chapter 4 Atoms and Elements
In addition to growing
crops and raising
animals, farmers must
understand how to
perform chemical tests
and how to apply
fertilizers and pesticides
or herbicides to crops.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chapter 4 Readiness
Key Math Skills
• Using Positive and Negative Numbers in Calculations (1.4B)
• Calculating Percentages (1.4C)
• Rounding Off (2.3)
Core Chemistry Skills
• Counting Significant Figures (2.2)
• Using Significant Figures in Calculations (2.3)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.1 Elements and Symbols
Elements
• are pure substances
from which all other
things are built.
• cannot be broken
down into simpler
substances.
• are listed on the inside
front cover of this text.
Learning Goal Given the name of an element, write its
correct symbol; from the symbol, write the correct name.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Some Elements and Their Names
Element names come from planets, mythological figures,
minerals, colors, geographic locations, and famous people.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chemical Symbols
Chemical symbols
• represent the names of the
elements.
• consist of one to two letters
and start with a capital letter.
One-Letter Symbols
C carbon
N nitrogen
F fluorine
O oxygen
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
Two-Letter Symbols
Co cobalt
Ca calcium
Al aluminum
Mg magnesium
© 2016 Pearson Education, Inc.
Names and Symbols of Common Elements
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chemical Symbols from Latin Names
Ag
silver (argentum)
Au
gold (aurum)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Write the correct chemical symbols for each of the following
elements:
A.
B.
C.
D.
E.
iodine
iron
magnesium
zinc
nitrogen
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Give the names of the elements with the following symbols:
A.
B.
C.
D.
E.
P
Al
Mn
H
K
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chemistry Link to Health: Toxicity of Mercury
Mercury (Hg)
• is a silvery, shiny element that is a liquid at room
temperature.
• can enter the body by mercury vapor inhalation, contact
with the skin, or ingestion of water or food contaminated
with mercury.
Once mercury has entered the body, it destroys proteins and
disrupts cell function. Long-term exposure can
• damage the brain and kidneys.
• cause mental retardation.
• decrease physical development.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chemistry Link to Health: Toxicity of Mercury
Mercury contamination comes from
• industrial wastes.
• fish and seafood.
• batteries.
• compact fluorescent bulbs.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.2 The Periodic Table
The periodic table
organizes 118
elements into groups
with similar properties
and places them in
order of increasing
atomic mass.
Learning Goal Use the periodic table to identify the group
and the period of an element; identify the element as a
metal, a nonmetal, or a metalloid.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Periodic Table of Elements
• First proposed by Russian Chemist Dmitiri Mendeleev in 1869
• Organized the known elements by similarities in physical and
chemical properties and then my increasing atomic “weights,” as
they were know back then. Today, we call it atomic mass
• Since 1915, the elements have been arranged by increasing
atomic number
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Periodic Table of Elements
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Groups and Periods
In the periodic table,
• elements are arranged according to properties.
• groups contain elements with similar properties in
vertical columns.
• periods are horizontal rows of elements, counted
from top to bottom of the table as Periods 1−7.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Groups and Periods
Vertical columns represent groups of elements, and horizontal
rows represent periods.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Group Numbers
Group numbers are written at the top of each vertical column.
• Use the letter A for representative elements
(Groups 1A–8A).
• Use the letter B for transition elements (Groups 3B–12B).
An alternative system uses numbers of 1–18 for all of the
groups, from left to right, across the periodic table.
Because both systems are currently in use, they are both
shown on the periodic table in this text and are included in our
discussions of elements and group numbers.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Group Names – some groups have common names
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Alkali Metals
Group 1A (1), the alkali
metals, includes the
following:
• lithium (Li)
• sodium (Na)
• potassium (K)
• rubidium (Rb)
• cesium (Cs)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Alkaline Earth Metals
Group 2A (2) elements, the alkaline
earth metals, are shiny but not as
reactive as Group 1A metals. They
include the following:
• beryllium (Be)
• magnesium (Mg)
• calcium (Ca)
• strontium (Sr)
• barium (Ba)
• radium (Ra)
Strontium gives the red color in fireworks.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Halogens
Group 7A (17), the
halogens, includes the
following:
• fluorine (F)
• chlorine (Cl)
• bromine (Br)
• iodine (I)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Noble Gases
Group 8A (18) is the noble gases, which include helium
(He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe)
and radon (Ra).
Noble gas elements are extremely unreactive (i.e. they
are seldom found in combination with other elements).
Were not discovered until the 1890s because of their
inactivity, so they were not on Mendeleev’s original
table
© 2013 Pearson Education, Inc.
Chapter 3, Section 2
23
Study Check
Identify the element described by each of the following groups
and periods:
1. Group 7A (17), Period 4
A. Br
B. Cl
C. Mn
2. Group 2A (2), Period 3
A. beryllium
B. boron
C. magnesium
3. Group 5A (15), Period 2
A. phosphorus
B. arsenic
C. nitrogen
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
3 Categories of Elements: Metals,
Nonmetals, and Metalloids
The heavy zigzag line separates metals and nonmetals.
• Metals are located to the left.
• Nonmetals are located to the right.
• Metalloids are located along the heavy zigzag line.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Characteristics of Metals, Nonmetals, and
Metalloids
Metals, except for hydrogen, located
on the left of the periodic table,
• are shiny and ductile, and conduct
heat and electricity.
• are solids, except for mercury
(Hg), which is a liquid.
Nonmetals, located on the right side
of the periodic table,
• are dull, brittle, and poor
conductors but often good
insulators.
• have low densities and melting
points.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Characteristics of Metals, Nonmetals, and
Metalloids
Metalloids, located along the heavy zigzag line on the
periodic table,
• exhibit properties of metals and nonmetals.
• are better conductors than nonmetals but not as
good as metals.
• are used as semiconductors and insulators,
because they can be modified to function as
conductors or insulators.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Comparing a Metal, a Nonmetal, and a
Metalloid
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Identify each of the following elements as a metal,
a nonmetal, or a metalloid:
A. sodium
B. chlorine
C. silicon
D. iron
E. carbon
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
List all of the elements that match the description.
A. metals in Group 4A (14)
Sn, Pb, C, Si, Ge
B. nonmetals in Group 5A (15)
Bi, N, P, As, Sb
C. metalloids in Group 4A (14)
C, Si, Ge, Sn, Pb
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.3 The Atom – A Brief History of Atomic Theory
An atom is the smallest
particle of an element that
retains the characteristics
of that element.
Aluminum foil contains
atoms of aluminum.
Learning Goal Describe the electrical charge and location in
an atom for a proton, a neutron, and an electron.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
John Dalton’s Atomic Theory ( circa 1808)
Dalton theorized that Atoms
 are tiny particles of matter
too small to see,
 are able to combine with
other atoms to make
compounds, and
 are similar to each other for
each element and different
from atoms of other
elements.
 A chemical reaction is the
rearrangement of atoms.
 Atoms are never created
or destroyed during
chemical and physical
changes
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 Dalton envisioned
atoms to be solid,
indivisible spheres, like
billiard balls  called the
“billiard ball model”
Chapter 3, Section 3
32
Atomic Theory in the late 1890’s
 Discovery of radioactivity and the discovery of
the first subatomic particle (the electron)
meant Dalton’s solid sphere model had to
change.
 JJ Thomson, discoverer of the electron,
developed “plum pudding model.”


Electron was tiny (1/2000th the size of the
atom), negatively charged particle
As atom electrically neutral, electron must be
embedded in “positive dough” of atom like
plums in plum pudding
© 2013 Pearson Education, Inc.
Chapter 3, Section 1
33
Electrical Charges in an Atom
Atoms contain the following
subatomic particles:
• protons that have a positive
(+) charge
• electrons that have a negative
(–) charge
• neutrons that have no charge
(neutral)
Like charges repel and unlike charges
attract.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
J. J. Thomson’s Cathode Ray Tube Exp
From his experiment, J. J. Thomson realized that
• cathode rays contain negatively charged particles.
• particles (now called electrons) have a much smaller mass
than the atom.
Thomson proposed a “plum-pudding” model of the atom in
which protons and electrons were randomly distributed in a
positively charged cloud, like plums in a pudding.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
J. J. Thomson’s Plum Pudding Model (1897)
Thomson’s “plum-pudding” model had protons
and electrons scattered throughout the atom.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Rutherford’s Gold Foil Experiment (1911)
In Rutherford’s gold foil experiment, positively charged
particles
• were aimed at atoms of gold.
• mostly went straight through the atoms.
• were deflected only occasionally.
Rutherford’s experiment concluded that there must be a small,
dense, positively charged nucleus in the atom that deflects
positive particles that come close.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Rutherford’s Gold Foil Experiment
(a) Positive particles are aimed at a piece of gold foil. (b) Particles that
come close to the atomic nuclei are deflected from their straight path.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Rutherford’s Nuclear Model of the
Atom (1911)
 The atom is mostly empty space
 All of the positive charge is located in a tiny,
dense nucleus
 The negative electrons are located at a
distance away and must be constantly
moving to avoid being pulled into the nucleus
39
© 2013 Pearson Education, Inc.
Chapter 3, Section 1
Discovery of Proton and Neutron
 Positive charge comes in nucleus actually
due to a particle, called the proton
(Rutherford, 1919)
 More mass in the nucleus than protons could
account for  in 1932, an electrically neutral
particle called the “neutron” was discovered
by James Chadwick.
40
© 2013 Pearson Education, Inc.
Chapter 3, Section 1
Structure of the Atom
An atom consists of
• a nucleus, located in the center of the atom, that
contains protons and neutrons and represents most of
the mass of an atom.
• electrons that occupy a large, empty space around the
nucleus.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Structure of the Atom
In an atom, the protons and neutrons that make up almost all the mass are
packed into the tiny volume of the nucleus. The rapidly moving electrons
(negative charge) surround the nucleus and account for the large volume
of the atom.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Mass of the Atom
Because the mass of subatomic particles is so small,
• chemists use a very small unit of mass called the atomic
mass unit (amu).
• 1 amu has a mass equal to 1/12 of the mass of the
carbon-12 atom that contains six protons and six neutrons.
• 1 amu = 1 Dalton (Da) in biology.
• Electrons have such a small mass that they are not
included in the mass of an atom.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Subatomic Particles in the Atom
Subatomic particles have a very small mass, and an
electron has a mass that is much less than that of a
proton or a neutron.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Which of the following subatomic particles fits each of the
descriptions below?
protons, neutrons, or electrons
A. found outside the nucleus
B. have a positive charge
C. have mass but no charge
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.4 Atomic Number and Mass Number
All atoms of an element
have the same number
of protons and the
same atomic number.
Learning Goal Given the atomic number and the mass
number of an atom, state the number of protons, neutrons,
and electrons.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atomic Number
The atomic number
• is a whole number specific for each element.
• is the same for all atoms of an element.
• is equal to the number of protons in an atom.
• appears above the symbol of an element in the
periodic table.
Atomic number
Symbol
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
11
Na
© 2016 Pearson Education, Inc.
Atomic Number = Protons in an Atom
Atomic number = number of protons—for example,
• the atomic number of H is 1; every H atom has one proton.
• the atomic number of C is 6; every C atom has six protons.
• the atomic number of Cu is 29; every Cu atom has 29 protons.
Core Chemistry Skill Counting Protons and Neutrons
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atomic Number = Protons in an Atom
All atoms of lithium (left) contain three protons, and all atoms of carbon (right) contain six protons.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atoms are Neutral
For neutral atoms, the net charge is zero.
number of protons = number of electrons
Aluminum has 13 protons and 13 electrons. The net (overall)
charge is zero.
13 protons (13+) + 13 electrons (13–) = 0
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Use the periodic table to fill in the atomic number, number of
protons, and number of electrons for each of the following
elements:
Element Atomic
Number
N
Protons
Electrons
Zn
S
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Mass Number
The mass number
• represents the number of particles in the nucleus.
• is equal to the number of protons + the number of neutrons.
• is always a whole number.
• does not appear in the periodic table.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Composition of Some Atoms of Different
Elements
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Tips: Protons and Neutrons
Number of protons = atomic number
Number of protons + neutrons = mass number
Number of neutrons = mass number – atomic number
Note: Mass numbers are given for specific isotopes only.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
An atom of lead (Pb) has a mass number of 207.
A. How many protons are in the nucleus?
B. How many neutrons are in the nucleus?
C. How many electrons are in the atom?
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.5 Isotopes and Atomic Mass
24
12
Mg
The atomic symbol for
an isotope of magnesium
with 12 neutrons.
Learning Goal Determine the number of protons, electrons,
and neutrons in one or more of the isotopes of an element;
calculate the atomic mass of an element using the percent
abundance and mass of its naturally occurring isotopes.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Isotopes
Isotopes
• are atoms of the same element.
• have different mass numbers.
• have the same number of protons but different numbers
of neutrons.
• can be distinguished by their atomic symbols.
Core Chemistry Skill Writing Atomic Symbols for Isotopes
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atomic Symbols: Subatomic Particles
Given the atomic symbols, determine the number of protons,
neutrons, and electrons.
16
8
O
31
15
P
65
30
ANALYZE
THE PROBLEM
Zn
Atomic
Number
number in
lower left
corner
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
Mass
Number
number in
upper left
corner
Number of
Protons
equal to
atomic
number
© 2016 Pearson Education, Inc.
Atomic Symbols: Subatomic Particles
Determine the number of protons, neutrons, and electrons.
Isotope
Atomic
Number
Mass
Number of Number of
O
Number Protons
Neutrons
16
8
16
8
31
15
O
8
16
8
8 (16–8)
P
15
31
15
16 (31–16)
65
30
Zn
30
65
30
35 (65–30)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Isotopes of Magnesium
Magnesium, with three
naturally occurring
isotopes, has an atomic
mass of 24.31 amu.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Isotopes of Magnesium
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Naturally occurring carbon consists of three isotopes: 12C,
13C, and 14C. State the number of protons, neutrons, and
electrons in each of the three isotopes.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Write the atomic symbols for atoms with the following
subatomic particles:
A. 8 protons 8 neutrons 8 electrons
B. 17 protons 20 neutrons 17 electrons
C. 47 protons 60 neutrons 47 electrons
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
1. Which of the pairs below are isotopes of the same
element?
2. In which of the pairs below do both atoms have eight
neutrons?
A.
15
8
B.
12
6
C.
15
7
X
15
7
X
X
14
6
X
X
16
8
X
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Calculating Average Atomic Mass
Atomic mass is the
• weighted average of all
naturally occurring
isotopes of that element.
• number on the periodic
table below the chemical
symbol.
Chlorine, with two naturally
occurring isotopes, has an
atomic mass of 35.45 amu.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Calculating Average Atomic Mass
To calculate atomic mass,
• use the experimental percent abundance of each isotope of
the element.
• multiply the percent abundance by the atomic mass of that
isotope.
• sum the total mass of all isotopes.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Calculating Average Atomic Mass
To calculate atomic mass of chlorine, use experimental data
for both isotopes.
Atomic mass of Mg = 18.88 amu + 2.531 amu + 2.902 amu
= 24.31 amu (weighted average mass)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Average Atomic Masses of Some Elements
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Lithium consists of two naturally occurring isotopes, 6Li and
7Li. Use the periodic table to predict which isotope is the
more prevalent one. (According to the periodic table, the
atomic mass of lithium is 6.941 amu.)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Gallium is an element found in lasers used in compact disc
players. In a sample of gallium, there is
60.10% of 69Ga (atomic mass 68.926) atoms
39.90% of 71Ga (atomic mass 70.925) atoms
What is the atomic mass of gallium?
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.6 Electron Energy Levels
A rainbow forms when
light passes through
water droplets.
Learning Goal Describe the energy levels, sublevels, and
orbitals for the electrons in an atom.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electromagnetic Radiation
We experience electromagnetic radiation in different forms,
such as light, the colors of a rainbow, or X-rays.
Electromagnetic radiation consists of energy particles that
move as waves of energy.
• The distance between the peaks of waves is called the
wavelength.
• High-energy radiation has shorter wavelengths.
• Low-energy radiation has longer wavelengths.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atomic Spectrum
When light from a heated element passes through a
prism, it separates into distinct lines of color separated
by dark areas called an atomic spectrum.
Each element has its own unique atomic spectrum.
In an atomic spectrum, light from a heated element separates into distinct lines.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
The Bohr Model (1913)
 Proposed by Danish physicist Niels Bohr
 Problems with Rutherford’s model as
conflicted with laws of physics
 Bohr proposed new laws were needed for tiny
particles like electrons  led to development
of quantum physics
 Bohr’s model solved some of these problems
 Main ideas  electrons can only have certain
allowable energies, which correspond to
different distances from the nucleus = Energy
Levels
74
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Chapter 3, Section 1
The Bohr Model (1913)
 Energy levels radiate away from nucleus
 Energy levels are labeled by what is called
the principal quantum number “n”
 Each holds a distinct number of electrons
which corresponds to 2n2



n = 1 holds 2(1)2 = 2 electrons
n = 2 holds 2(2)2 = 8 electrons
n = 3 holds 2(3)2 = 18 electrons
75
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Chapter 3, Section 1
Electron Energy Levels
The lines in an atomic spectrum are associated with the
changes in energies of the electrons.
In an atom, each electron has a specific energy, known as its
energy level, which
• is assigned principal quantum numbers (n) = (n = 1,
n = 2, …).
• increases in energy as the value of n increases and
electrons are farther away from the nucleus.
The energy of an electron is quantized—electrons can have
only specific energy values.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electromagnetic Spectrum
The electromagnetic spectrum shows the arrangement of
wavelengths of electromagnetic radiation, with the visible range
from 700 to 400 nm.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electrons and Energy Levels
• Electrons with the same
energy are grouped in the
same energy level.
• Energy levels are assigned
values called principal
quantum numbers (n),
(n = 1, n = 2, …).
An electron can have only the
energy of one of the energy
levels in an atom.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Changes in Electron Energy Level
• Electrons move to a
higher energy level
when they absorb
energy.
• When electrons fall
back to a lower energy
level, light is emitted.
• The energy emitted or
absorbed is equal to
the differences
between the two
energy levels.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
The Bohr Model (1913)
80
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Chapter 3, Section 1
Problem with Bohr Model
 Only worked for H atom
 Historically important model because:



it was the first to say different laws of physics
needed  led to development of quantum
theory, or quantum physics
It was the first to suggest that electrons can
only have certain, allowable energies (energy
of the electron is quantized)
Still use energy levels today
81
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Chapter 3, Section 1
Modern Atomic Theory
 Based on Quantum Physics (developed in the




1920s)
Treats the electron as both a particle and a
standing wave (yikes!, what does that mean?)
the electron can have only certain allowable
energies (e- energy is quantized) which
correspond to different distances from the
nucleus = energy levels
Solutions to the math equations of quantum
physics provide the most probable region
around the nucleus of finding an electron.
These “probability regions” are also known as
orbitals
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Chapter 3, Section 1
82
Modern Model of the Atom
Called electron cloud model
 Today, we can see the
surfaces of atoms
 Device used is based on the
wave properties of electrons
(electron microscopes based
on the wave properties of
electrons, have very tiny
wavelength, so can see very
tiny things)
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Images of nickel atoms
are produced when nickel is magnified
millions of times by a scanning
tunneling microscope (STM). This
instrument generates an image of
the atomic structure.
Chapter 3, Section 3
83
Models of the Atom Between 1808 and Now
84
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Chapter 3, Section 1
Energy Sublevels and The Quantum Mechanical Model
The result of the quantum mechanical model (a
mathematical model) is that energy levels are split into
sublevels.
It is the arrangement of electrons that determines the
physical and chemical properties of an element.
• Each energy level consists of one or more sublevels.
• The number of sublevels in an energy level is equal to the
principal quantum number n of that energy level.
• The sublevels are identified as s, p, d, and f.
• The order of sublevels in an energy level is
s<p<d<f
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Sublevels
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
s Orbitals
The location of an electron
is described in terms of
probability.
• Orbitals are a threedimensional volume in
which electrons have the
highest probability of
being found.
• The s orbitals are shown
as spheres.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
(a) The electron cloud of an s orbital
represents the highest probability of
finding an s electron. (b) The s orbitals
are shown as spheres. The sizes of the
s orbitals increase because they contain
electrons at higher energy levels.
© 2016 Pearson Education, Inc.
p Orbitals
There are three p orbitals,
starting with n = 2.
• Each p orbital has two
lobes, like a balloon tied
in the middle, and can
hold a maximum of two
electrons.
• The three p orbitals are
arranged perpendicular to
each other along the x, y,
and z axes around the
nucleus.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
p Orbitals
A p orbital has two regions of high probability, which gives a “dumbbell” shape. (a)
Each p orbital is aligned along a different axis from the other p orbitals. (b) All three p
orbitals are shown around the nucleus.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
d Orbitals
Each of the d sublevels contains five d orbitals.
Four of the five d
orbitals consist of four
lobes that are aligned
along or between
different axes. One d
orbital consists of two
lobes and a doughnutshaped ring around its
center.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Orbital Capacity and Electron Spin
The Pauli exclusion principle states that
• each orbital can hold a maximum of two electrons.
• electrons in the same orbital repel each other.
• electrons in the same orbital must have their magnetic spins
cancel (they must spin in opposite directions).
We can represent magnetic spins with an arrow
An orbital can hold up
to two electrons with
opposite spins.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Number of Electrons in Sublevels
There is a maximum number of electrons that can fill each
sublevel.
• Each s sublevel has one orbital and can hold a maximum
of two electrons.
• Each p sublevel has three orbitals and can hold a
maximum of six electrons.
• Each d sublevel has five orbitals and can hold a maximum
of 10 electrons.
• Each f sublevel can has 7 orbitals and can hold a
maximum of 14 electrons.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Number of Electrons in Sublevels
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Which of the following elements are likely to have electrons
in the 3p sublevel?
C
Si
O
As
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.7 Electron Configurations
Electron configurations follow the order of occupied sublevels
on the periodic table.
Learning Goal Draw the orbital diagram and write the
electron configuration for an element.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Orbital Diagrams
Orbital diagrams use boxes to show how electrons
• are arranged in the orbitals of an atom.
• fill the orbitals and energy levels from lowest to highest
energy level.
• fill orbitals within the same sublevel one at a time, before
pairing the electrons.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electron Configurations
Chemists use a notation called electron configuration to
• indicate the placement of electrons in an atom.
• show how electrons fill energy levels and sublevels in order
of increasing energy.
• write an abbreviated form using a noble gas to represent all
electrons preceding it.
Electron Configuration for Carbon
Core Chemistry Skill Writing Electron Configurations
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Period 1: Hydrogen and Helium
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Period 2: Lithium to Neon
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Guide to Drawing Orbital Diagrams
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Drawing Orbital Diagrams
Nitrogen atoms are found in amino acids, proteins, and
nucleic acids. Draw the orbital diagram for nitrogen.
STEP 1 Draw boxes to represent the occupied
orbitals.
Nitrogen’s atomic number is 7, which means it has seven
electrons. For the orbital diagram, we draw boxes to
represent the 1s, 2s, and 2p orbitals.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Drawing Orbital Diagrams
Nitrogen atoms are found in amino acids, proteins, and
nucleic acids. Draw the orbital diagram for nitrogen.
STEP 2 Place a pair of electrons with opposite spins
in each filled orbital.
First we place a pair of electrons with opposite
spins in the1s and 2s orbitals.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Drawing Orbital Diagrams
Nitrogen atoms are found in amino acids, proteins, and
nucleic acids. Draw the orbital diagram for nitrogen.
STEP 3 Place the remaining electrons in the last
occupied sublevel in separate orbitals.
Place three remaining electrons in the three
separate 2p orbitals, with arrows drawn in the
same direction.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Period 3: Sodium to Argon
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electron Configurations and the
Periodic Table
The electron configurations of elements are related to their
positions on the periodic table. Different sections or blocks
correspond to sublevels s, p, d, and f.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Blocks on the Periodic Table
1. The s block contains elements in Groups 1A (1) and 2A
(2). This means the final one or two electrons are in the s
sublevel.
2. The p block consists of elements in Group 3A (13) to
Group 8A (18). There are six p block elements in each
period, because three p orbitals can hold a maximum of six
electrons.
3. The d block, which contains transition elements, first
appears after calcium (atomic number 20). There are
10 elements in the d block, because five d orbitals can hold
a maximum of 10 electrons.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Blocks on the Periodic Table
4. The f block, the inner transition elements, is the two rows
of elements at the bottom of the periodic table. There are
14 elements in each f block, because seven f orbitals can
hold a maximum of 14 electrons.
Core Chemistry Skill Using the Periodic Table to Write
Electron Configurations
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Guide to Writing Configurations Using
Sublevel Blocks
Use the sublevel blocks on the periodic table to write the electron
configuration for chlorine.
STEP 1 Locate the element on the periodic table.
Chlorine (atomic number 17) is in Group 7A (17)
and Period 3.
STEP 2 Write the filled sublevels in order, going across
each period.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Guide to Writing Configurations Using
Sublevel Blocks
Use the sublevel blocks on the periodic table to write the
electron configuration for chlorine.
STEP 3 Complete the configuration by counting the
electrons in the last occupied sublevel block.
Because chlorine is the fifth element in the 3p
block, there are five electrons in the 3p sublevel.
The electron configuration for chlorine (Cl) is
1s22s22p63s23p5.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electron Configurations: Period 4 and
Above
Beginning in Period 4,
• the 4s sublevel fills before the 3d sublevel, because the 3d
sublevel is slightly lower in energy than the 4s sublevel.
• the 5s sublevel fills before the 4d sublevel.
• the 6s sublevel fills before the 5d sublevel.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electron Configurations: Period 4 and
Above
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Electron Configurations: Period 4 and
Above
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Use the sublevel blocks on the periodic table to write the
electron configuration for selenium.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
Use the sublevel blocks on the periodic table to write the
electron configuration for selenium.
STEP 1 Locate the element on the periodic table.
Selenium is in Period 4, Group 6A (16).
STEP 2 Write the filled sublevels in order, going across
each period.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
Use the sublevel blocks on the periodic table to write the
electron configuration for selenium.
STEP 3 Complete the configuration by counting the
electrons in the last occupied sublevel block.
Because selenium is the fourth element in the 4p
block, there are four electrons to place in the 4p
sublevel.
The electron configuration for selenium (Se) is
1s22s22p63s23p64s23d104p4.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
3d Sublevel Exceptions
• For chromium (Cr), moving one of the 4s electrons to the
3d sublevel adds stability with a half-filled d subshell, and
the resulting configuration is 4s13d5.
• For copper (Cu), moving one of the 4s electrons to the 3d
sublevel adds stability with a filled d subshell, and the
resulting configuration is 4s13d10.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Use the periodic table to give the symbol and name for the
element with the electron configuration of
1s22s22p63s23p64s23d7.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
Use the periodic table to give the symbol and name for the
element with the electron configuration of
1s22s22p63s23p64s23d7.
There are seven electrons in the 3d sublevel. Thus, the
element is cobalt (Co).
1
2
3
Sc Ti
V
4
5
6
7
Cr Mn Fe Co Ni
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
Cu Zn
© 2016 Pearson Education, Inc.
Study Check
Write the electron arrangement for the following elements:
C
Si
O
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
STEP 1 Locate the element on the periodic table.
C: atomic number 6, Period 2, Group 4A (14)
Si: atomic number 14, Period 3, Group 5A (15)
O: atomic number 8, Period 2, Group 6A (16)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
STEP 2 Write the filled sublevels in order, going across
each period.
C
1s22s2
Si 1s22s22p63s2
O 1s22s2
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
STEP 3 Complete the configuration by counting the
electrons in the last occupied sublevel block.
C, the second element in the 2p block, has two
electrons to place in the 2p sublevel: 1s22s22p2.
Si, the second element in the 3p block, has two
electrons to place in the 3p sublevel:
1s22s22p63s23p2.
O, the fourth element in the 2p block, has four
electrons to place in the 2p sublevel: 1s22s22p4.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
4.8 Trends in Periodic Properties
The atomic size of representative elements is affected by the
attractive forces between the protons in the nucleus and the
electrons in the outermost energy level.
Learning Goal Use the electron configurations of elements
to explain the trends in periodic properties.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Group Numbers: Valence Electrons
• For representative elements in Groups 1A (1)–8A (18),
chemical properties are due to the number of valence
electrons.
• Valence electrons are the number of electrons in the
outermost energy level.
• The group number gives the number of valence electrons
for the representative elements.
Core Chemistry Skill Identifying Trends in Periodic
Properties
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Valence Electron Configurations
Valence Electron Configuration for Representative Elements
in Periods 1 to 4
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Using the periodic table, write the group number, the period,
and the valence electron configuration for the following:
A. calcium
B. lead
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
The valence electrons are the outermost s and p electrons.
Although they may have electrons in the d or f sublevel, they
are not valence electrons.
A. Calcium is in Group 2A (2), Period 4. It has a valence
electron configuration of 4s2.
B. Lead is in Group 4A (14), Period 6. It has a valence
electron configuration of 6s26p2.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Lewis Symbols
Lewis symbols represent the valence electrons as dots
placed on sides of the symbol for an element.
• One to four valence electrons are arranged as single dots.
• Five to eight valence electrons are arranged with at least
one pair of electrons around the symbol for the element.
Lewis Symbols for Magnesium
Core Chemistry Skill Drawing Lewis Symbols
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Lewis Symbols
Lewis Symbols for Selected Elements in Periods 1 to 4
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Write the electron-dot symbol for each of the following
elements: Cl, C, N.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
Write the electron-dot symbol for each of the following
elements: Cl, C, N.
Cl
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
C
N
© 2016 Pearson Education, Inc.
Atomic Size
Atomic size
• is determined by the atom’s atomic radius, the distance
between the nucleus and the outermost electrons.
• increases for representative elements from top to bottom
of the periodic table.
• decreases within a period as a result of increased
number of protons in the nucleus.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Atomic Size
For representative elements, the atomic size increases
going down a group but decreases going from left to right
across a period.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Ionization Energy
Ionization energy is the energy required to remove one of the
outermost electrons.
Na(g) + energy (ionization)  Na+(g) + e−
• As the distance from the nucleus to the valence electrons
increases, the ionization energy decreases.
• The ionization energy is low for metals and high for the
nonmetals.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Ionization Energy
Ionization energy decreases
down a group and increases
going across a period from left
to right.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Metallic Character
An element with metallic character is one that loses valence
electrons easily.
Metallic character
• is more prevalent in metals on the left side of the
periodic table.
• is less for nonmetals on the right side of the periodic table
that do not lose electrons easily.
• decreases going down a group, as electrons are farther
away from the nucleus.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Metallic Character
The metallic character
of the representative
elements increases
going down a group
and decreases going
from left to right
across a period.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Summary of Trends in the Periodic Table
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Given the elements C, N, and Cl,
A. which is the largest atom?
B. which has the highest ionization energy?
C. which belongs to Group 5A (15)?
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.