Download 5.2 The Modern Periodic Table

REVIEW FROM CHAPTER 4
n  Atomic
Number =
n  Number of Electrons =
n  Mass Number =
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Chapter 5: The Periodic Table
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REVIEW FROM CHAPTER 4
n  Atomic
Number = # of Protons
n  Number of Electrons = # of Protons
n  Mass Number = Neutrons + Protons
n  Mass Number = Neutrons + Atomic #
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Chapter 5: The Periodic Table
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REVIEW FROM CHAPTER 4
n  #
of Protons = Atomic #
n  # of Electrons = # of Protons = Atomic #
n  # of Neutrons = Mass # - Atomic #
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Chapter 5: The Periodic Table
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5.2 THE MODERN PERIODIC
TABLE
n 
Vocabulary: period, group, periodic law, atomic mass
unit (amu), metals, transition metals, nonmetals
n 
Objectives:
n  Describe the arrangement of elements in the
modern periodic table.
n  Explain how the atomic mass of an element is
determined and how atomic mass units are
defined.
n  Identify general properties of metals, nonmetals,
and metalloids.
n  Describe how properties of elements change
across a period in the periodic table.
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Chapter 5: The Periodic Table
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THE PERIODIC LAW
n 
Mendeleev developed periodic table before
discovery of protons.
n 
Modern periodic table, elements are arranged
by increasing atomic number.
Uses of modern periodic table of elements:
classify elements & compare properties
n 
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MODERN PERIODIC TABLE OF ELEMENTS
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Chapter 5: The Periodic Table
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PERIODS
THE PERIODIC LAW: PERIODS
period - each row on periodic table of elements
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CHAPTER 4 REVIEW: ENERGY
LEVELS & ORBITALS
n 
Energy levels - possible energies that
electrons in an atom can have
n 
Orbital - region of space around nucleus where
an electron is likely
to be found
n 
Each orbital can
contain 2 electrons
at most.
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Chapter 5: The Periodic Table
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THE PERIODIC LAW: PERIODS
n 
# of elements per period varies because # of
available orbitals increases from energy level
to energy level.
n 
To understand structure of table, think about
what happens as atomic number increases.
n  atomic number = # of protons
n  How does this relate to # of electrons in an
atom?
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THE PERIODIC LAW: PERIODS
n 
1st energy level has only
1 orbital (therefore, only
holds 2 electrons).
n 
Hydrogen (H) & Helium (He) can fit
in this energy level.
n  Hydrogen (H) atom 1 electron.
n 
Hydrogen (H)
Helium (He) atom
2 electrons
Helium (He)
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THE PERIODIC LAW: PERIODS
n 
Lithium (Li)
n  3 electrons.
n  1 of 3 electrons must be
in 2nd energy level
n  1st element in Period 2.
n 
Sodium (Na)
n  11 electrons.
n  1 electron in its 3rd energy level.
n  1st element in Period 3.
Link: http://web.visionlearning.com/custom/chemistry/animations/CHE1.3-an-atoms.shtml
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THE PERIODIC LAW: PERIODS
n 
This pattern applies to all elements in first
column of table.
1. Hydrogen (H)
2. Lithium (Li)
3. Sodium (Na)
4. Potassium (K)
5. Rubidium (Rb)
6. Cesium (Cs)
7. Francium (Fr)
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THE PERIODIC LAW: PERIODS
n 
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The elements that start off each row on the
Periodic Table (H, Li, Na, K Rb, Cs and Fr)
also start off each of the seven main energy
levels.
Chapter 5: The Periodic Table
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THE PERIODIC LAW: PERIODS
n 
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Elements that start off each row also start off
each of the 7 main energy levels.
Chapter 5: The Periodic Table
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THE PERIODIC LAW: GROUPS
GROUPS
group - each column on periodic table of elements
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THE PERIODIC LAW: GROUPS
n 
Elements within a group have similar electron
configurations & therefore similar chemical
properties.
n 
Properties of elements repeat in a predictable
way when atomic numbers are used to arrange
elements into groups.
n 
Periodic law - pattern of repeating properties
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ATOMIC MASS
There are 4 pieces of information for each element.
17
Symbol
Cl
Chlorine
Atomic Mass
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35.453
Chapter 5: The Periodic Table
Atomic Number
Name of the
element
17
ATOMIC MASS
n 
Atomic mass is a value that depends on
1. distribution of an element s isotopes in nature
2. masses of those isotopes
17
Cl
Chlorine
Atomic Mass
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35.453
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ATOMIC MASS:
ATOMIC MASS UNITS
n 
1 isotope is chosen to serve as standard for
element.
n 
Scientists assigned 12 atomic mass units to
carbon-12 atom (6 protons + 6 neutrons).
n 
atomic mass unit (amu) - one twelfth the
mass of a carbon-12 atom.
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ATOMIC MASS:
ISOTOPES OF CHLORINE
n 
In nature, most elements exists as a mixture of 2
or more isotopes.
n 
2 natural isotopes of chlorine:
n  Chlorine-35
(17 protons + 18 neutrons)
n  Chlorine-37
(17 protons + 20 neutrons)
Unit understood
to be in amu
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Chapter 5: The Periodic Table
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Cl
Chlorine
35.453
20
ATOMIC MASS:
WEIGHTED AVERAGES
Weighted Averages to Determine Grade
n 
Tests…………………………………………………………. 25 %
n 
Labs…………………………………….…...…………......... 20 %
n 
Quizzes (and Do Now) ………………………………….... 15 %
n 
Homework ………………………………………………….. 15 %
n 
Class Participation…………………….……..…………….. 10 %
n 
Binder Checks ……………………………………………... 05 %
n 
Other ……………………………………….……................ 10 %
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ATOMIC MASS:
WEIGHTED AVERAGES
n 
2 natural isotopes of chlorine:
n  Chlorine-35
n  Chlorine-37
n 
If you find the average of these 2 ((35+37)/2) it
would equal 35.967, not 35.453.
n 
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The atomic mass value of Cl in
the periodic table is a
weighted average.
Chapter 5: The Periodic Table
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Cl
Chlorine
35.453
22
ISOTOPES OF CHLORINE
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THE MODERN PERIODIC TABLE OF
ELEMENTS (FROM TEXTBOOK)
Presents different ways to classify elements.
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CLASSES OF ELEMENTS
1. solids, liquids, or gases based on their states of
matter at room temperature (23°C).
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Gases
Solids
Liquids
1
6
80
H
C
Hg
Hydrogen
1.079
Carbon
12.011
Mercury
200.59
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CLASSES OF ELEMENTS
2. Elements divided into those that occur
naturally & those that do not.
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n 
Atomic #s 1-92 occur on Earth (except Tc & Pm).
n 
Atomic #s 93 & higher do not occur
naturally.
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CLASSES OF ELEMENTS
3.
Elements placed
into categories
based on their
general properties
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Elements are classified as
n  Metals (Left)
n  Nonmetals (Right)
n  Metalloids (Middle)
Chapter 5: The Periodic Table
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CLASSES OF ELEMENTS:
METALS (Blue Boxes)
n 
Metals - elements that are good conductors of electric
current & heat.
n 
Majority of elements
n 
Most/many metals are
n 
n 
n 
n 
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solids at room temperature (except Hg)
malleable
ductile (can be drawn into thin wires)
Some extremely reactive, some do not react easily.
n  i.e. Gold (Au) remains shiny (doesn t react w/ O)
but magnesium (Mg) quickly dulls (reacts w/ O).
Chapter 5: The Periodic Table
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CLASSES OF ELEMENTS:
METALS – TRANSITION METALS
n 
Transition metals are elements that form a
bridge between elements on left & right sides of
table. Groups 3-12.
n 
Examples: Cu & Ag.
n 
1 property of transition metals:
n  Ability to form compounds
with distinctive colors.
n  i.e. compound of erbium
& oxygen used to tint lenses.
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CLASSES OF ELEMENTS:
NONMETALS (Yellow Boxes)
n 
Nonmetals - elements that are poor
conductors of heat & electric current
n 
Examples: He, C, Cl, S
n 
Low boiling points à many gases at room
temperature. i.e. N & O
n 
Solid at room temperature tend to be brittle.
n 
Vary in chemical and physical properties.
n  i.e. reactive (fluorine) to not reactive
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CLASSES OF ELEMENTS:
METALLOIDS (Green Boxes)
n 
Metalloids - elements with properties that fall
between those of metals and nonmetals.
Metals
Good Conductors
of Electric
Current
n 
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Metalloids
Varies with
temperature
Nonmetals
Poor
Conductors of
Electric Current
Examples: Pure silicon (Si) & Germanium (Ga) are
good insulators at low temperatures & good
conductors at high temperatures.
Chapter 5: The Periodic Table
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VARIATION ACROSS A PERIOD
n 
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Across a period from left to right, the elements
become less metallic & more nonmetallic in
their properties.
Chapter 5: The Periodic Table
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REVIEW
n 
Name & describe 3 categories that are used to
classify the elements in the periodic table (based
on their general properties).
n 
Which type of metals tend to form compounds
with distinctive colors?
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REVIEW
n 
Name & describe 3 categories that are used to
classify the elements in the periodic table (based
on their general properties).
n 
n 
n 
n 
Which type of metals tend to form compounds
with distinctive colors?
n 
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Metals
Nonmetals
Metalloids
Transition metals
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LINKS
n 
David s Wizzy Periodic Table - Click on Element to See
Atom Structure.
http://www.colorado.edu/physics/2000/applets/a2.html
n 
Interactive Periodic Table of Elements.
http://www.webelements.com/
http://www.chemicool.com/ http://web.visionlearning.com/
custom/chemistry/custom/CHE1.4-pg-table.shtml
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