Download Atomic Structure & the Periodic Table CHAPTERS 4 & 5

Atomic Structure & the
Periodic Table
CHAPTERS 4 & 5
Objectives
Understandings:
 Chemical structure determines the
properties of matter

The identity and properties of individual
elements is determined by its Atomic
number (protons).

The relative locations on periodic table
are connected with chemical reactivity
Students Will Know:
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
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
Essential Question(s):
What is the arrangement of subatomic particles in
an atom and how does this affect the formation of
compounds?
How is the periodic table arranged and what
patterns are present?
How does particle size of a substance affect its
properties? (macro, micro, vs. nano)
How does the location of an element on the periodic
table help determine its reactivity?
Students will be able to:
 Draw an atom with correct placement of electrons,
The currently accepted model of the atomic
protons, neutrons based on Modern Atomic Theory
structure
 Differentiate between an ion, isotope, and neutral
The difference between the atomic mass and the
atoms
atomic number
 Recognize the periodic table’s organization by
The size and scale of atomic particles
atomic number, electron level, and similar
The difference between a group and a period of
characteristics of elements
the periodic table
 Determine the atomic mass and atomic number for
the common elements using the periodic table and
be able to predict the placement of an unknown
element.
Websites
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www.sciencespot.net/Pages/kdzchem.html
www.chem4kids.com/files/atom_intro.html
www.sciencespot.net/Pages/kdzchem2.html
Chapter 4: Atomic Structure

What I need to know:
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Be able to compare and
contrast the different
theories of atomic structure
Know the basic properties,
size, function, and location
of the 3 subatomic particle
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Neutron, Proton, Electron
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Use the periodic table and
diagrams to determine the
atomic number and the
mass number of an element
Understand the difference
between a neutral atom,
isotope, and ion
Understand Modern
Atomic Theory
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Energy levels
Electron cloud model
Atomic orbitals and electron
configuration (p118)
The Atom Song
The History of Atomic Structure
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Greeks - Democritus
Dalton
Thomson
Rutherford
Bohr
Modern Atomic Theory
The Models
Greeks
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Democritus – the first to
name the atom
hypothesized that all matter
is composed of tiny
indestructible units, called
atoms.
atoms themselves remain
unchanged, but move about
in space to combine in
various ways to form all
objects
Thomson

1897- discovered the first component part of the atom: the
electron, a particle with a negative electric charge. J.J.
Thomson suggested the"plum pudding" model. In this model
the electrons and protons are uniformly mixed throughout the
atom:
Rutherford
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Discovers the Atoms Nucleus
Stated that the atom as has a
central positive nucleus
surrounded by negative orbiting
electrons.
This model suggested that most
of the mass of the atom was
contained in the small nucleus,
and that the rest of the atom was
mostly empty space.
Rutherford - Gold Foil Experiment


This experiment involved the firing of radioactive
particles through minutely thin metal foils (notably
gold) and detecting them using screens coated with
zinc sulfide (a scintillator).
Rutherford found that although the vast majority of
particles passed straight through the foil
approximately 1 in 8000 were deflected leading him
to his theory that most of the atom was made up of
'empty space'.
Neils Bohr


This model was
proposed by Niels
Bohr in 1915;
it is not completely
correct, but it has many
features that are
approximately correct.

Often called the
planetary model (but it
is not that simple)
Bohr
This shows a Bohr model
 Electrons are in energy
shells or levels
 2 in the first
 8 in the 2nd
 18 in the 3rd
 Never, more than 8 in the
outer most shell
 Outer most are called
Valence electrons

Electron Cloud Model (1920's)
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
An atom consists of a
dense nucleus composed of
protons and neutrons
surrounded by electrons
that exist in different
clouds at the various
energy levels.
The correct theory of the
atom is called quantum
mechanics; the Bohr Model
is an approximation to
quantum mechanics.
The Electron Cloud model
is a more realistic model
Atomic Structure Practice
Worksheet Packet:
• Counting Atoms WS
• Drawing Atoms
• Atomic Dimensions
• Atomic Math
• Using the Periodic Table to get info on
Atoms
Atomic Structure
http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm

Proton
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Carries a positive charge and is found in the
nucleus
The atomic number and number of protons in an
atom is always the same
The atomic number identifies what the element is
on the periodic table
Example: Oxygen has an atomic number of 8 so
it has 8 protons in its nucleus
Neutrons
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Found in the nucleus
They are neutral and do not carry an electrical
charge
The number of neutrons can vary within the
element, but when they do, the element
becomes an isotope
Electrons
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Electrons carry a negative charge
They are found outside the nucleus
They are very small compared to the protons and
neutrons
They are found in energy levels moving around the
nucleus – but they may be in any area of the electron
cloud
Elements bond with other elements at the electron
level
The Size of the Nucleus

In the drawings above, the nucleus is too large. Or,
put another way, if the nucleus is going to be that
large, the electrons are too close. Real atoms are
mostly empty space. If we wanted our drawings to
be accurate, we would have to place the electrons
about a mile away. Clearly, it would be difficult to
bring a drawing that large to class.
Isotopes
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Isotopes
Isotopes are atoms of the same element that have
different numbers of neutrons in the nucleus.
Remember that it is only the number of protons that
determines the identity of an element.
Let's look at the simplest element, hydrogen. The
common variety of hydrogen has a single proton in
the nucleus and a single electron in an orbital
surrounding the nucleus.
Isotopes of Hydrogen

The common variety of
hydrogen has a single
proton in the nucleus
and a single electron in
an orbital surrounding
the nucleus.
Isotopes of Hydrogen
Deuterium

There is another variety of
hydrogen that has a neutron in
the nucleus as well as the proton.
It still has only 1 proton so it
remains the element hydrogen
but now it weighs twice as
much. This is an example of an
isotope and this isotope of
hydrogen is called deuterium.
When it is combined with
oxygen in the compound water;
that water is called heavy water
because indeed it is heavier than
ordinary water. We call
deuterium a stable isotope
Isotopes of Hydrogen
Tritium

There is still another
isotope of hydrogen,
called tritium, that has
1 proton and 2 neutrons
in the nucleus.
Drawing Models of Isotopes
8
Carbon-12
Carbon-14
Naming Isotopes
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Carbon-12
Carbon-14
Uranium-238
Uranium - 235
Oxygen – 14
Oxygen - 16
The number following the element
name is its mass number. We
identify different isotopes by their
mass number since that is what
makes them isotopes in the first
place. They just have a different
number of neutrons in the
nucleus. The number of
PROTONS Always remains the
same.
Ions
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Ions are charged particles
When an atom loses or gains an electron the
atom becomes a charged particle
Group 1A readily give away their valence
electron, when they do they form positive ions
EXAMPLE: Lithium gives away its electron
it forms Li+ (a positive 1 ion)
Drawing Bohr Models Wrap-up
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Purpose:
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To show all subatomic
particles
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Protons
Neutrons
Electrons
To show atomic #
To show mass #
To show idea of a neutral
atom
To show the idea of an ion
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Energy Levels
The Periodic Table
Organization and Characteriestics
Periodic Table History
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Mendeleev gets credit for the arrangement of
the modern periodic table
See Section 5.1 p126 -129
The modern periodic table is arranged by
increasing atomic number (number of
protons)
The Periodic Table
Classes of Elements
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Metals
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Non-metals
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Solids at room temp. (except mercury)
Good extremely reactive
Groups 3b -12b are Transition Metals
See chart: p. 132
Poor conductors of heat and electric current
Low boiling points, most gases at room temp
Nonmetals that are solids at room temp. tend to be brittle
Metalloids
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Their properties fall between metals and nonmetals
Metalloids ability to conduct electric current varies with temp.
Metals

Metals tend to lose
electrons to form
positive ions rather
than to gain electrons
and become negative
ions
Metals - Continued
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Metals makeup more than 75% of the elements in
the periodic table. Metals are characterized by the
following physical properties.
1. They have metallic shine or luster.
2. They are usually solids at room temperature.
3. They are malleable. Malleable means that metals
can be hammered, pounded, or pressed into different
shapes without breaking.
4. They are ductile meaning that they can be drawn
into thin sheets or wires without breaking. 5. They
are good conductors of heat and electricity.
Metals vs. Non-metals
Non-Metals
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There are 17 nonmetals in
the periodic table, and they
are characterized by four
major physical properties.
1. They rarely have
metallic luster.
2. They are usually gases at
room temperature.
3. Nonmetallic solids are
neither malleable nor
ductile.
4. They are poor
conductors of heat and
electricity
NonMetals shown in BLUE
Metalloids
Metalloids are in PURPLE
Periods
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All of the elements in a
period have the same
number of atomic
orbitals
There are 7 rows or
periods
Atomic number
increases across rows
Groups
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When a column goes from top to
bottom, it's called a group. The
elements in a group have the
same number of electrons in
their outer orbital.
Members of groups have have
similar electron configurations
Electron configuration
determines its chemical
properties
There are 32 columns or groups
Special Arrangements

Hydrogen and helium
are special elements.
Hydrogen can have the
talents and electrons of
two groups, one and
seven.
Families: Groups or Columns
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EXAMPLES OF FAMILIES
- Alkali Metals
- Alkaline Earth Metals
- Transition Metals
- Halogen Gases
- Inert Gases (Noble Gases)
EXAMPLES OF PHYSICAL PROPERTIES
- Density
- Boiling Point
- Melting Point
- Conductivity
- Heat Capacity

EXAMPLES OF CHEMICAL PROPERTIES
- Valence electrons
- Reactivity
- Radioactivity
Group 1A: Alkali Metals
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Hydrogen is a very special
element of the periodic
table and doesn't belong to
any family. While
hydrogen sits in Group I, it
is NOT an alkali metal.
Alkali Metals are found in
nature only as compounds.
They are highly reactive!!!
Least
More
reative
Reactive
Group 2A: Alkaline Earth Metals

The members of the
alkaline earth metals
include: beryllium
(Be), magnesium (Mg),
calcium (Ca), strontium
(Sr), barium (Ba) and
radium (Ra).
Alkaline Earth Metals

While not as reactive as the alkali metals, this
family knows how to make bonds very easily.
Each of them has two electrons in their outer
shells. They are ready to give up those two
electrons in electrovalent bonds. Sometimes
you will see them with two halogen atoms
(BeF2) and sometimes they might form a
double bond (CaO).
Alkaline Earth Metals, cont.

The other elements are found in many items
including fireworks, batteries, flashbulbs, and
special alloys. The lighter alkaline earth
metals such as magnesium and calcium are
very important in animal and plant
physiology. You all know that calcium helps
build your bones
Group 3A: Boron Family
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Boron is a Metalloid and is hard and brittle
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Boron occurs with oxygen, never found in nature
by itself
It is important in making heat resistant glass
Aluminum, Gallium, Indium, and Thallium
are all metals
Group 4A: The Carbon Family
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Carbon, Silicon, Germanium, Tin, & Lead
Carbon the basis for organic compounds
Silicon is the 2nd most abundant element
found in the Earth’s crust. It is used in glass
making, computer chips, and solar cells
Group 5A: Nitrogen Family
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Contains 2 nonmetals: Nitrogen &
Phosphorus (often used in fertilizers)
Contains 2 metalloids: arsenic & antimony
Contains 1 metal: bismuth
Group 6A: Oxygen Family
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3 nonmetals: oxygen, sulfur, & selenium
2 metalloids: tellurium & polonium
Have 6 valence electrons
Group 7A: Halogens
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The elements included are
Fluorine (F), Chlorine (Cl),
Bromine (Br), Iodine (I),
and Astatine (At).
When a halogen combines
with another element, the
resulting compound is
called a halide. One of the
best examples of a halide is
sodium chloride (NaCl)
Halogens
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Have 7 valence electrons
Readily bonds with group 1A
Highly reactive non-metals, fluorine is the
most reactive
Properties of Halogens
Group 8A: Noble Gases (Inert)
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Group 8A
Usually colorless,
odorless, and
nonreactive
Transition Metals

Transition metals are
good examples of
advanced shell ideas.
They have a lot of
electrons and distribute
them in different ways.
Transition Metals Rules

Transition metals are able to put more than
eight electrons in the shell that is one in from
the outermost shell. Think about argon (Ar). It
has 18 electrons set up in a 2-8-8 order.
Scandium is only 3 spots away with 21
electrons, but it has a configuration of 2-8-92. Wow! This is where it starts. This is the
point in the periodic table where you can
place more than 8 electrons in a shell
Ionization Energy
Ground State
When all of the electrons in an atom have the
lowest possible energy it is in ground state.
This is the most stable for that element
Name that Element
Name That Element