Chapter 7
Objectives-7.1

Determine the number of valence
electrons in a representative element.

Explain how the octet rule applies to
atoms of metallic and nonmetallic
elements.

Describe how cations form.

Explain how anions form.
Review
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Describe what a valence electron is, and its location
around the atom.
Determine the valence electrons for Oxygen (AN=8),
Cesium (AN=55), Neon (AN=10), and Bromine
(AN=35)
State the charge of the following elements when they
become ions: Lithium (Li), Beryllium (Be), Boron (B),
Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F),
Neon (Ne).
How many valence electrons do the Noble Gases
hold. (Excluding Helium)
What are the names of the elements found in
groups: IA, IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA? (1-8)
Prior Knowledge
We will be using much of the material
we learned in chapter 6 for this unit.
 Valence electrons
 Ions
 Locations on the Periodic Table

Valence Electrons
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Recalling from Chapter 6, Valence
Electrons, are the electrons in the
highest occupied energy level of an
element’s atoms.
There are two basic methods to
discover the number of valence
electrons an atom holds.
 First, we can produce an electron
configuration
 Second we can look at the group that
element is held in.
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The elements that are not valence,
the blue electrons in the picture to
the side, are called core electrons,
electrons in all energy levels below
the highest.
KEYWORDS- CORE ELECTRONS
Valence Electrons and Bonding
When atoms form compounds, a bond is
formed between the electrons.
 It is easier to form a bond with atoms
that openings on their valence level.
 To help represent this we draw dots
around the elements.
 This is called a Lewis
Dot Structure, or an
Electron Dot Structure.

Your Turn
Try and draw the Electron dot structures
for the following elements.
 Lithium (Li), Beryllium (Be), Boron (B),
Carbon (C), Nitrogen (N), Oxygen (O),
Fluorine (F).

The Octet Rule
We learned previously that noble gases
are the most stable.
 Knowing that the noble gases are the
most stable, because they contain a set
number of valence electrons, all other
elements strive to be like them.

The Octet Rule
By having the most stable elements all
having equal numbers of valence
electrons we discover a key concept.
 The octet rule, where when compounds
are formed, atoms tend to achieve the
electron configuration of noble gases.
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KEYWORD- OCTET RULE
The Octet Rule

Atoms of metals tend to lose their
valence electrons, leaving a complete
octet.

Atoms in some non-metals tend to gain
electrons, or share, with another nonmetal to achieve a complete octet.
Formation of Cations and Anions
As we have learned in the past Cations
and Anions.
 Cations LOSE a negatively charged
electron, and thus become positively
charged.

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Anions GAIN a negatively charged
electron, and thus become negatively
charged.
Formation of Transition Metal Ions
The elements in the transition section of
the periodic table, and some outside of
it, have unique representations of ions.
 When a metal forms an ion we write is
as follows: Fe3+, or Iron (III).
 When dealing with metals, roman
numerals is equivalent to charge.
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Closing
How do Cations Form?
 How do Anions Form?
 Non-metals tend to gain or lose
electrons?
 Metals tend to gain or lose electrons?
 The octet rule states that a stable atom
will have how many valence electrons?
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