Chapter 6 Section 1 Notes
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Electron Configuration
A. Stable Electron Configuration
a. When the highest occupied energy level of an atom is
filled with electrons, the atom is stable and not likely
to react.
b. The noble gases have stable electron configurations
with eight valence electrons.
c. The chemical properties of an element depend on the
number of valence electrons.
Electron Configuration
d. A model of an atom that focuses on only the valence
electrons is the electron dot diagram.
e. An electron dot diagram is a model of an atom in which
each dot represents a valence electron. The symbol in
the center represents the nucleus.
f. Orbital diagrams and Electron Configurations both
show how the electrons fill the various orbitals in each
energy level. (Refer to the Electron Configuration
activity)
Electron Dot Diagram
1A
2A
3A
4A
5A
6A
7A
H
8A
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Ga
Ge
As
Se
Br
Kr
Ionic Bonding
B. Ionic Bonding
a. Elements that do not have a complete set of valence electrons
tend to react.
b. The goal of an element reacting is to achieve an electron
configuration similar to that of a noble gas.
c. Some elements achieve stable electron configurations
through the transfer of electrons between atoms.
Ex. 1) What happens to the electrons when sodium reacts with
chlorine?
 An electron is transferred from each sodium atom to a chlorine
atom. Each atom ends up with a more stable electron
arrangement than it had before.
Ionic Bonding
d. When an atom gains or loses an electron, the number of
protons is no longer equal to the number of electrons.
Therefore the charge of the atom is no longer neutral.
e. An ion is an atom that has a net positive or negative
electric charge. It is represented by a + or – sign. (Refer
to example 1)
f. An anion is an ion with a negative charge.
Ionic Bonding
g. A cation is an ion with a positive charge.
h. A chemical bond is the force that holds atoms or ions
together.
i. An ionic bond is the force that holds cations and anions
together.
1. An ionic bond forms when electrons are transferred
from one atom to another.
Ionization Energy
C. Ionization Energy
a. The amount of energy used to remove an electron from
an atom.
b. The lower the ionization energy, the easier it is to
remove an electron from an atom.
c. This energy decreases going down the periodic table
and increases going across the periodic table from left to
right.
Ionic Compounds
D. Ionic Compounds
a. Compounds that contain ionic bonds.
b. A chemical formula is a notation that shows what
elements a compound contains and the ratio of atoms or
ions of these elements in the compound.
Ex. 1) Sodium Chloride
Ex. 2) Magnesium Chloride