FORMING IONS

Why do
ions form?
All elements want to be like
their closest noble gas and have
8 electrons in their last energy
level
Some elements have to lose
electrons while others gain
electrons to get this ”stable
state”

Positively
Charged Ions
(Cations)
•When an atom loses an
electron, you get a
POSITIVELY charged ion.
•Cations are usually
metals (less than 4
electrons in their outer
shell)
•Examples; Na+, Mg2+,
Al3+

Negatively
Charged Ions
(Anions)
• When an atom gains
an electron, you get
a NEGATIVELY
charged ion.
• Anions are usually
non-metals (4 or
more than 4
electrons in their
outer shell)
• Examples: O2-, F-, N3-

•Determine the charge of
the following:
1. Mg
2. P
• F
• K
• Cs
• S
• I
• Al
• Ba
• Br
1

NAMING IONS
•Positive ions are
Cations.
•Use the name of
the element plus
the word ion.
•Ca2+ - Calcium
ion
•Na+ - Sodium ion
Negative ions are
Anions.
Use the name of the
element, drop ending
and add – “ide”
S-2 – Sulfide ion
Cl- - Chloride ion

Formula
Writing
Divide If there is common multiple, divide each subscript by
the multiple to simplify.
Use Use the cross-over method to create the chemical
formula.
Write Write them on top right of each substance ( the
metal should always be written first)
Determine Determine the charge of the metal and the non-
metal.

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