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Chemical compounds
Formation and nomenclature
Ms. MacInnes
SCI10
Octet rule

All atoms want 8 electrons in their
valence shell, giving them the same
electronic configuration as a noble gas.
This makes it stable, and not reactive.
Ions and compounds

There are three ways an atom can
obtain a “complete” valence shell:



An atom can lose electrons and become
positive (cation)
An atom can gain electrons and become
negative (anion)
Two or more atoms can share electrons

Ions: atom or group of atoms that have an electric
charge (+ or -)

An ion is formed when an atom, or a group of atoms,
lose or gain one or several electrons (e-)

There are 2 types of ions:
1. cation: Positively charged ion, obtained when a
neutral atom loses one or more electrons.
2. anion: Negatively charged ion, obtained when a
neutral atom gains one or more electrons.
There are two types of compounds…

Ionic




Composed of two atoms with
opposite charges (cation and
anion)
Generally, it is a metal
(cation) and a non-metal
(anion)
The atoms form an ionic bond
One atom gives electrons and
the other atom accepts them.



Ex: N
A nonmetal from group 15, it
gains 3 electrons to form the
anion N3- .
N3- = N + 3 eEx: O
A nonmetal from group 16, it
gains 2 e- to become the anion
O2- .
O2- = O + 2 eEx: Na
A metal from group 1, it loses 1
e- to become the cation Na+.
Na+ = Na + 1 e-

Molecular
 Composed of two
atoms which share
electrons
 Generally, they are
made of two or more
non-metals
 The atoms form a
covalent bond
Activity

Open to p. 148-150 in Science Power 10
and complete the activity as written.