Lewis Structures
The chemical symbol for the atom is
surrounded by a number of dots
corresponding to the number of valence
electrons.
Draw Lewis Structures
for the following:
•
•
•
•
•
•
•
Hydrogen
Bromine
Xenon
Calcium
Nitrogen
Sulfur
Aluminum
On one side of the page, draw the
Lewis structure for lithium, sodium
and potassium. On the other side of
the page, draw the Lewis structure
for fluorine, chlorine, and bromine.
What is the easiest way for these
elements to have a full highest
energy level (to achieve stability)?
Ions?
Ion: any atom or group of atoms that carries an
electrical charge. Since protons and neutrons
are fixed in the nucleus, an electron must be
lost or gained to create an ion.
Cation: when a neutral atom (same number of
(p+and e-) gives up an electron, the positively
charged ion that results is called a cation.
Anion: when a neutral atom gains an electron,
the negatively charged ion that results is
called an anion.
Anions are named using the name of the
element but ending in ide and the word ion.
Cl-1 Chloride ion
P-3 Phosphide ion
Cations are named using the name of the
element and the word ion.
Ca+2 Calcium ion
Li+1 Lithium ion
Be
Be
Na
A beryllium atom has 4p+ and 4e-. If we add
energy we can remove the electrons from the
highest energy level. The beryllium atom
then becomes a beryllium ion, which has 4p+
and 2e-. This means the ion has a charge of
+2 +2.
A sodium atom has 11p+ and 11e-. If the
electron in the highest energy level is
removed by energy, a sodium ion remains.
This ion has 11p+ and 10e-, which means it
has a charge of +1.
+1
Na
These ions are both cations.
An oxygen atom has 8p+ and
8e-. When an oxygen atom
gains 2 electrons from another
atom’s highest energy level, it
becomes an oxide ion. This
anion has 8 p+ and 10 e-.
O
-2
O
An energy level can be filled when
an atom gains or loses electrons.
[Na]+1
Na
[Cl]-1
Cl
For example:
Sodium (Na) needs to get rid of
one electron to have a full outer
Becomes a sodium ion energy level, and Chlorine(Cl)
Becomes a chloride ion needs to gain one in order to
have a full outer energy level.
Sodium chloride is formed when sodium
gives an electron to chlorine. Both atoms
become ions. This is called IONIC bonding.
another example:
Mg
O
Magnesium has two valence electrons.
Oxygen has 6 valence electrons.
Magnesium oxide is formed when
magnesium gives two electrons to oxygen.
[Mg]+2 [O]-2
MgO
Magnesium Oxide
What if:
Ca
F
F
Calcium has 2 valence electrons.
Fluorine has 7 valence electrons.
Calcium can provide 1 electron to fluorine.
What does calcium do with its other e-?
[Ca]+2 [F]-1 x 2
CaF2
calcium fluoride
Using Lewis structures how how the
following ionic bonds occur between:
1.
2.
3.
4.
5.
Potassium & bromine
Potassium & oxygen
Potassium & nitrogen
Calcium & chlorine
Beryllium & nitrogen
Draw the Lewis structures and
predict the formula for the following
ionic compounds. Name the ions
formed and draw their symbols.
a) magnesium & fluorine
b) lithium & bromine
c) rhubidium & chlorine
d) calcium & oxygen
e) aluminum & oxygen