CHEMISTRY
CHAPTER 6
Ionic and Metallic Bonding
Covalent Bonding
CHEMICAL BONDS
• A Chemical bond is a force that holds two or more atoms together.
• Chemical bonds involve (use) the valence electrons in the atoms.
BONDS, CHEMICAL BONDS
ELEMENTS IN A GROUP
• Behave similarly b/c they contain the same
number of valence electrons
• Valence electrons are electrons in the highest
occupied energy level
• Valence electrons determine an atom’s
chemical properties
VALENCE ELECTRONS
• Valence electrons of a representative element = group
number
• Group 1A = 1 valence electron
• Group 4A (carbon) = 4 valence e- Group 5A (nitrogen) = 5
valence e• Group 6A (oxygen) = 6 valence e• Noble gases (group 8A) = 8 valence
• EXCEPT FOR HELIUM = 2 valence e-
ELECTRONS IN CHEMICAL BONDS
• Are the valence
electrons
• Electron dot structures
are diagrams that
show the valence
electrons as dots
around the symbol
LEWIS STRUCTURES
1) Find your element on the periodic table.
2) Determine the number of valence electrons.
3) This is how many electrons you will draw.
LEWIS STRUCTURES
• Find out which group
(column) your element is in.
• This will tell you the number
of valence electrons your
element has.
• You will only draw the
valence electrons.
GROUPS REVIEW
Group 1 = 1 electron
Group 2 = 2 electrons
Group 8 = 8 electrons
Except for He, it
has 2 electrons
•Each column is
called a “group”
•Each element in a
group has the same
number of electrons
in their outer orbital,
also known as
“shells”.
•The electrons in
the outer shell are
called “valence
electrons”
1)
LEWIS
STRUCTURES
Write the element
symbol.
2) Carbon is in the 4th
group, so it has 4
valence electrons.
3) Starting at the right,
draw 4 electrons, or
dots, counter-clockwise
around the element
symbol.
LEWIS STRUCTURES
1) Check your work.
2) Using your periodic
table, check that
Carbon is in the 4th
group.
3) You should have 4 total
electrons, or dots, drawn
in for Carbon.
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
LEWIS STRUCTURES
On your worksheet, try these
elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
NOBLE GASES
• Unreactive in chemical reactions
• Octet rule: in forming compounds, atoms tend
to achieve the electron configurations of a
noble gas
• Metallic elements tend to LOSE valence electrons
• Leave a complete octet in the next lowest energy
level
• Nonmetallic elements tend to gain or SHARE
electrons with another nonmetallic element to
achieve a complete octet
• Atoms are electrically neutral b/c the # of protons =
# of electrons
• An ion forms as an atom or group of atoms loses or
gains electrons
• A cation is a positive ion formed by the LOSS of
valence electrons
• Name a cation the same as the atom (just add
“ion”)
CATIONS
• Differ chemically from
their atoms
• Na atom explosive with
water
• Na+ ion in NaCl
unreactive and harmless
• K atom explosive with
water
• K+ ion in bananas
harmless
CATIONS
• Loses one valence electron to become a
positively charged sodium ion (Na+ )
• Now, sodium has an electron configuration like
neon
• Magnesium has 2 valence electrons
• LOSES 2 electrons to have a +2
FORMATION OF POSITIVE IONS
• Lose one or more electrons
TRANSITION METALS
• ALWAYS LOSE ELECTRONS TO FORM CATIONS
• Number of electrons lost can vary
• Ex: Iron (Fe) can lose 2 or 3 e• Fe+2 or Fe+3
• Transition metals can sometimes form pseudo-noble gas
configurations
• Silver (Ag) would have to lose 11 or gain 7 electrons. Instead, loses
it’s one 5s
• Then has 18e in outer most energy level
ANIONS
• An atom or group of atoms with a negative
charge. Atom must GAIN electrons to
become negative.
• The name of the anion usually ends in “-ide”
• Chlorine (Cl)  Chloride (Cl-)
• Oxygen (O)  Oxide (O-2)
ANIONS
• Easier for nonmetals to gain electrons vs. losing them
b/c they have relatively full valence shells
• Halide ions: ions produced when halogens (like
chlorine, fluorine) gain one electron
• All halide ions have a charge of -1
• Oxygen forms ions by gaining 2 electrons (O-2)
FORMATION OF NEGATIVE IONS