Transcript Document
BONDING
REVIEW
Bonds Between Atoms
Polyatomic Ions
Ionic
Covalent
Polar
Nonpolar
Giant
Covalent
Networks
/Crystals
See if you can define the following words before starting the lesson…
• Anion- negative ion
• Cation-positive ion
• Octet Rule- rule that states that atoms tend to gain, lose,
or share electrons so that each atom has full outermost
energy level which is typically 8 electrons.
• Polyatomic Ion- charged group of covalently bound
atoms
• Monatomic Ion- ion formed from a single atom
• Molecule-neutral group of atoms united by covalent
bonds
• Unshared or Lone Pair- pair of electrons that is not
involved in bonding but instead is held exclusively by one
atom.
Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell
electrons
1
2
13
14
15
16
17
H
18
He:
Li Be
B
C
Na Mg
N
O
Al
Si
P
S
: F :Ne :
:Cl :Ar :
Formation of Ions from Metals
Ionic compounds result when metals react with
nonmetals
Metals lose electrons to match the number of valence
electrons of their nearest noble gas
Positive ions form when the number of electrons are
less than the number of protons
•
Group 1 metals
ion 1+
Group 2 metals
ion 2+
Group 13 metals ion 3+
Formation of Sodium Ion
Sodium atom
Na
2-8-1
11 p+
11 e0
– e
Sodium ion
Na +
2-8 ( = Ne)
11 p+
10 e1+
Some Typical Ions with Positive
Charges (Cations)
Group 1
Group 2
Group 13
H+
Mg2+
Al3+
Li+
Ca2+
Na+
Sr2+
K+
Ba2+
Formation of Magnesium Ion
Magnesium atom
Magnesium ion
Mg
2-8-2
12 p+
12 e0
– 2e
Mg2+
2-8 (=Ne)
12 p+
10 e2+
Ions from Nonmetal Ions
In ionic compounds, nonmetals in 15, 16, and 17
gain electrons from metals
Nonmetal add electrons to achieve the octet
arrangement
Nonmetal ionic charge:
3-, 2-, or 1-
Fluoride Ion
unpaired electron
:F
2-7
9 p+
9 e0
+ e
octet
1-
: F:
2-8 (= Ne)
9 p+
10 e1ionic charge
Marriage
Forming
of a bond
is like
marriage
•More stable
•exothermic
Divorce
•Less stable
•Endothermic
The
breaking
of a bond
relates to a
divorce.
Ionic Bonds
•What is an Ionic Bond?
- An Ionic Bond is a chemical bond
resulting from the TRANSFER of electrons
from one bonding atom to another
• When is an ionic bond formed?
- An ionic bond is formed when a cation
(positive ion) transfers electrons to an
anion (negative ion).
What are some characteristics of an ionic
bond?
1. Crystalline at room
temperatures
2. Have higher melting
points and boiling points
compared to covalent
compounds
3. Conduct electrical
current in molten or
solution state but not in
the solid state
4. Polar bonds
Ionic Bond
• Between atoms of metals and nonmetals
with very different electronegativity
• Bond formed by transfer of electrons
• Produce charged ions all states. Conductors
and have high melting point.
• Examples; NaCl, CaCl2, K2O
Ionic Bonds: One Big Greedy Thief Dog!
Covalent Bonds
•What is an Covalent Bond?
- A covalent bond is a chemical bond
resulting from SHARING of electrons
between 2 bonding atoms.
• What forms a covalent bond?
- A covalent bond is formed between two
nonmetals.
What are some characteristics of a covalent
bond?
1.
2.
3.
Covalent bonds have
definite and predicable
shapes.
Very strong
Low melting and boiling
points
1). Ionic bond – electron from Na is transferred to Cl,
this causes a charge imbalance in each atom. The Na
becomes (Na+) and the Cl becomes (Cl-), charged
particles or ions.
Covalent Bond
• Between nonmetallic elements of similar
electronegativity.
• Formed by sharing electron pairs
• Stable non-ionizing particles, they are not
conductors at any state
• Examples; O2, CO2, C2H6, H2O, SiC
Covalent Bonds can have multiple bonds, so you should be
familiar with the following…
Single Covalent Bondchemical bond resulting
from sharing of an electron
pair between two atoms.
Double Covalent Bondchemical bond resulting
from sharing of two electron
pairs between two atoms.
Triple Covalent Bondchemical bond resulting
from sharing of three
electron pairs between two
atoms.
There are three different categories associated with covalent
bonds. What are the 3 different categories?
Covalent
Polar
Nonpolar
Giant
Covalent
Networks
/Crystals
First, we are going to look at Polar Covalent…
What is polar covalent?
-Polar covalent is a description of a
c
bond that has an uneven
distribution
of charge due to an unequal sharing of
bonding electrons.
The boy is not equally
sharing with anyone
else but rather taking
all the food for himself.
Next, we are going to look at Non-Polar Covalent…
What is non-polar covalent?
-Non polar covalent is a covalent
bond that has an even distribution of
charge due to an equal sharing of
bonding electrons.
This couple is
non- polar
because they are
sharing the drink
equally between
them.
Linear
Trigonal Planer
Trigonal Bipyramidal
Tetrahedral
Octahedral
Just as a summary to what each
bond looks like…
NONPOLAR
COVALENT BONDS
when electrons are
shared equally
H2 or Cl2
2. Covalent bonds-
Two atoms share one or more pairs of outer-shell
electrons.
Oxygen Atom
Oxygen Atom
Oxygen Molecule (O2)
POLAR COVALENT
BONDS
when electrons are
shared but shared
unequally
H2O
Polar Covalent Bonds: Unevenly
matched, but willing to share.
- water is a polar molecule because oxygen is more
electronegative than hydrogen, and therefore electrons
are pulled closer to oxygen.