Transcript chemical bonds

Ch. 6 Chemical Bonding
What type of atom is stable or
neutral in nature?
Noble Gases – outer energy level
is satisfied
What is a chemical bond?
An attraction between two atoms
that combine to become more
stable.
2 Types of Chemical Bonds
1. Ionic Bond – a forced attraction
between positive and negative ions.
The atom either gains or loses
electrons.
Ex. Na + Cl
2. Covalent Bond – a bond that results
in sharing electrons. Electrons are
shared between atoms.
Ex. Cl2
Polar vs. Nonpolar Molecules
Polar Molecules – atoms with opposite
charges that combine.
Ex. Ionic bonds & some covalent
bonds
Nonpolar Molecules – atoms with
alike charges that combine.
Ex. Covalent bonds
What is the smallest unit quantity of matter
which can exist by itself and retain all the
properties of the original substance.
Molecule
There are at least 2 atoms for each molecule.
A molecule that contains 2 atoms of the same
element is called?
Diatomic Molecule
Molecular Formula shows the types and
numbers of atoms combined in a single
molecule.
C, H, and O make up over 90% of all the known
compounds.
` energy is the energy needed to break a
Bond
chemical bond and form neutral atoms.
Ex. Pg. 168
The bond energy is higher as the bond length
becomes shorter.
Octet Rule – states that chemical compounds tend
to form so that each atom, by gaining, losing, or
sharing electrons, has an octet of electrons in its
highest occupied energy level. (Use Dot Diagram)
Lewis Dot Structures are formulas with
atomic symbols and inner-shell electrons,
dot-pairs or dashes between 2 atomic
symbols represent electron pairs.
Examples???
Structural Formula – indicates the type of
bond between atoms.
Examples???
Single bond – sharing of 1 pair of
electrons between 2 atoms.
Double bond – sharing of 2 pair of
electrons between atoms.
Triple bond – sharing of 3 pair of
electrons between atoms.
Sample Problems  6-2, 6-3, 6-4
Polyatomic Ion – is a charged group of
atoms.
Ex. OH-, NH4+
Ionic Compound – is composed of
positive & negative ions combined so
that positive and negative charges are
equal.
Ex. Na + Cl  NaCl
Ionic compounds are usually crystal
structure
Formula Unit – a collection of atoms
from which a compound’s formula can
be established.
Ex. Ca2+ + F-  CaF2
Metallic Bonding
Metallic bonds are chemical bonds
resulting from the attraction between
positive ions & surrounding mobile
electrons.
Bonds between metals
Electrons flow easier  metals are
more rigid.
Malleability – ability to roll metals into
sheets.
Ductility – ability to draw metals into wire
VSEPR Theory
VSEPR theory states the electrostatic
repulsion between the valence-shell
electron pairs surrounding an atom
causes these pairs to be oriented as
far apart as possible.
Pg. 186  Table 6-5
Sample Problems 6-5, 6-6