Bonding

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Bonding
By Mary Agarwala
Chemical Bonds?
 What are they?
 Why do atoms form them?
 Why are some stronger than
others?
Ionic Bonding
 + charged ion is attracted to a – charged
ion
 A nonmetal + a metal = ionic bond
 Ionic compound is entirely made up of ions
 Positively charged ion (Cation)
 Negatively charged ion (Anion)
 Ex. NaCl
Ionic properties
 High melting points which
means it ionic bonds are strong
bond
 Brittle
 Dissolves in water, a process
that breaks the ionic bonds
and separates the ions (makes
solutions that conduct
electricity)
 Polar…”Likes dissolves likes”
 Liquid (motlen) ionic
compounds conduct electricity
 Solid ionic compounds do not
conduct electricity well
OCTET RULE
Atoms tend to gain,
lose, or share
electrons in order to
acquire a full set of
valence electrons
Lewis Dot
Diagrams
Valence electrons are
represented as dots placed
around the element symbol
KNOW HOW TO WRITE IONIC
COMPOUNDS
Empirical formula vs.
Molecular formula
Empirical Formula
 Denote the ratio of ions in a
compound
 Chemical formula
Molecular Formula
 Molecular compound
 Describes the composition
of a molecular compound
 The lowest possible whole
 Tells how many atoms are in
 The compound wants to be
 Ex. Glucose (C6H12O6)
number subscripts for the
elements
electrically neutral
a single molecule of the
compound
Covalent Bonds
-A covalent bond is formed
by a shared pair of electrons
between two atoms
-Each atom wants to be
“octet happy”
-Nonmetal + nonmetal =
Covalent bond
-This is best shown by
combining atoms’ Lewis
structures
Multiple Bonds
Double Bonds
Triple Bonds
 (show picture)
 (show picture)
 (text book pg 239. Eq.4)
 (text book pg. 239 Eq.5)
Exceptions to the Octet
Rule
 Atoms with less than an octet (BF3)
 Atoms with more than an octet (SF4)
 Molecules with an odd number of electrons
(NO)
 Don’t sweat the exceptions for the regents
Electronegativity
 Property of an element that indicates how
strongly an atom of that element attracts
electrons in a chemical bond
 When one atom is SIGNIFICANTLY MORE EN
than another, the covalent bond is POLAR.
 2 atoms, in a bond, with SIMILAR ENs are
NONPOLAR
 KNOW EN TRENDS!!! Remember F is the
biggest (EN=4.0)
Bond Type by
Electronegativity
Electronegativity
Difference
Less than or
equal to 0.4
Between 0.4 and
2.0
Greater than or
equal to 2.0
Bond Type
Nonpolar
covalent
Polar covalent
ionic
Naming Chemical
Compounds
Chemists name a compound according to the
atoms and bonds that compose it
 Write cation first
Naming Ionic
Compounds
 No need to specify
number of atoms
(AKA no prefixes)
Ex. KI (potassium
iodide)
Ex. KNO3 (potassium
nitrate)
Ex. CuSO4 (copper(1)
oxide)
Naming
Molecular
Compounds
 Know numerical
prefixes
 Suffix –ide is added to
the atom with a
greater EN
 Ex. NO2 (nitrogen
dioxide)
 Ex. BF3 (boron
trifluoride)
 Ex. P2O5
(diphosphorus
pentoxide)
THE END
“Good Luck.. Do Well!!!!”

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