Concept: Types of Chemical Bonds
What is chemical bonding?
 Occurs when there is a strong attraction between the
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valence electrons of one atom and the nucleus of
another atom
Formed by rearranging electrons
Atoms have relatively high potential energy as
independent particles; but, tend to move toward low
potential energy
The way electrons are distributed will determine the
type of bond
Most chemical bonds are partly ionic and partly
covalent
What is chemical bonding?
3 types of Chemical Bonding
1. Ionic
2. Covalent
3. Metallic
Ionic and covalent are the two main types of bonding!!!!
LEQ: What are characteristics of ionic
bonding?
 Between metal and nonmetal
 Electrical attraction (opposite charges hold
compounds together).
 Smallest particle is an ion
 Solid at room temperature; but, brittle
 Crystalline lattice structure (repeating patterns of
ions)
LEQ: What are characteristics of ionic
bonding?
 Stronger than covalent bonds
 Formula unit
 Makes atoms more stable
 Lowers potential energy
 High melting and boiling points
 Good conductors of electricity (in molten state)
LEQ: What are characteristics of ionic
bonding?
 Ionic bonds (giving or taking of electrons)
 Cations
 + charge
 Lose/give up electrons
 metals
 Anions
 (-) charge
 Gain electrons
 nonmetals
LEQ: What are characteristics of
ionic bonding?
 Terms to know
 Ionic compound
 Compound composed of +/- ions that combine so that
they are equal
 Formula Unit
 Simplest ratio of (+) ions to (–) ions represented by the
formula
LEQ: What are characteristics of
covalent bonding?
 2 nonmetals share electrons so that both have 8
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valence electrons (except H)
Forms molecules
Liquid or gas at room temperature
Illustrated with Lewis Dot
Can be polar or non-polar
Not as strong as/weaker than ionic bonds
Makes atoms more stable by lowering potential energy
Low melting and boiling points
LEQ: What are characteristics of
covalent bonding?
Non-polar covalent
Electrons shared equally
No charge created
Occurs between 2 identical atoms
7 diatomic molecules
(HOClBrFIN)
LEQ: What are characteristics of
covalent bonding?
 Polar Covalent
 Electrons not shared equally (tug-of-war)
 Electrons spend more time around the more
electronegative atom
 Slight charges created
 (-) charge around the more electronegative atom.
 Example: water, HCl (hydrochloric acid)
LEQ: What are characteristics of
covalent bonding?
 Terms to Know
 Molecule
 A neutral group of atoms held together by a covalent
bond
 Molecular compound
 Another name for covalent compound
 Chemical formula
 # of atoms of each element in a compound represented
by using symbols and subscripts
LEQ: What are characteristics of
covalent bonding?
 Terms to Know
 Molecular Formula
 Types and numbers of atoms in a single molecule
 Used for covalent compounds
 Example: H2O
LEQ: What are characteristics of
covalent bonding?
1. To lower potential energy by making the substance
more stable
 Attract/repel each other until the distance between the
atoms is reached where the repulsion between the like
charges equal the attraction of the opposite charges
 Atoms have relatively high potential energy as
independent particles; but, tend to move toward low
potential energy
LEQ: What are characteristics of
covalent bonding?
2. To form octet
 Octet rule – atoms tend to form compounds (by gaining,
losing, or sharing electrons) so that the highest energy
level is full (8 electrons in s & p orbitals)
 How many more electrons does nitrogen need to satisfy
the octet rule if its electron configuration is 1s22s22p3 ?
LEQ: What are characteristics of
covalent bonding?
 Exceptions to octet rule:
 Hydrogen – surrounded up to 2 electrons
 Boron – up to 6 electrons
 Fluorine, oxygen, and chlorine – more than 8 electrons
because they have high electronegativities
LEQ: What are characteristics of
ionic and covalent bonding?
 Differences in Electronegativity
 0-0.3 (0%-5%)Non-polar covalent
 Diatomic molecules
 0.3-1.7 (5%-50%)polar-covalent
 HCl
 1.7-3.3 (50% - 100%)ionic
 NaCl
Lewis Dot Structures
 Uses electron dot to illustrate what a molecule looks
like
 Electron dot notation
 Only shows valence electrons
 Symbol of element stands for nucleus and all inner shell
electrons
 Lewis Dot can show single, double, and triple bonds
 If carbon is present, use as central atom. If not, use the
least electronegative atom as the central atom. NEVER
use hydrogen as central atom.
Lewis Dot Structures
 Examples:
 IBr
 O2
 CH3Br
 OF2
 HCL
 CF4
What are unique characteristics of
Polyatomic Ions?
 Polyatomic Ions
 A group of covalently bonded atoms that have a charge
representing extra electrons
 PO43- , NH4+
 Negative – excess of electrons
 Positive – shortage of electrons
 Has molecular and ionic characteristics
Metallic Bonding
 Chemical bonding that results from an attractions
between metal atoms and the surrounding electrons
 The ions are capable of sliding past one another
 Creates the characteristics of being malleable, ductile,
and shiny.