Objectives
Be able to explain why atoms sometimes
join to form bonds
 Be able to explain why some atoms transfer
their valence electrons to form ionic bonds
and others share valence electrons to form
covalent bonds
 Be able to differentiate between ionic,
covalent, and metallic bonds
 Compare the properties of substances with
different types of bonds

Important Vocabulary
 Stable
electron configuration
 Ionic bond
 Metallic bond
 Covalent bond
 Polar covalent bond
 Dipole
 Non-polar covalent bond
 Polyatomic ions
What Holds Bonded Atoms
Together?
1. A stable electron configuration
2. Bonds can bend without breaking
3. Bonds can stretch without breaking
Stable Electron Configuration


Happens when atoms
have full outermost s &
p orbitals
Bonded atoms also have
electron configuration
structures similar to
noble gases
Bonds can Bend & Stretch


Bonds are not
completely rigid
Many act like flexible
springs in which the
distance of the nuclei
of the atoms changes
Types of Bonds
 Ionic
 Metallic
 Covalent
 Polar
 Non polar
 Polyatomic Ions
Ionic Bonds
Are formed between oppositely charged
ions
 They are formed by the transfer of
electrons, one atom loses electrons and the
other gains electrons
 i.e. Na+ + Cl- = NaCl
 Ionic compounds are in the form of ion
networks NOT molecules
 Ionic compounds when melted or dissolved in
water can conduct electricity

Ionic Bonds
Metallic Bonds



Is a bond formed by the attraction
between positively charged metal ions & the
electrons around them
Electrons move freely between metal atoms
Attractive forces between nuclei and
neighboring atom’s electrons pack the atoms
close together, overlapping the energy levels
Metallic Bonds
Covalent Bonds
 Compounds
made of molecules have
covalent bonds
 Often formed between nonmetals
 Can be solids, liquids, or gases
 Share electrons
 Can share more than 1 electron
 2 main types:
 Polar covalent bonds
 Non polar covalent bonds
Polar Covalent Bonds


Are when 2 different atoms share electrons,
but the sharing is not equal
This creates a dipole, a set of partial charges
Non Polar Covalent Bonds


Occur when electrons are shared equally
It can happen between atoms of the same
element or atoms of two different elements
Double & Triple Covalent Bonds
Polyatomic Ions
Are made of groups of
covalently bonded atoms
that have lost or gained
electrons
 In other words, they have
both ionic and covalent
bonds
 We use parentheses to group
the atoms of a polyatomic ion
 (NH4)2SO4
 The charge of a polyatomic
ion applies to the entire ion
