Covalent Bonding Occurs when atoms share

electrons Different from ionic bonding

Ionic Bond = Atoms completely transfer electrons

Covalent bonding occurs when two (or more) atoms share one or more electrons

Covalent Bonding Covalent bonding occurs when

two or more atoms bond together

The atoms on the right side of the periodic table like to gain electrons These elements will share electrons

in order to fill their valence shells

Covalent Bonding Atoms become chemically stable

and neutral by sharing electrons (not losing or gaining)

Covalent Bonding Covalent bonding is best

illustrated using Dot Diagrams Atomic symbol with the valence

electrons shown You’ve done these before!

Covalent Bonding of Two Hydrogen Atoms

H is in Group One = One valence electron in its outer/only/valence shell

The most electrons in this shell is two electrons

Each H atom will 'want' to pick up a second electron

Covalent Bonding of Two Hydrogen Atoms In order to pick up a second

electron, hydrogen atoms will react with nearby H atoms to form the molecule H2

Covalent Bonding of Two Hydrogen Atoms The H2 is a combination of

equally matched atoms The atoms will share each others

single electron Both atoms have a full valence shell

Covalent Bonding of Two Hydrogen Atoms

The two hydrogen atoms “share” their electrons

Both have “two” valence electrons, so are “happy”

H H

Covalent Bonding Examples Covalent Bonding Chlorine

Covalent Bonding Examples Water (H2O)

is a covalently bonded molecule

Covalent Bonding Examples Covalent Molecule Examples

WATER (H2O) CARBON DIOXIDE (CO2) OXYGEN (O2) METHANE (CH4)

Molecular Compounds There are seven elements that will

form a covalent bond with the same type of atom. H2 F2 Cl2 Br2 I2 N2 O2

Covalent Bonding Multiple Bonds:

Every pair of electrons shared between two atoms is a single covalent bond

Some atoms can share multiple pairs of electrons, forming multiple covalent bonds 

For example, oxygen (which has six valence electrons) needs two electrons to complete its valence shell

When two oxygen atoms form the molecule O2, they share two pairs of electrons, forming two covalent bonds

Polarity Non-Polar Covalent Bonds

Bonds where the bonding electrons are shared equally between atoms

No charge

Polarity Polar Covalent Bonds

One atom attracts the electrons more than another resulting in uneven sharing

Slight charge

Steps for covalent bonding problems 1. Write the symbol for each element

in the molecule. 2. Create dot diagrams for each

(helps to use different colors for each element)

3. Rearrange electrons to pair up electrons from each atom.

4. Draw circles to show sharing of electrons

5. Write the chemical formula for the molecule

Molecules vs Compounds

Term Molecule Compound

Definition More than one atom bonded together with covalent bonds.

Atoms of more than one type of element are bonded together (either ionic or covalent bonds)

Examples H20, CH4, CO2, O2 H20, CH4, CO2, NaCl