Covalent bonding

Grade 9 Chemistry

Starter

• What ions do Chlorine form?

• Imagine you have 2 chlorine ions – how could they help EACH OTHER to reach a stable state?

• It might help if you draw out the Lewis structures for 2 chlorine ions!

LET’SFIRSTREVIEWIONICBONDING

In an IONIC bond,electrons are lost or gained,resulting in the formation of IONS

in ionic compounds.

FK

FK

FK

FK

FK

FK

FK

FK+ _

FK+ _

The compound potassium fluorideconsists of potassium (K+) ions

and fluoride (F-) ions

FK+ _

The ionic bond is the attractionbetween the positive K+ ion

and the negative F- ion

Sowhatarecovalentbonds?

In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).

In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).

But rather than losing or gainingelectrons,atoms now share an electron pair.

In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).

But rather than losing or gainingelectrons,atoms now share an electron pair.

The shared electron pairis called a bonding pair

Cl2

Chlorineforms

acovalent

bondwithitself

ClClHowwilltwochlorineatomsreact?

ClClEach chlorine atom wants to gain one electron to achieve an octet

ClClNeither atom will give up an electron –chlorine is highly electronegative.

What’s the solution – what can theydo to achieve an octet?

ClCl

Cl Cl

Cl Cl

Cl Cl

Cl Cloctet

Cl Cl

circle the electrons foreach atom that completestheir octets

octet

Cl Cl

circle the electrons foreach atom that completestheir octets

The octet is achieved byeach atom sharing theelectron pair in the middle

Cl Cl

circle the electrons foreach atom that completestheir octets

The octet is achieved byeach atom sharing theelectron pair in the middle

Cl Cl

circle the electrons foreach atom that completestheir octets

This is the bonding pair

Cl Cl

circle the electrons foreach atom that completestheir octets

It is a single bonding pair

Cl Cl

circle the electrons foreach atom that completestheir octets

It is called a SINGLE BOND

Cl Cl

circle the electrons foreach atom that completestheir octets

Single bonds are abbreviatedwith a dash

Cl Cl

circle the electrons foreach atom that completestheir octets

This is the chlorine molecule,

Cl2

O2Oxygen is also one of the diatomic molecules

How will two oxygen atoms bond?

OO

OOEach atom has two unpaired electrons

OO

OO

OO

OO

OO

OO

Oxygen atoms are highly electronegative.

So both atoms want to gain two electrons.

OO

Oxygen atoms are highly electronegative.

So both atoms want to gain two electrons.

OO

OO

OO

OO

OO

OOBoth electron pairs are shared.

6 valence electronsplus 2 shared electrons

= full octet

OO

6 valence electronsplus 2 shared electrons

= full octet

OO

two bonding pairs,

OOmaking a double bond

OO =For convenience, the double bond

can be shown as two dashes.

OO

OO =This is the oxygen molecule,

O2this is so

cool!!

COVALENT BONDbond formed by the sharing of electrons

What is a covalent bond?

Atoms ___________ one or more electrons with each other to form the bond.

Each atom is left with a ________________ outer shell.

A covalent bond forms between two _________________.

Example 1: Hydrogen + Hydrogen Example 2: Hydrogen + Oxygen

SHARE

COMPLETE

NONMETALS

1. Dot and cross diagram2. Formula

Covalent Bond

• Between nonmetallic elements of similar electronegativity.

• Formed by sharing electron pairs• They are not conductors at any state• Examples; O2, CO2, C2H6, H2O, SiC

Now try the covalent bonding practice sheet