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 IONSin 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(8 valence electrons).

In covalent bonding,atoms still want to achievea noble gas configuration.

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

F2

Fluorineforms

acovalent

bondwithitself

FFHowwilltwofluorineatomsreact?

FFEach fluorine atom wants to gain one electron to have 8 valence electrons.

FFNeither atom will give up an electron

What’s the solution – what can theydo to achieve 8 valence electrons?

FF

F F

F F

F F

F F8 valence electrons

F F

circle the electrons foreach atom that completestheir octets

8 valence electrons

F F

circle the electrons foreach atom that completestheir octets

By sharing the electron pair in the middle, each fluorine atom feels like it has 8 valence electrons

F F

circle the electrons foreach atom that completestheir octets

The electron pair in the middle(the circled one) is shared by the two atoms of fluorine.

F F

circle the electrons foreach atom that completestheir octets

This is called the bonding pair

F F

circle the electrons foreach atom that completestheir octets

It is a single bonding pair

F F

circle the electrons foreach atom that completestheir octets

It is called a SINGLE BOND

F F

circle the electrons foreach atom that completestheir octets

Single bonds are shown with with a dash

F F

circle the electrons foreach atom that completestheir octets

This is the fluorine molecule,

F2

O2How will this molecule form?

OO

OOEach atom has two unpaired electrons

OO

OO

OO

OO

OO

OO

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= 8 valence electrons

OO

6 valence electronsplus 2 shared electrons= 8 valence electrons

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,

O2

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. Formula3. Graphical representation

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