IONIC BONDING

HOW DOES IT WORK?Ionic bonding takes place between metals and non-

metals

Metal atoms try to attain noble gas strucure (full outer shells) by losing electrons to form positive ions

Non-metal atoms try to attain noble gas strucure (full outer shells) by gaining electrons to form negative ions

The positive and negative ions formed attract each other to give an ionic bond.

Sodium Chloride

Sodium has atomic number 11

It therefore has 11 protons in its nucleus

+ + + + + +++ + + +

It also has 11 electrons2 in the inner shell8 in the next shell

1 in the outer shell

SODIUM

Sodium has 11 protons = 11 + charges

Sodium has 11 electrons = 11 - charges

Total = 0. It is a neutral atom

Chlorine has atomic number 17

The number of protons in its nucleus is

+ + + + + +++ + + +

The number of electrons is In the inner shellIn the next shell

In the outer shell

17

1728

7

++ + ++ +

Chlorine has 17 protons = 17 + chargesIt also has 17 electrons = 17 - charges

TOTAL = 0. It is a neutral atom

CHLORINE

Sodium Atom Chorine Atom

Sodium loses one electron to gain noble gas structure (complete outer shell)

Chlorine gains the electron and also gets a complete outer shell of 8 electrons

Now the sodium has11protons (still) = 11+ chargesBut only 10 electrons = 10- charges

Total = +1 which is the charge on the SODIUM ION

+

The chlorine has17protons (still) = 17+ charges

But only 18 electrons = 18- charges

Total = -1 which is the charge on the CHLORIDE ION

-

Both Atoms want complete outer shells of electrons

Sodium Ion Chloride Ion

Magnesium Oxide

MAGNESIUM

Magnesium has atomic Number 12

It therefore has 12 protons in the nucleus

And 12 electrons arranged 2.8.2

12p

OXYGEN

Oxygen has atomic Number 8

It therefore has 8 protons in the nucleus

And 8 electrons arranged 2.6

8p

Magnesium needs to lose 2 electrons to get a complete outer shell

Oxygen needs to gain 2 electrons to get a complete outer shell

Magnesium still has 12 protons = 12+But only 10 electrons = 10 –So overall charge = 2+The ion is written Mg2+

2+

Oxygen still has 8 protons = 8+But now 10 electrons = 10 –So overall charge = 2-The ion is written O2-

2-

Magnesium Fluoride

MAGNESIUM

Magnesium has atomic Number 12

It therefore has 12 protons in the nucleus

And 12 electrons arranged 2.8.2

12p

FLUORINE

Fluorine has atomic Number 9

It therefore has 9 protons in the nucleus

And 8 electrons arranged 2.7

Magnesium needs to lose 2 electrons to get a complete outer shell

But Fluorine needs to gain only 1 electrons to get a complete outer shell

8p

Therefore another fluorine is needed

8p

This gives us the Mg2+ ionAnd two F- ions

The formula is MgF2

IONIC STRUCTURES

POSITIVE ION NEGATIVE ION

Now opposite charges attract!

Positive ions and negative ions form a lattice .

Every positive ion is surrounded by negative ions and every negative ion is surrounded by positive ions.

PROPERTIES OF IONIC COMPOUNDS

Salt Crystals (sodium chloride)

Copper Sulphate crystals

They are crystalline solids

They have high melting points

Many dissolve in water

If melted or dissolved in water, they conduct electricity.