At the end of this lesson we will be able to understand :-

Why an atom gets bonded with other atom or atoms.

Different types of solids depending upon type ofbonding between their particles.

Properties of different solids.

Group zero elements

Element Electronic configuration

Behavior of atoms

2He4 2 Helium atoms do not bond

10Ne20 2 , 8 Neon atoms do not bond

18Ar40 2 ,8, 8 Argon atoms do not bond

Argon: 18Ar40

Nucleus

First shell: 2electrons

Second shell : 8 electrons

Third shell : 8 electrons

Each shell is full .

Magnesium :12 Mg24

Nucleus

First shell ; 2 electrons

Second shell : 8 electrons

Third shell : 2 electrons

Outer shell not full : only 2 electrons in it

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Now I am sure you can tell me that why bonding takes place between two atoms.

Types of solidsDepending on the type of bonding solids

are of Four types – Molecular solids Macromolecular solids Metallic solids Ionic solids

I I

I I

Two atoms of iodine

Two atoms bonding together

Iodine : a molecular solid

I I

Two Iodine atoms

I I

An Iodine molecule

I - I

A covalent bond between two Iodine atoms is formed

I I I I

I I

A Collection of iodine atoms Iodine molecules, full shells

I I

C C

C

C

C

Carbon is in IV group –each atom has 4 outer shell electron

Carbon (diamond) : a macromolecular solid

C

CC

C C

Central carbon atom now has a full outer shell

Carbon lattice

The whole lattice is held together by covalent bonds. These are strong forces of attraction, so a considerable amount of energy is needed to break up the lattice.

Lattice of iodine molecules

The forces of attraction between molecules is weak , however – they all have full shells – so lattice is easily broken up.

sodium atom Na

sodium ion Na+

11 protons, 11 electrons: neutral 11 protons, 10 electrons:+ charged

Sodium : a metallic solid

Removed electron

repulsion

attraction

Metallic Bonding

Metal ion

- Delocalized electron

Metals are malleable and ductile : they can be bent , shaped and drawn into wires.

Force applied

delocalized electrons moving though the lattice carrying negative charge

Metals conduct electricity well

HOT ENDCOLD END

ELECTRONS MOVING QUICKLY

ELECTRONS MOVING SLOWLY

Metals conduct heat well

Na

Cl Cl

Na+

-

atoms ions

Salt : an ionic solid

Electrovalent bond between cat ions and anions

cat ion

anion

repel

Force applied

Although ionic solids are hard , they are brittle. They shatter when hit by a hammer.

+

++

+

+

+

+

+

+

+

-----

----

electrode electrode

solvent particles

Summary• Properties of a solid depend on the type of particle

in the lattice & the way in which they attract each other in the lattice.

• There are three types of bonding – covalent bonding, metallic bonding, ionic bonding .

• In all these bonding, the atoms achieve full electron shells .

• An ion is a particle which has gained or lost electrons, so is charged .