Covalent Bonding

Question 1

When does covalent bonding take place ?

Answer 1

When two non metals react

Question 2

Process of a simple covalent bond.

Use hydrogen as an example H2

Answer 2

Hydrogen has 1 electron in its outer shell , however in the first shell it requires two electrons for the shell to be full.

It this case it achieves this by bonding with another hydrogen atom.

The two hydrogen atoms overlap their outer energy shells to share their electrons. They now both have two electrons (full outer shell)

They have formed a simple covalent bond.

Question 3

How can we represent covalent bonds.

Answer 3

Energy level diagram

Dot and cross

Stick diagram - line represents the covalent bond

Question 4

Describe the bonding between hydrogen and chlorine.

Show the stick diagram.

Answer 4

Hydrogen - 1 electron in outer shell
Chlorine - 7 electrons in outer shell

They overlap their shells to share one electrons each giving each element a full outer shell.

Can be represented by H-Cl

Question 5

Covalent bond of water include stick diagram

Answer 5

Contain 2 atoms of hydrogen and 1 atom of oxygen

Oxygen - 6 electrons in outer shell ( two required )
Hydrogen- 1 electron in outer shell ( 1 required )

Can be achieved by both the hydrogen atoms and the oxygen atom overlapping. Visual shown by stick diagram

   O              NEED LINES TO CONNECT          WHEN DRAWING AS ENERGY LEVEL PUT EITHER SIDE OF OXYGEN    H      H

Question 6

Covalent bond of Ammonia NH3 include stick diagram

Answer 6

Contain 1 atom of nitrogen and 3 atoms of hydrogen

Nitrogen - 5 electrons in outer shell ( requires 3 )
Hydrogen- 1 electron in outer shell (requires 1 ) PER HYDROGEN ATOM, REMEMBER THERE ARE 3

Each hydrogen atom overlaps with the nitrogen atom providing it with 3 electrons and they each gain 1.

H - N - H SAME FORMOT AS ENERGY LEVEL DIAGRAM BUT WITH THE ATOMS DRAWN
|
H

Question 7

Covalent bond of Methane CH4 include stick diagram

Answer 7

Contains 1 atom of Carbon and 4 atoms of Hydrogen

Carbon - Has 4 electrons in the outer shell ( requires 4 )
Hydrogen - Has 1 electron in the outer shell ( requires 1 ) PER ATOM, THERE IS 4 IN METHANE

        H
        |
 H  - C - H        ENERGY LEVEL DIAGRAM IS THE SAME STRUCTURE WITH ATOMS DRAWN
        |
        H

Question 8

Covalent Bonding in an oxygen molecule (O2)

Answer 8

Contains two atoms of oxygen

Oxygen - 6 electrons in outer shell (requires 2) PER ATOM

They overlap their outer energy shells forming a double covalent bond with 2 electrons being shared from each atom.

Drawn as stick diagram as O O with two lines in between.

Question 9

Covalent bonding in a nitrogen molecule (N2)

Answer 9

Contain 2 nitrogen atoms

Nitrogen - 5 electrons in their outer electron shell ( requires 3 ) EACH

They do this by overlapping their shells to share 3 electrons each creating a triple bond. Or three shared pairs

Represented as N N with three lines in between

Question 10

Properties of small covalent molecules

Answer 10

1) Low melting and boiling points - usually gases or liquids at room temperature
Atoms in each molecule are held together by strong covalent bonds
There are very weak intermolecular forces between molecules - not much heat energy required to break them

2)They do not conduct electricity - small covalent molecules do not have an overall charge