Covanent Bonding

Question 1

What is covalent bonding and valence theory ?
What does double and triple covalent bond mean?

Answer 1

Valence theory=the consequence of overlapping of atoms due to sharing electrons
1)A pair of electrons shared between atoms (one pair= single covalent bond)
2) double covalent bond = has TWO pairs of electrons shared e.g. oxygen
3)triple covalent bond= shares THREE pairs of electrons e.g. aluminum

Question 2

What elements can expand their outer shell and into where ?

Answer 2

Some atoms can expand their outer shell (has more than 8 electrons) specifically elements in period 3 on going and they move into the 3d subshell

Question 3

How does the repulsion between the two positively charged nuclei not affect the covalent bond?

Answer 3

The negative charged electrons are attracted to the positive charges of both nuclei
however the attraction overcomes the repulsion between the two positively charged
nuclei, so they are covalently bonded

Question 4

What are lone pairs ?

Answer 4

Pair of electrons in the outer shell which are not involved in the chemical bonding. (nonbonding electr

Question 5

What are vacant orbitals?

Answer 5

Vacant orbitals can be involved in bonding.
They are orbitals that are not currently occupied by any electrons in an atom or molecule

Question 6

What are dative covalent/co-ordinate bonds? And how can they be written as?

Answer 6

Contains a shared pair of electrons with both electrons supplied by only one atom.
They can be written as A–>B with the arrow showing the direction the donated pair of electrons moved in

Question 7

What are the two types of covalent structures and give brief description of each and examples?

Answer 7

=
1) Macromolecular (giant covalent structures)
Many strong covalent bonds forming giant structures
Its physical properties are affected by the strong covalent bonds.
Examples= graphene, graphite, diamond, silica
2)(simple )molecular
A small number of covalent bonds form a small molecule.
Physical properties are affected by intermolecular forces between the other molecules.

Question 8

What are 4 types of crystal structures?

Answer 8

Ionic
Metallic
Macromolecular
Molecular

Question 9

Give me two examples of macromolecular structures.
-conduct electricity,bonds,meting /boiling points

Answer 9

Diamond =macromolecular, each carbon atom bonds to 4 other carbon atoms, does not
conduct electricity as it has no delocalized electrons, has a high melting point as alot of
energy is needed to overcome the strong covalent bonds.

Graphite= macromolecular, each carbon bonds to 3 other carbon atoms, DOES conduct
electricity when melted as it has layers and delocalized electrons. It has a very high melting
point as a lot of energy is needed to break the covalent bonds.

Question 10

Give me one example of a molecular structure?
Meting/boiling point ,conductivity,solubility

Answer 10

Iodine(I2) = molecular, not a lot of energy is needed to overcome the weak intermolecular
forces (Interactions) so low melting point. It cannot conduct electricity as it has no
delocalized electrons. It is insoluble in polar (slightly charged) solvents e.g. water as it has
no overall charge.

Question 11

One example of ionic structure ?
What is it ?
Can it conduct electricity?
Melting /boiling pt?

Answer 11

Sodium chloride=it is a giant ionic lattice structure, can conduct electricity when molten or
dissolved in solvent, has a high melting point as a lot of energy is needed to overcome the ionic bonds