ELECTRONS AND BONDING

Question 1

What are shells?

Answer 1

Shells are regarded as energy levels, the energy increases as the shell number increases.

Question 2

What is an atomic orbital?

Answer 2

An atomic orbital is a region around the nucleus that can hold up to two electrons of opposite spins.

Question 3

How many sub-shells are there and how many electrons can fit in one shell?

Answer 3

1 = 2
2 = 8
3 = 18
4 = 32

Question 4

What are the four different types of orbitals?

Answer 4

s-, p-, d- and f-

Question 5

What shape is an s-orbital and how many electrons can it fit?

Answer 5

It has a spherical shape and it can fit two electrons.

Question 6

What shape is a p-orbital and how many electrons can it fit?

Answer 6

A p-orbital has a dumbell shape (hourglass) and it has three seperate p-orbitals at right angles to each other: px, py, pz. Each p-orbital can contain up to 2 electrons and therefore 6 electrons in total. P-orbitals have 3 sub-shells.

Question 7

How many electrons can fit in a d-orbital?

Answer 7

10

Question 8

How many electrons fit into each orbital?

Answer 8

s = 2
p = 6
d = 10
f= 14

Question 9

What is unusual in the filling of orbitals?

Answer 9

4s goes before 3d because 3d has more energy than 4s.

Question 10

Why does an orbital have to have opposite spins?

Answer 10

Because electrons are negatively charged and repel one another and so need to have opposite directions (up and down). The opposite spins help to counteract the repulsion between electrons.

Question 11

How are orbitals occupied in a sub-shell?

Answer 11

They are occupied singly first to avoid any repulsion.

Question 12

What is the equation for the reaction between aluminium and fluorine?

Answer 12

2AL + 3F2 -> 2AlF3

Question 13

What is an ionic lattice?

Answer 13

A repeating pattern of oppositely charged ions.

Question 14

What is meant by the term covalent bonds?

Answer 14

A shared pair of electrons

Question 15

Do metals conduct electricity when molten or solid?

Answer 15

Both because they have delocalised electrons.

Question 16

What is ionic bonding?

Answer 16

The electrostatic attraction between oppositely charged ions.

Question 17

What is covalent bonding?

Answer 17

Covalent bonding is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom. This is within non-metals.

Question 18

Do ionic bonds conduct electricity when solid or molten?

Answer 18

They conduct electricity when molten because they have mobile ions. They don’t conduct electricity when solid because they have ions in fixed positions and in an ionic lattice.

Question 19

Do covalent bonds conduct electricity when molten or solid?

Answer 19

No because they have no mobile charge carriers.

Question 20

What is the trend in group 3 (attraction between the nuclei and outermost electrons)?

Answer 20

The attraction between the nuclei and outermost electrons increases, the atomic radius decreases and the number of protons increases.

Question 21

What are London forces used to describe?

Answer 21

Induced dipole-dipole interactions

Question 22

What are Van der waals forces used to describe?

Answer 22

induced and permanent dipole interactions

Question 23

What are dipole-dipole interactions?

Answer 23

Attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.

Question 24

What is the difference between induced and permanent dipole-dipole interactions?

Answer 24

Induced dipole-dipole interactions happen within all molecules whereas permanent only occurs in polar molecules.

Question 25

What is the bond enthalpy for induced, permanent dipole-dipole interactions and hydrogen bonds?

Answer 25

induced dipole-dipole- 1
Permanent dipole-dipole- 10
Hydrogen bonds - 50

Question 26

What is bond enthalpy?

Answer 26

Bond energy

Question 27

What influences IDDI?

Answer 27

The random movement of electrons

Question 28

What is the correlation between boiling point and London forces?

Answer 28

The higher the boiling point, the stronger and more the London forces.

Question 29

Give two anomolous properties of ice?

Answer 29

Ice is less dense than water because molecules in ice are held apart by hydrogen bonds.

Ice has a relatively high melting point because hydrogen bonds are relatively strong.