Module 2: Section 2

Question 1

How many electrons can the following sub-shells hold;

1. S sub-shell
2. P Sub-shell
3. D Sub-shell
4. F sub-shell

Answer 1

S Sub-shell = 2 electrons
P Sub-shell = 6
D Sub-shell = 10
F Sub-shell = 14

Question 2

What shapes are S orbitals and P orbitals?

Answer 2

S orbitals are spherical.

P orbitals are dumbbell shaped.

Question 3

When does ionic bonding occur?

Answer 3

Occurs between a metal & non-metal.

Question 4

Define ionic bond.

Answer 4

Ionic bond = electrostatic attraction between 2 oppositely charged ions.

Question 5

Describe a giant ionic lattice.

Answer 5

Made up of the same basic unit repeated over and over again.
Each ion is electrostatically attracted in all directions to ions of the opposite charge.
Strong ionic bonds means lots of energy is needed to break up the lattice.

Question 6

Give 3 behavioural characteristics of ionic compounds.

Answer 6

1. Conduct electricity when molten or dissolved, but not as a solid. As a liquid, the ions are mobile, but as a solid the ions are fixed in place by strong ionic bonds.
2. Ionic compounds have high mpts and bpts.
   Ionic lattices are held together by strong electrostatic forces, which require a lot of energy to be broken.
3. Ionic compounds tend to dissolve in water as water molecules are polar and are attracted to charged ions. They pull ions from the lattice and cause it to dissolve.

Question 7

When does covalent bonding occur?

Answer 7

Occurs between 2 non-metals.

Question 8

Define covalent bond.

Answer 8

Covalent bond = The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 9

Give an example of covalent bonding.

Answer 9

Cl2

Question 10

How do you measure the energy required to break a covalent bond.

Answer 10

Average bond enthalpy measures the energy required to break a covalent bond.

Question 11

What is dative covalent bonding?

Answer 11

Both electrons come from one atom.

Question 12

Why do electron pairs repel eachother?

What time of electron pairs repel more?

Answer 12

Electrons are all negatively charged, so repel as much as possible.
Lone pairs repel more than bonding pairs.

Question 13

Give the name and angle of a molecule with 2 electron pairs around the central atom.

Answer 13

180 degrees

linear molecules.

Question 14

Give the name and angle of a molecule with 3 electron pairs around the central atom.

Answer 14

120 degrees

trigonal planar.

Question 15

Give the name and angle of a molecule with 4 electron pairs around the central atom and no lone pairs.

Answer 15

109.5 degrees

tetrahedral

Question 16

Give the name and angle of a molecule with 4 electron pairs around the central atom and 1 lone pair.

Answer 16

107 degrees

trigonal pyramidol

Question 17

Give the name and angle of a molecule with 4 electron pairs around the central atom and 2 lone pairs

Answer 17

104.5 degrees

non-linear or bent

Question 18

Give the name and angle of a molecule with 5 electron pairs around the central atom and no lone pairs.

Answer 18

90 degrees

trigonal bipyramidol

Question 19

Give the name and angle of a molecule with 6 electron pairs around the central atom and no lone pairs.

Answer 19

90 degrees

Octrahedral

Question 20

Define electronegativity.

Answer 20

Electronegativity = an atoms ability to attract the electron pair in the covalent bond.

Question 21

What is the most electronegative element?

Answer 21

Fluorine.

Question 22

What makes a bond polar.

Answer 22

In a covalent bond, the bonding electrons are pulled towards the more electronegative atom. This makes the bond polar.

Question 23

What causes a permanent dipole-dipole.

Answer 23

In a polar bond, the difference in electronegativity between the 2 atoms causes a permanent dipol-dipole. Caused by a shift in electron density.

Question 24

What intermolecular forces do polar bonds have?

Answer 24

Permanent dipole-dipole.

Shift in electron density occurs due to the difference in electronegativity.

Question 25

Name the 3 types of intermolecular forces.

Answer 25

1. Induced dipole-dipole/ London forces / dispersion forces
2. Permanent dipole-dipole
3. Hydrogen bonding.

Question 26

What causes induced dipole-dipoles?

Answer 26

Electrons in charge clouds are always moving. At any moment electrons are to one side of the atom more than the other, creating a temporary dipole.
This dipole induces a dipole in neighbouring atoms, and so on, until a network of dipoles are created.
Dipoles are attracted to eachother as they are slightly charged.

Question 27

Why do some molecules have stronger induced dipole-dipole forces?

Answer 27

1. Large molecules have larger electron clouds, making the intermolecular forces stronger.
2. Molecules with a large surface area have a bigger exposed electron cloud, making the intermolecular forces stronger.

Question 28

When does hydrogen bonding occur?

Answer 28

Occurs when hydrogen is covalently bonded to fluorine, nitrogen or oxygen.

Question 29

Give 2 unusual properties or ice

Answer 29

1. Ice has an unusually high mpt due to hydrogen bonding.

2. Ice is less dense than water as it is held in a lattice shape by hydrogen bonds.

Question 30

Why do simple covalent compounds have a low mpts and bpts?

Answer 30

Intermolecular forces are weak, so dont need much energy to overcome .

Question 31

Why are polar molecules soluble in water?

Answer 31

Water is a polar molecules, so is attracted to charged ions in polar molecules, causing them to dissolve.

Question 32

Why dont simple covalent compounds conduct electricity?

Answer 32

The compounds are uncharged and so do not conduct electricity.

Question 33

Why dont simple covalent compounds conduct electricity?

Answer 33

The compounds are uncharged and so do not conduct electricity.