Inorganic Chemistry - Module 2

Question 1

Define ionisation energy.

Answer 1

The energy needed to form positive ions.

Question 2

What is the first ionisation energy of an element?

Answer 2

The energy needed to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.

Question 3

Do outer-shell electrons require the most or the least ionisation energy? Explain your answer.

Answer 3

They require the least ionisation energy. This is because they are further away from the nucleus and experience less nuclear attraction.

Question 4

Which three factors affect the nuclear attraction experienced by an electron?

Answer 4

Atomic radius, nuclear charge, and electron shielding/screening (inner shells of electrons repel outer-shell electrons).

Question 5

What is the second ionisation energy of an element?

Answer 5

The energy needed to remove an electron from a 1+ ion to form a 2+ ion.

Question 6

Define principle quantum number.

Answer 6

A number representing the relative overall energy of each orbital, which increases with distance from the nucleus.

Question 7

Define atomic orbital.

Answer 7

v

Question 8

What is the formula to work out how many electrons shells hold?

Answer 8

2n²

Question 9

Within a shell, state the number of s-, p-, d-, and f-orbitals.

Answer 9

• s = 1
• p = 3
• d = 5
• f = 7

Question 10

How many electrons can an orbital hold?

Answer 10

2

Question 11

Define sub-shell.

Question 12

Give the electron configuration in terms of sub-shells for Si (atomic number of Si = 14).

Answer 12

1s², 2s², 2p⁶, 3s², 3p²

Question 13

Give the electron configuration in terms of sub-shells for N^3- (atomic number of N = 7).

Answer 13

1s2, 2s2, 2p6

Question 14

Why are noble gases so unreactive?

Answer 14

They have full outer shells.

Question 15

Which type of compound does ionic bonding take place in?

Answer 15

Metal-Non Metal.

Question 16

Which type of compound does covalent bonding take place in?

Answer 16

Non metal-Non metal.

Question 17

Define ionic bond.

Answer 17

The electrostatic attraction between oppositely charged ions.

Question 18

Write the electron configuration for K and K⁺ (atomic number of K = 19)

Answer 18

K: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s¹

K⁺: 1s², 2s², 2p⁶, 3s², 3p⁶

Question 19

Define covalent bond.

Answer 19

A bond formed by a shared pair of electrons.

Question 20

Define a dative covalent/co-ordinate bond.

Answer 20

A shared pair of electrons which has been provided by one of the bonding atoms only.

Question 21

What is the bond angle in a water molecule?

Answer 21

104.5

Question 22

What is the bond angle in an ammonia molecule?

Answer 22

107

Question 23

Define permanent dipole.

Answer 23

A small charge difference across a bond due to the difference in electronegativities of the bonded atoms.

Question 24

Across the period table, does electronegativity increase or decrease?

Answer 24

Increases.

Question 25

What are the strongest bond types?

Answer 25

Ionic and covalent bonds.

Question 26

What is the weakest bond type?

Answer 26

Van der Waals' forces.

Question 27

Define Van der Waals forces.

Answer 27

Attraction between induced dipoles of neighbouring molecules.

Question 28

Where do hydrogen bonds form?

Answer 28

Between an electron-deficient H atom on one molecule and the lone pair of electrons on an O or N atom of another molecule.

Question 29

Give a diagram for hydrogen bonding.

Answer 29

Question 30

Define metallic bonding.

Answer 30

The electrostatic attraction between positive metal ions and delocalised electrons.

Question 31

Why do ionic compounds have high melting and boiling points?

Answer 31

Because of the strong electrostatic forces holding the oppositely charged ions together in a lattice structure.

Question 32

Why can't ionic compounds conduct electricity when solid, but can when molten or dissolved?

Answer 32

When solid, the ions are in a fixed position and can't move. However, when molten or dissolved, the ions can move, allowing them to conduct electricity.