2.2.1: Electron structure & ionisation energy

Question 1

Ground state

Answer 1

the lowest energy level available to the electron.

Question 2

Energy levels converge where?

Answer 2

At n =∞

Question 3

The higher the n…

Answer 3

the further the shell is from the nucleus

∴ the higher the energy in that shell

Question 4

First ionisation energy

Answer 4

• Energy required
• To remove 1 mole of electrons
• From 1 mole of gaseous atoms
• To form 1 mole of gaseous unipositive cations

Question 5

Equation for first ionisation energy

Answer 5

X (g) –ΔH–> X⁺ (g) + e-

Question 6

Factors that affect ionisation energy

Answer 6

• Nuclear charge
• Shielding
• Atomic radius (distance from nucleus)

Question 7

Nuclear charge effect on ionisation energy

Answer 7

• Greater +ve charge (no. of protons) = harder to remove e-
∵ there is greater electrostatic attraction between e- and nucleus
• Hence greater nuclear charge = higher ionisation energy

Question 8

Shielding effect on ionisation energy

Answer 8

• Electrons repel each other
• Electrons in inner shells repel those in outer shells –> reduces EFFECT OF +ve charge of the nucleus
• Greater shielding = lower ionisation energy

Question 9

Atomic radius effect on ionisation energy

Answer 9

• Attractive force inversely proportional to distance squared (Coulomb’s law of electrostatics)
• Greater distance = weaker attractive force = lower ionisation energy

Question 10

Trends in 1st IE

Answer 10

1st IE:
↓ down group due to shielding
↑ across a period due to increasing nuclear charge

Question 11

1st IE ______ down a group

Answer 11

decreases

Question 12

1st IE _______ across a period

Answer 12

increases

Question 13

Why does 1st IE decrease down a group

Answer 13

Due to increasingly shielding

Question 14

Why do successive ionisation energies always increase?

Answer 14

• Because electrostatic attraction between e- and nucleus increases
• Because e- is gradually being removed from a more +ve species

Question 15

Orbital

Answer 15

A probability region for an electron.

Question 16

s subshell

Answer 16

• spherically symmetric
• 1 x orbital which holds 2 e-
• Starts at n=1

Question 17

p subshell

Answer 17

• Starts at n=2

* Each subshell has 3 orbitals (2e- each)

Question 18

All the p orbitals in a p subshell are __________

Answer 18

degenerate

Question 19

d subshell

Answer 19

• starts at n=3

* Each subshell has 5 orbtials (2e- each)

Question 20

f subshell

Answer 20

• starts at n=4

* Each subshell has 7f orbitals

Question 21

Rules for electron configuration

Answer 21

1) Each orbital can hold max 2 e- (Pauli)
2) Orbitals are occupied in order of increasing energy (Aufbau)
3) When more than one orbital of same energy available, orbitals are first occupied single (Hund’s rule)

Question 22

Trends in successive IE; consider:

Answer 22

• Is the electron being removed from a new quantum shell –> harder
• If the electron spin-paired with another e- in the same orbital –> they will still repel, it will be easier to remove 1 e- than expected

Question 23

Most energetically stable electron configuration:

Answer 23

• Most energetically stable = full subshells, all electrons spin paired
• Next most stable = half full shells (occupied singly with electron spins aligned)

Question 24

In what state can atoms be ionised?

Answer 24

Gaseous