Evidence for Energy Levels - Atomic Structure (3.1)

Question 1

How are electrons arranged in atoms?

Answer 1

• Electrons in different shells have different energies

- The electrons closest to the nucleus have the lowest energy

Question 2

Describe the absorption spectra

Answer 2

• Energy of the light is absorbed and the electrons are excited to a higher energy level
• The energy absorbed corresponds directly to ΔE (energy difference between different energy levels)

Question 3

Describe the emission spectra

Answer 3

• Energy of the light is absorbed and the electrons are excited to a higher energy level
• Electrons fall back down to ground state and energy is released
• This energy emitted corresponds directly to ΔE (energy difference between different energy levels)

Question 4

What happens in ionisation?

Answer 4

With enough energy, the electron can be excited so far that it is removed from the atom, forming a positively charged ion

Question 5

Define first ionisation energy

Answer 5

The energy required to remove one mole of electrons from one mole of gaseous atoms

Question 6

Give 2 factors that affect ionisation energy

Answer 6

Atomic radius

Shielding

Question 7

Explain how a larger atomic radius affects ionisation energy

Answer 7

Larger atomic radius:

• The outer electron is further from the nucleus
• Weaker electrostatic attraction
• Easier to remove
• Therefore, ionisation energy decreases

Question 8

Explain how shielding affects ionisation energy

Answer 8

Increase in shielding:

• More repulsion from inner electrons
• Easier to remove outer electron
• Therefore ionisation energy decreases

Question 9

Define second ionisation energy

Answer 9

The energy required to remove 1 mole of electrons from 1 mole of singularly charged cations (+1 -> +2)

Question 10

Define third ionisation energy

Answer 10

The energy required to remove 1 mole of electrons from 1 mole of gaseous doubly charged cations (+2 -> +3)

Question 11

Explain why ionisation energy increase for Mg (1st, 2nd, 3rd etc. )

Answer 11

Requires more energy to remove electrons because Mg+ is smaller & charged

Question 12

Give evidence for energy levels from a graph showing successive ionisation levels of an element

Answer 12

Large jumps where shielding decreases between energy levels

easier to remove an electron from an energy level with only one outer electron than one with a full outer energy level