Ionisation Energy

Question 1

In shorthand notation where do you start the notation of electrons

Answer 1

The element that is at the end of the period + From the last orbital being filled eg
Na - [Ne] 3s2

Question 2

Why is sodium is an s-block element?

Answer 2

An element which the last vance electron fills an s-orbital

Question 3

Define periodicity

Answer 3

Describing a repeating pattern of properties of elements across periods of the periodic table.

Question 4

What is the periodic table arranged in terms of

Answer 4

• Increasing atomic / proton number
• Periods showing repeated trends e.g Physical and Chemical
• Groups having similar physical and chemical properties

Question 5

Define first ionisation energy

Answer 5

The energy required to remove 1 mol of electrons from 1 mol of gaseous atoms

Question 6

Write and equation to represent the first ionisation energy

Answer 6

X+(g) -> X2+(g) + e-

Question 7

What is the trend in successive ionisation energy’s of any atom

Answer 7

As you remove electrons closer to the nucleus , the more energy is required, due to stronger nuclear attraction.

Question 8

Explain how successive ionisation energy of X can show the electron shell structure

Answer 8

There is a large difference between the Xth and Yth ionisation energy . This means there are Z shells

Question 9

State the 3 factors that affect ionisation energy and describe each factor

Answer 9

• Size of nuclear charge - The more protons in the nucleus the stronger the attraction of electrons
• Distance of electrons from the nucleus - Attraction falls of rapidly w/ distance
• Nuclear attraction to electron - inner shell repel outer shell of electrons , thereby attraction between the outer shell

Question 10

There is a general increase in the first ionisation energy’s across period X, Explain why?

Answer 10

• Nuclear charge increases
• Electrons added to the same shell
• Greater attraction on the outermost electron to the nucleus
• More energy is required to remove an electron

Question 11

What is the first exception for the first ionisation energy

Answer 11

• Al has a lower first ionisation energy than that of Mg even though it has a higher nuclear charge
• This is because the electron removed from Al is in a higher 3p sub level , which means it has a higher energy level than the 3S electron in Mg so it requires less energy to remove

Question 12

What is the second exception for the first ionisation energy

Answer 12

• X has a single electron pair in each p orbital
• Y has an electron that is a spin pairing
  In Y this spin pairing leads to repulsion, so less energy is required to remove an electron

Question 13

General explanation

Why is the first ionisation energy of strotium larger than the first ionisation energy of rubidium

Answer 13

• Sr has a greater nuclear charge
• The more protons in the nucleus the stronger the attraction of electrons

Question 14

General explanation

Why is the second ionisation energy of rubidium larger than the second ionisation energy of rubidium

Answer 14

Rb involves removing an electron from a shell from a closer to the nucleus
Stronger attraction on the outermost electron of Rb which requires more energy to remove

Question 15

Same element

Why is the second ionisation energy of oxygen a greater value than the first ionisation energy

Answer 15

The proton : electron ratio in the 1+ ion is greater than in the atom

Question 16

Explain the general trend down the group of the first ionisation energy

Answer 16

• Decrease
• As there is More shells
• More sheilding
• Distance and shielding outweigh the increased nuclear charge
• Less attraction on the outermost electron from the nucleus
• Less energy is required to remove an electron