pericodity ionisation energy

Question 1

What is meant by the first ionisation energy

Answer 1

The energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms

Question 2

why is the first ionisation energy always endothermic

Answer 2

because either requires energy

Question 3

what is the equation for the first ionisation of potassium

Answer 3

K(g) → K+(g) + e–

Question 4

first ionisation energy down a group

Answer 4

• more shells
• more shielding
• less nuclear attraction
• Easier to remove an electron so less energy needed

Question 5

first ionisation energy across a period

Answer 5

• Same number of shells.
• Same shielding
• Higher nuclear attraction due to extra protons in nucleus
• Harder to remove an electron so more energy needed

Question 6

explain why the first ionisation energy of Berilyum is higher than the first ionisation energy of lithium

Answer 6

Electron is harder to remove from beryllium/ electron is easier to remove from lithium

ithium and beryllium are in the same period but Beryllium has an extra proton

Beryllium greater nuclear attraction to the electron

Question 7

explain the trend in period 3 group 2-3
why is there a dip?

Answer 7

think about electronic configuration

• For Al, the electron is being removed from a p sub shell, while mg is from an s sub shell
• P sub shells have more energy and is easier to remove

Question 8

explain the trend in period 3:
group 5-6
why is there a dip?

Answer 8

• for sulphur two electrons in same orbital
• negative electrons repel each other
• one negative gained energy and is easier to remove

Question 9

explain why the first ionisation energy is of group 1 elements in table 2 decreases as atomic number increases
atomic n 1st ionisation e
lithium 3 520
sodium 11 496
potassium 19 419

Answer 9

outer electrons are further away from nucleus
there is more sheilding
nuclear attraction decreases
less energy is required to remove outer electrons

Question 10

1st electron affinity for
Li
O

Answer 10

Li(g)+e − →Li

O(g)+e −→O −

Question 11

ionisation energy across a period and group

Answer 11

across a period increases
down a group decreases

Question 12

what does electron affinity mean

Answer 12

the energy change that results from adding an electron to a gaseous atom