Atomic Structure: Ionisation energy

Question 1

When does ionisation occur?

Answer 1

when an atom gains or loses electrons

Question 2

What is ionisation energy?

Answer 2

energy required to remove one mole of electrons from one mole of gaseous atoms of an element

Question 3

what type of process is ionisation?

Answer 3

endothermic process (putting in energy to remove an electron)

Question 4

what is the first ionisation energy?

Answer 4

energy required to remove one electron from an atom in one mole of gaseous atoms producing one mole of 1+ gaseous atoms

Question 5

name three factors affecting 1st IE

Answer 5

• nuclear charge
• distance from nucleus
• shielding

Question 6

why does nuclear charge affect 1st IE?

Answer 6

• more protons= more positively charged nucleus

- electrons are more strongly attracted to nucleus

Question 7

why does the distance from the nucleus affect 1st IE?

Answer 7

• the further away the electron, the less attraction and less tightly held in

Question 8

why does shielding affect 1st IE?

Answer 8

• more electrons between outer electrons and nucleus, the easier to remove due to less attraction

Question 9

what is the trend of 1st IE as you go down a group?

Answer 9

• decreases down a group
• electron to be removed from outer energy level is increasingly distant from nucleus
• more energy levels =shielding so inner electrons reduce attraction of nucleus to outer electrons

Question 10

what is the trend of 1st IE as you go across a period?

Answer 10

• increases across a period
• increase of nuclear charge due to more protons added to nuclei of atoms
• electrons in outer energy level more tightly held and more difficult to remove

Question 11

how does the electron arrangement of Al affect the 1st IE in period 3 between group 2 and 3?

Answer 11

• although has increased nuclear charge, its outer electron is in a 3p orbital
• slightly higher energy than 3s orbital so less energy needed to remove electron (further away from nucleus)
• more shielding - easier to remove electron

Question 12

how does the electron arrangement of S affect the 1st IE in period 3 between group 5 and 6?

Answer 12

sulfar atom has a 3p orbital occupied by two electrons so repulsion between two electrons means that it is easier to remove from orbital

Question 13

what are successive ionisation energies?

Answer 13

energies required to remove the electrons one by one starting from outer electrons and working inwards

Question 14

why do successive ionisation energies increase?

Answer 14

electrons are removed from increasingly positive ion so less repulsion meaning stronger attraction

Question 15

what is the second ionisation energy?

Answer 15

energy required to remove an electron from a 1+ ion in a mole of gaseous 1+ ions

Question 16

what is the third ionisation energy?

Answer 16

energy required to remove an electron from a 2+ ion in a mole of gaseous 2+ ions