Ionisation energy

Question 1

first ionisation energy

Answer 1

The minimum amount of energy to remove one moles worth of electron from one moles worth of gaseous atom

Question 2

second ionisation energy

Answer 2

The minimum amount of energy to remove one moles worth of electron from one moles worth of gaseous ion

Question 3

why does the first electron that is removed need less energy

Answer 3

it comes from a neutral atom

Question 4

how can they be removed

Answer 4

electron guns

Question 5

General trend across periods

Answer 5

increasing

Question 6

why does it generally increase

Answer 6

nuclear charge increases by 1. Electrons are in the same shells therefore shielding stays the same. Atomic radius decreases.

Question 7

evidence for principle energy levels

Answer 7

e.g.ne-na and he-li. Na has a significantly lower IE than Ne. Because Na’s outer e is in the third shell, therefore it is further away from the nucleus and more shielded.

Question 8

evidence for sub levels s+p

Answer 8

e.g. Be-B and Mg-Al. B has a lower IE than Be. In B the outermost e is in the 2p sub level, in Be its in the 2s. The 2p electron is further away from the nucleus(higher energy), therefore more shileind for the ape and this come from the 2se.

Question 9

Evidence for orbitals

Answer 9

e.g.O-N. in Oxygen there are 2 e sharing a 2p orbital. These repel each other therefore less energy is required for ionisation.

Question 10

Explain why the ionisation energy of every element is endothermic.

Answer 10

Heat or energy needed to overcome the attraction between the (negative) electron and the (positive) nucleus or protons

Question 11

This question is about the first ionisation energies of some elements in the Periodic Table.Write an equation, including state symbols, to show the reaction that occurs when the first ionisation energy of lithium is measured.

Answer 11

Li(g) —->Li+(g) + e-(g)

Question 12

State and explain the general trend in first ionisation energies for the Period 3 elements aluminium to argon.

Answer 12

IncreasesIncreasing nuclear charge / increasing no of protons* Same or similar shielding / same no of shells /electron (taken) from same (sub)shell / electron closer to the nucleus / smaller atomic radius

Question 13

There is a similar general trend in first ionisation energies for the Period 4 elements gallium to krypton.State how selenium deviates from this general trend and explain your answer.How selenium deviates from this trend

Answer 13

LowerPaired electrons in a (4) p orbital(Paired electrons) repel

Question 14

Suggest why the first ionisation energy of krypton is lower than the first ionisation energy of argon.

Answer 14

Kr is a bigger atom / has more shells / more shielding in Kr / electron removed further from nucleus/ electron removed from a higher (principal or main) energy level

Question 15

Complete the electron configuration of the Mg+ ion.1s2……………..

Answer 15

2s2 2p6 3s1

Question 16

State the meaning of the term first ionisation energy.

Answer 16

Energy/enthalpy (needed) to remove one mole of electrons from 1 one mole of atoms/compounds/molecules/elementsorEnergy to form one mole of positive ions from one mole of atoms

Question 17

Explain why the second ionisation energy of magnesium is greater than the first ionisation energy of magnesium.

Answer 17

Electron being removed from a positive ion (therefore need more 1 energy)/ electron being removed is closer to the nucleus/Mg+smaller (than Mg)/Mg+ more positive than Mg