ionisation energy

What is the other name for ionization energy

Ionisation enthalpy

Why is ionization an endothermic process

It takes energy to overcome attraction between electrons and nucleus

What do lower ionization energies mean

The lower it is the easier it is to form an ion

What is first ionization energy

The energy needed to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1± ions

Define second ionization energy

The energy needed to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

General equation for ionisation energy

3 factors affecting ionisation energy

Distance from nucleus –> electrons closer = more strongly attracted

Nuclear charge –> more protons in nucleus=more positively charged=stronger attraction to electrons

Shielding –> screening from increased electrons and shells between nucleus and outer electrons decreases attraction

What is ionisation energy measured in

KJmol‐¹

How can you use a graph of successive ionization energy to identify the group number

The number of electrons removed before the first big jump is the group number because it's the number of electrons in the outer shell

How can you use a graph to identify the number of electrons per shell

The number of electrons between jumps

Why does successive ionization energies increase within each shell

Electrons are being removed from an increasingly positive ion so there's less repulsion amongst the remaining electrons so they are held more strongly by the nucleus

Why are there big jumps in the ionization energy

When a new shell is broken into an electron is being removed from a shell closer to the nucleus requiring more energy because nuclear pull is stronger

Generally what happens to first ionization energy down a group

Decreases

Generally what happens to first ionisation energy across a period

Increases

What is ionization energy typically decrease down a group

Easy to remove outer electrons because each element going down the group has an extra shell increasing shielding of outer shells from the nuclear attraction and increasing the distance of the outer electron from the nucleus decreasing nuclear attraction

What does the decreasing of ionization energy down a group help to prove

Electron shells exist and successive elements down the group have extra, bigger shells

Why does ionization energy generally increase across a period

It gets harder to remove the outer electron because proton number increases increasing nuclear attraction, and pulling in remaining electrons reducing atomic radius with the shielding effect reduced despite the fact that the outer electrons are in different orbital types because they are all at roughly the same energy level

Despite the general trend in ionization energies where would you find the drops

Between groups 2 and 3 AND 5 and 6

Why is there a drop from Group 2 to 3

You are going from the outer electron being in a 3s orbital to a 3p orbital which is slightly higher energy so the electron is found to be further from the nucleus and there is increased shielding from the 3S² electrons overriding the effect of increased nuclear charge causing a drop in the trend

What does the drop from Group 2 to 3 provide evidence of

Electronic subshells

Why is there a drop from group 5 to 6

They are having electrons removed from the same orbital but those in group 5 are having one removed from a singly occupied orbital while those in group 6 have a spin pair in the orbital losing one and the repulsion between the two electrons in an orbital in a spin pair makes electrons in shared orbitals easier to remove