Ionisation energy

The second ionisation energy is the energy required to remove one moles of electrons from one mole of gaseous 1+ positive ions to form one mole of gaseous 2+ positive ions

Away is the second ionisation energy?

Because a more positively charged ion has to be overcome

Give one sentence to say why the value of successive ionisation energies increase across a period.

The more protons that are in the nucleus, the more positively charged the nucleus is and so the stronger the attraction between the nucleus and the electrons

How does nuclear charge affect ionisation energy?

As the number of electrons between the outer electrons and the nucleus increases, the outer electrons will feel less attraction to the nucleus. This lessening of the pull of the nucleus thanks to the electrons on inner shells is called shielding

How does shielding affect ionisation energy?

Attraction falls of rapidly with distance. The closer an electron is to the nucleus the stronger the attraction so the more energy needed to remove the electron.

How does the distance of the electron from the nucleus affect ionisation energy?

The more periods an atom has the bigger the atom will be so the outer electron will be further away from the nucleus and it require less energy to remove so it will have a lower ionisation energy

If attraction falls of with distance, what does this mean for the ionisation energy of elements in periods 4-5?

The gas state symbol, (s) must always be used, because ionisation energies are measured for gaseous atoms

In ionisation equations, what must always be used and why?

An endothelium process because you have to put energy in to remove an electron from an atom or molecule (more energy is taken in during bond breaking than is given our during bond making)

Is ionisation in the sense of ionisation energy (removing electrons) an exothermic or an endothermic process?

The more shielding the lower the ionisation energy because the electrons between the outer electron shell and the nucleus will lessen the pull of the attraction of the curls I towards the outer electron so less energy will be required to remove an electron

The more shielding...

Removing all the electrons from an atom, leaving just the nucleus. Each time you remove an electron, there's a successive ionisation energy e.g. First, second, third, fourth etc..

What are successive ionisation energies?

A high ionisation energy means there's a strong attraction between the outer electron and the nucleus so more energy is required to remove an electron

What does it mean for the attraction between the nucleus and the outer electron if there's a high ionisation energy and what does this mean?

Nuclear charge, the distance of the electron from the nucleus and the shielding effect of inner electrons

What does the value of the second ionisation energy depend on?

Atomic radius decreases as you cross a period

What happens to atomic radius as you cross a period?

A lower ionisation needy means less energy is required to remove an electron - it's easier to remove an electron

What is meant by a lower ionisation energy?

When electrons have been removed from an atom or molecule

What is meant by ionised?

The first ionisation energy is the energy needed to remove one mole of electrons from one mole of gaseous atoms to form one mole of positive 1+ gaseous ions

What is the first ionisation energy?

When you compare atoms with outer electrons the same distance from the nucleus and with equal shielding effects. This happens with elements that are in the same period of the periodic table

When can you see the effect of nuclear charge on ionisation energy?

When anew shell is broken into

When do big jumps in ionisation energy occur?

The successive ionisation energy that removes the electron closest to the nucleus because there will be stronger nuclear attraction and no shielding effect as there will be no other electrons as it would be the last electron to be removed

Which successive ionisation energy will be the highest?

Because the electron is being removed from a positive ion which will require more energy. This is because the second electron removed from an atom could come from a shell with a lower quantum number so the electron being removed would be closer to the nucleus so it would have a stronger nuclear attraction. Also if the second electron being removed comes from an energy level from a lower quantum number, there will be less shielding effects because the electron will be on the shell than previously shielded the first outer electron. This means that the second ionisation energy is much higher than the first ionisation energy

Why are second ionisation energies greater than first ionisation energies?

This is because electrons are being removed from an increasingly positive ion - there's less repulsion amongst the remaining electrons so they're held more strongly by the nucleus. The electrons being removed are closer and closer to the nucleus so the nuclear attraction is stronger and they have less shielding effects.

Why do successive ionisation energies increase within each shell?

Ionisation energy decreases down a group because the outer electron becomes further away from the nucleus as there are more shells being added (crossing periods) and therefore the outer electron is less strongly attracted

Why does ionisation energy decrease down a group?

As a period is crossed, the nuclear charge increases but electrons are added to the same outer shell and do not shield each other from the extra nuclear charge (the nucleus is becoming more positive). This means it requires more energy to remove the outer electron as it is more strongly attracted to the nucleus

Why does ionisation energy increase across a period?

Because group 1 elements only have one electron in their outer shell so they want to lose it and become a stable ion with a full outer shell of electrons.

Why have group one elements got the lowest ionisation energy?

Mg -3s little 2 Al - 3p little 1 It requires less energy to remove an electron of aluminium than of magnesium because the outer electron In magnesium is in a higher energy level so it is slightly more distant from the nucleus, meaning there is a weaker nuclear attraction between the outer electron and the nucleus than in magnesium. Also the 3p electron has slightly more shielding by the 3s electrons so this lessens the force of the nuclear attraction. These two factors are strong enough to override the facet of nuclear charge, resulting in the ionisation energy for aluminium being slightly lower than magnesium's.

Why is it easier to remove an electron from aluminium than from magnesium?

Phosphorus - 3p little 3 Sulphur - 3p little 4 The electron in phosphorus is being removed from a singly-occupied orbital, but in sulphur the electron is being removed from an orbital contains two electrons. The repulsion between the two electrons in the orbital means it is easier to remove one of the electrons in the pair so sulphur has a lower first ionisation energy

Why is it easier to remove an electron of sulphur than of phosphorus?

Noble gases have a high ionisation energy because they already have a full outer shell of electrons so they don't want to lose any

Why is it hard to remove electrons from noble gases?

All the electrons are at roughly the same energy level, even if their outer l electrons are in different sub-shells. This means there's generally little extra shielding effect or extra distance to lessen the attraction between p the nucleus and the outer electron

Why is there generally little extra shielding across a period?

Because as you go across a period, an electron is added to the outer shell, so the number of electrons between the nucleus and the outer electron doesn't increase, only the number of electrons on the outer shell increases as you cross each group when going across a period

Why is there no increase in shielding across a period?