Electron Arrangement + Ionisation Energies

Question 1

What is the energy called that is used to remove electrons from atoms?

Answer 1

This energy is called ionisation energy

Question 2

What is ionisation energy?

Answer 2

This is the energy required to remove a mole of electrons from a mole of atoms in the gaseous state and is measured in kJmol-1

Question 3

What is ionisation energy measured in?

Answer 3

Ionisation energy is measured in kJmol-1

Question 4

How are electrons removed one by one?

Answer 4

The first electron is removed and needs the least amount of ionisation energy because it is being removed from a neutral atom.

The second electron is removed and needs more energy because it is being removed from a +1 ion

The third electron is removed and needs even more energy because it is being removed from a +2 ion.

The fourth electron needs an even high amount of energy and this continues in other electrons

Question 5

What is the trend in ionisation energies across a period in the periodic table?

Answer 5

Ionisation energies generally increase across a period because the nuclear charge is increasing and makes it more difficult to remove an electron

Question 6

What are the first ionisation energies of the elements in Period 3?

Answer 6

Sodium (Na) = 496kJmol-1

Magnesium (Mg) = 738kJmol-1

Aluminium (Al) = 578kJmol-1

Silicon (Si) = 789kJmol-1

Phosphorous (P) = 1012kJmol-1

Sulfur (S) = 1000kJmol-1

Chlorine (Cl) = 1251kJmol-1

Argon (Ar) = 1521kJmol-1

Question 7

What is the removal of electrons one by one called?

Answer 7

The successive ionisation energies

Question 8

The increase is not regular from magnesium (1s2, 2s2, 2p6, 3s2,) to aluminium (1s2, 2s2, 2p6, 3s2, 3p1) is not regular. Why is this?

Answer 8

The ionisation energy goes down from magnesium to aluminium, despite the increase in nuclear charge. This is because the outer electron in aluminium is in a 3p orbital which is of a slightly higher energy level than the 3s orbital. Therefore it needs less energy to remove

Question 9

There is a small drop between phosphorous (1s2, 2p2, 2p6, 3s2, 3p3) and sulfur (1s2, 2s2, 2p6, 3s2, 3p4). Why is this?

Answer 9

In phosphorous, each of the 3p orbitals contain just one electron, while in sulfur, one of the 3p orbitals must contain two electrons. The repulsion between these paired electrons makes removal easier, despite increased nuclear change

Question 10

What is the trend in ionisation energies down a group in the Periodic table?

Answer 10

Generally there is a decrease in first ionisation energies going down groups. This is because the outer electrons are in a main level that gets further from the nucleus in each case

Question 11

What is the general trend as you go across a period on a Periodic table?

Answer 11

As you go across a period the ionising energy required increases. The electron being removed is more strongly attracted by the nucleus because of the extra proton, even though distance and shielding has remained the same

Question 12

Why are the electrons on the outermost shell lost first?

Answer 12

The electrons on the outermost shell are lost first because they have the smallest amount of nuclear attraction therefore needing the smallest ionisation energy

Question 13

What is the full order of writing electron configurations?

Answer 13

1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p6, 4d10, 4f14

Question 14

What is the trend in boiling points of the noble gases?

Answer 14

As you go down the group, there are more electrons. As the temporary dipole is caused by electron distortion, the more electrons, the greater distortion and the stronger the van der Waals forces