periodicity

Question 1

what is the first ionisation energy?

Answer 1

the energy needed to remove one mole of electrons from one mole of atoms in their gaseous state to form one mole of 1+ ions (also in their gaseous state)

Question 2

what is the second ionisation energy?

Answer 2

the energy needed to remove one mole of electrons from one mole of 1+ ions in their gaseous state to form one mole of 2+ ions (also in their gaseous sate)

Question 3

what are the three factor that effect ionisation energy?

Answer 3

• atomic radius (lower atomic radius, greater ionisation energy as the attraction of the nucleus to the electrons is greater)
• charge on the nucleus (the greater the number of electrons, the greater the ionisation energy as the attraction of the nucleus and electrons are greater)
• sheilding (sheilding reduces the attraction between the outer electrons and the nucleus as the electrons in the outer shell are repelled by electrons in inner shells. Therefore the greater the shielding, the lower the ionisation energy)

Question 4

why does ionisation energy gradually increase at first?

Answer 4

each time an electron is removed, the remaining electrons on the outer shell are pulled closer to the nucleus meaning there is a greater attraction.

Question 5

why does ionisation energy have a massive increase?

Answer 5

when the last outer electron is removed, there is less shielding so there is a greater attraction

Question 6

why does B have a lower ionisation energy than Be?

Answer 6

B is now in the 2p subshell, not 2s. The 2p subshell has a higher energy than the 2s subshell. This means it takes less energy to remove the outer electron

Question 7

why does O have a lower ionisation than N?

Answer 7

In N, each electron is in a seperate 2p orbital. But in O, one of the orbitals contains a pair of electrons. These electrons repel each other, therefore less energy is needed to remove the outer electron.

Question 8

describe the relative energies of 2s orbitals and each of the three 2p orbitals (2marks)

Answer 8

the 3 p orbitals have equal energies and p-orbitals have greater energy than s-orbitals

Question 9

what is periodicity?

Answer 9

repeating pattern of similar properties in elements occupying similar positions on the periodic table