Unit 1 - Periodicity

Question 1

What does the number of protons in an atom determine?

Answer 1

Atomic number

Question 2

Does mp and bp increase or decrease down a group?

Answer 2

decreases

Question 3

why does mp and bp decrease down a group?

Answer 3

the forces of attraction are getting weaker, as a result of an increased screenig effect from the outer electron shells, that decreases electrostatic attractions between the nucleus and the decocalised electrons.

Question 4

does covalent radius increase or decrease down a group

Answer 4

increases

Question 5

why does covalent radius increase down a group

Answer 5

because of increasing outer electron shells.

Question 6

why does covalent radius decrease across a period

Answer 6

because there is a increasing nuclear charge from the increasing numbers of protons, which holds the electrons more closely together decreasing covalent radius

Question 7

covalent radius

Answer 7

half the distance between the nuclei of two bonded identical atoms

Question 8

Electronegativity

Answer 8

measure of the attraction which an atom has for the electrons in the bond.

Question 9

Explain the trends in ionisation energy on the periodic table

Answer 9

Across a period, the ionisation energy tends to increase as the nuclear charge increases.

Down a group the ionisation energy decreases as there are more shells, which means there is an increased screening effect due to the inner electrons

Question 10

First ionisation energy

Answer 10

the energy required to remove one mole of electrons from one mole of gaseous atoms.

Question 11

Second ionisation energy

Answer 11

the energy required to remove the 2nd mole of electrons.