KA1- Periodicity

Question 1

Melting and boiling points across period

Answer 1

Decrease going across a period
Metals have higher melting points in comparison to non-metals- exception carbon due to bonding, it sublimes- goes from a solid state to gas, without passing through the liquid state

Question 2

Melting/ boiling point going down groups

Answer 2

Decreases across group 1
Increase across group 7 and 8

Question 3

Higher melting and boiling points

Answer 3

Indicates an increase in the intermolecular forces between atoms

Question 4

Atomic size/ covalent radius (definition, explained, across/down, page)

Answer 4

Half the distance between the 2 nuclei in a covalent bond
Explained in terms of nuclear charge and number of occupied shells
Decreases across period
Increases down group
Page 7

Question 5

Atomic size/ covalent radius across a period

Answer 5

Electrons are being added into the same energy level. The number of protons increase so there’s an increasing nuclear pull on the outer electrons, the shells are pulled in towards the nuclear pull and therefore decreases

Question 6

Atomic size down a group

Answer 6

The number of occupied electron energy levels increase which shield the outer electrons from the nuclear pull so atomic size increases

Question 7

Ionisation energy (explain, page)

Answer 7

Atomic size, nuclear charge and screening effect (due to inner shell electrons)
Page 12

Question 8

First ionisation energy

Answer 8

The energy required to remove one mole of electros from one mole of gaseous atoms
Endothermic process- energy required to remove an electron
Eg Mg(g)—> Mg+(g) + e-
Decreases down a group
Increase across a period

Question 9

First ionisation energy going down a group

Answer 9

Increasing energy levels means the outer electrons are increasingly further and shielded from the nuclear pull making it easier to remove

Question 10

First ionisation energy across a period

Answer 10

The number of protons increase so there is an increasing nuclear pull on the outer electrons which are held in the same shell so are held increasingly tightly making it more difficult to remove so increases

Question 11

Second ionisation energy

Answer 11

The enegry required to remove a second mole of electrons from one mole of gaseous atoms
Eg Mg+(g) — > Mg2+(g) + e-

Question 12

Third ionisation energy

Answer 12

The energy required to remove a third mole of electrons from one mole of gaseous atoms
Eg Mg2+(g) —> Mg3+(g) + e-

Question 13

Electronegativity (definition, large value, explain, page, across/down)

Answer 13

A measure of the attraction an atom involved in a bond has for the electrons of the bond
Large electronegativity value indicates a large attraction for the shared electrons
Covalent radius, nuclear charge and screening effect (due to inner shell electons)
Page 12
Increases across period
Decreases down group

Question 14

Electronegativity across a period

Answer 14

Atoms become smaller so the electron attraction to the nucleus increases due to the close prolixity and therefore increases

Question 15

Electronegativity downs group

Answer 15

Increase in shielding effect means outer electrons are further from the nucleus so decreases