KA1- Periodicity

Question 1

Melting and boiling points across period

Answer 1

As you go across, the melting point decreases
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 group 1

Answer 2

Decreases

Question 3

Melting/ boiling points down group 7

Answer 3

Increases

Question 4

Melting/ boiling points down group 8/0

Answer 4

Increases

Question 5

Higher melting and boiling points

Answer 5

Indicates an increase in the intermolecular forces between atoms

Question 6

Periodicity

Answer 6

The occurrence of patterns in the periodic table

Question 7

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

Answer 7

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 8

Atomic size/ covalent radius across a period

Answer 8

Each element has the same number of energy levels so additional electrons are being added into the same energy level
The number of protons in the nucleus increases so there is a increasing nuclear pull on the outer electrons from the extra positive charges
This results in the electron shells being pulled closer in towards the nucleus
Therefore, atomic size decreases across a period

Question 9

Atomic size down a group

Answer 9

The number of occupied electron energy levels are increasing and they shield the outer electron from the nuclear pull
Therefore the atomic size increases

Question 10

Ionisation energy (explain, page)

Answer 10

Explained in terms of atomic size, nuclear charge and screening effect (due to inner shell electrons)
Page 12

Question 11

Firs ionisation energy

Answer 11

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 12

First ionisation energy going down a group

Answer 12

The extra electron shells shield the outer electrons from the nuclear pull so they are increasingly distant from it
The outer electron becomes easier to remove
1st ionisation energy decreases

Question 13

First ionisation energy across a period

Answer 13

The number of protons in the nucleus increases, so their is an increasing nuclear pull on the outer electrons which are held in the same shell, so are held increasingly tightly
The outer electron becomes more difficult to remove
1st ionisation energy increases

Question 14

Second ionisation energy

Answer 14

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

Question 15

Third ionisation energy

Answer 15

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

Question 16

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

Answer 16

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

Question 17

Electronegativity across a period

Answer 17

Across a peirod, atoms become smaller in size, so the electrons are closer to the nucleus
The electron attraction to the nucleus is therefore increased due to the close proximity
Therefore, the Electronegativity increases across a period

Question 18

Electronegativity downs group

Answer 18

Decreases down a group because, as another energy level is added there is an increase in the shielding effect
The outermost electrons are further away and shielded from the pull of the nucleus