Periodicity 2.1

Question 1

what is periodicity

Answer 1

the repeating pattern of physical or chemical properties going across the period

Question 2

what’s the trend in atomic radius

Answer 2

Atomic radii decreases from left to right across a period because the increased number of protons create more positive charge attraction for electrons which are in the same shell with similar shielding

Question 3

what’s the trend in 1st ionisation energy

Answer 3

Increases
-Increasing number of protons as the electrons are being added to the same shell
- slight drop between Mg and Al .
Mg has its outer electron in the 3s sub shell whereas Al is starting to fill the 3p subshell.
Al’s electron is slightly easier to remove because the 3p electrons are higher in energy
- There is a small drop between phosphorus and sulfur
Sulfur outer electron is being paired up with another electron in the same 3p orbital .
There’s a slight repulsion between the two negatively charged electrons which makes the second electron easier to remove

Question 4

what’s the trend in melting and boiling points for Na , Mg and Al

Answer 4

Strong bonding - gets stronger the more electrons there are in the outer shell that are released to the sea of electrons .
A smaller sized ion with a greater positive charge also makes the bonding stronger
Higher energy is needed to break bonds

Question 5

what’s the trend in melting and boiling point of Si

Answer 5

Si is macromolecular
many strong covalent bonds between atoms , high energy needed to break covalent bonds - very high mp and bp

Question 6

what’s the trend in melting point and boiling point of Cl2 , S8 and P4

Answer 6

they’re simple molecular
weak van der waals between molecules , so little energy is needed to break them so they have low melting and boiling points

Question 7

why does S8 have a higher mp than P4

Answer 7

it has more electrons so has stronger van de waals forces between molecules

Question 8

what’s the trend in mp and bp in Ar

Answer 8

Ar is monoatomic so weak van de waals between atoms

Question 9

what’s the element in period 3 which has the highest second ionisation energy

Answer 9

Sodium

Question 10

what’s the equation to show the highest second ionisation energy of the element

Answer 10

Na + (g) => Na2+ (g) + e-