3.2.1 Periodicity

Question 1

Define periodicity

Answer 1

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

Question 2

Trend of atomic radii across periods

Answer 2

Decrease

Question 3

explain the trend in atomic radii across periods

Answer 3

increased number of protons (nuclear charge)
stronger positive charge pulls electrons closer to the nucleus
similar shielding

Question 4

general trend in first ionisation energy across period 3

Answer 4

increases

Question 5

explain the general trend in first ionisation energy across period 3

Answer 5

increasing nuclear charge (number of protons)
decreasing atomic radii
similar shielding

Question 6

why is there a small drop in first ionisation energy between Mg and Al

Answer 6

Mg has its outer elctron in 3s sub shell wheras Al has its outer electron in the 3p sub shell
3p orbital is higher in energy meaning the electron in Al is less tightly held than in Mg, making it easier to remove

Question 7

why is there a small drop in first ionisation energy between P and S

Answer 7

in P each 3p electron is in a separate orbital
but in S one of the 3p orbitals now has a paired electron
repulsion between the paired electrons
weakening attraction to the nucleus
easier to remove an electron in sulfur

Question 8

what type of bonding is between Na, Mg and Al

Answer 8

metallic bonding

Question 9

what type of bonding is in Si

Answer 9

covalent bonds
(macromolecular structure)

Question 10

what is the trend in melting/boiling points in period 3 after Si

Answer 10

decreases

Question 11

explain the trend in melting/boiling points in period 3 after Si

Answer 11

non-metals, with a simple molecular structure
weak van der waals forces