Chapter 8 - Periodicity

Question 1

What are the 4 large blocks in the periodic table called, and how are they determined?

Answer 1

They are the S,P,D and F blocks and are determined by the proton number of the elements nucleus. in general, group one and 2 are S, non metals are P and transition metals are D, with lanthanides and actinides being F

Question 2

How does atomic radius change as you go across Period 3? Why?

Answer 2

Atomic radius decreases, because the shielding will stay the same (same number of shells) however the protons increase and therefore exert a greater pull on the electron clouds, therefore they are closer to the nucleus

Question 3

How does first ionisation energy change across Period 3? Why?

Answer 3

Na, very low, easy to lose electron as only one in shell 3, Mg harder as 3s2 - 3s1, Al lower than Mg becasue losing only electron in 3p shell. After this increases steadily until Sulfur where it is lower than Phosphorous, due to removing only upspin 3p electron, not too difficult. Continues steadily to end of period

Question 4

Explain the trend in MP and BP across Period 2.

Answer 4

It increases from Na to Al because they all have metallic bonding, however each successive element releases more electrons to make a more positive ion, so stronger attractive forces in lattice. It then increases again for silicon because it is macromolecular before dropping massively to Phosphorus - strongest bond present in the rest of period = VDW, P4, then increases MP to S8 but drops again to Cl2, Argon has very very low MP