periodicity

Question 1

what is common in all period 3 elements

Answer 1

they’re in the same energy level (3s and 3p), therefore there’s a similar amount of shielding

Question 2

what changes across period 3 elements (4)

Answer 2

number of protons increases
atomic radius decreases
there’s more attraction between valence electron and nucleus
therefore atom size decreases

Question 3

what is the first ionisation energy

Answer 3

energy needed to remove 1 mole of electrons from 1 mole of atoms in their gaseous state, to form 1 mole of +1 ions in their gaseous state
X(g)–>X+(g) + e-

Question 4

trend in first ionisation energy across period 3 elements

Answer 4

general increase
increase: Na-> Mg
decrease: Mg-> Al
increase: Al-> Si-> P
decrease: P-> S
increase: S->Cl->Ar

Question 5

why is there a dip from Mg->Al

Answer 5

-in Al, electron is removed from p orbital (elec config= [Ne] 3s2, 3p1)
-which is higher in energy/ shielded by 3s
-so its lost more easily

Question 6

why is there a dip from P->S

Answer 6

-in S, there are paired electrons in p orbital
-paired electrons repel
-it is easier to remove

Question 6

what type of bonding is in Na, Mg and Al
what is the trend in MP

Answer 6

-metallic
-across these elements: smaller ion, greater charge, more delocalised electrons increases MP

Question 6

what type of bonding is in Si
what is the trend in MP

Answer 6

-macromolecular/ giant covalent
-many strong covalent bonds need lots of energy to overcome

Question 6

what type of bonding is in P, S Cl
what is the trend in MP

Answer 6

-simple covalent (P4, S8, Cl2)
-van der waals forces between molecules increases as molecule gets bigger, so more energy needed to overcome
-out of these 3 elements: S8=highest MP, P4= 2nd highest, Cl2= lowest MP

Question 7

what type of bonding is in Ar

Answer 7

-monatomic
-lower MP than Cl due to weaker van der waals forces which don’t need much energy to overcome