Summary AQA A level chemistry periodicity full revision notes

Periodcty
8. PERIODIC TABLE 2 TRENDS N PERI0D 3


Trends across peiod 3
MELTING
Pt Na, Ma ond Al have qiant metallic
X structures with strong metollie bonds
SI has a giant covalent structure
X
P,s, are simple molecules wth onl
X
X Van der Waals forces
Na Ma Al Si P Ar
Ar is monatom and hard to polans

AL has a higher melting pont than Na and Maq because t has the
strongest metall1e bonds due to highêr charge On ions and more deloul ised
electrons so theres a stronger electrostatie forces of attracton
hiqher than Pand Cl as the molecule is the largest larger
number of electrons ’ strongest Van der Waal

Properties
Atom1c rad1us decreases across a period
1ncreased nuclear charge ,no addit1onal shield1ng means electrons are
pulled loser to the nucleus
Ist ionisat1on enerqy increases auoss a penod
-




increased nuclear charqe, Similar shield1ng decre os ed atom1e rodius
means it's more ditficult to remove an electron

Exceptions
mol to 1E trend
kJ Between group 2 and 3- AL loses a 3p
/ electron, not a 3s electron sot takes le
IE
Ist
energy t0 (emove
Between group 5 and 6 S has a pair o
electrons n a 3p grbital which fepel an
Na Ma Al Si PS C Ar So are easier to remove