Periodic Table Flashcards
Atomic radius trend across period 3
Atomic radius decreases across period
Describe ionic radii trend across period
Anions larger than cations
(P³-, S²-, Cl-)
Anions have 1 more shell of e- than cations, valence e- in anions have greater shielding effect, less strongly attracted to the nucleus.
Describe 1st ionisation energy across period
General Trend: Increase
Proton increase, nuclear charge increase
Same shell, shielding effect relatively constant
ENC increases, stronger eFOA
**Why Mg IE> Al
3p valence in Al higher energy, less energy required to remove
**Why P IE > S
Inter electron repulsion in 3p orbital of S atom, less energy req.
Describe EN across period
EN increases
proton increase Nuclear charge increase
Same period shielding effect remains relatively constant
ENC increase stronger eFOA
Melting pt & electrical conductivity
Chemical properties across period 3
Oxidation numbers +ve, less EN than O2 or Cl2
P & S central atom has expanded octet -> vacant & energetically accessible 3d orbitals
Properties of period 3 oxides
mp MgO > Al2O3 > Na2O
strong eFOA betw oppositely charged ions, Mg2+ higher lattice energy than Na+
Al2O3 mp< MgO due to Al3+ high charge density, polarises O2-, covalent character, weakens ionic bond strength
SiO2 high, lower than Al2O3
numerous strong covalent bonds betw Si & O atoms
P & S oxides SMS, idid, P4O10 > SO3, larger e- cloud size, greater extent of distortion
Rxn period 3 oxides w H²O
Na²O + H²O ->2NaOH pH 13
Dissolves in water
MgO + H²O <=> Mg(OH)
Dissolves sparingly in water pH 9
Al²O³ insoluble in water due to high Lattice energy pH 7
SiO² insoluble in water due to strong extensive covalent bonds pH 7
P⁴O¹⁰ + 6H²O -> 4H³PO⁴ pH 3
SO³ + H²O -> H²SO⁴ pH 1
Properties of period 3 chlorides
Rxn of period 3 chlorides
Atomic & Ionic radii down grp
1st IE & EN down grp
melting & boiling pt down grp
Chemical properties down grp 2
Grp 2 reducing power
Thermal stability grp2 carbonates
Grp 17 oxidising power
Thermal stability of grp 17 hydrides
