A Level Chemistry Stuff for personal practice purposes and happiness.
Key points of the Vatican II Council
Full description
Full description
CHemistry Notes on Group II ELements
chemistry thermodynamics
solutions
Deskripsi lengkap
US
Descripción: Historiografía sobre la historia clásica de la arquitectura.
Full description
Full description
ease
Descripción: Grammar summary for ISE II. A selection of the grammar of ISE III with clear explanations
Meridian Junior College
Summary of Periodic Table - Chemical Periodicity
Physical Properties of Period 3 Element Period 3 element Atomic No. Atomic Radius Graph 1 Ionic Radius Graph 2 Melting pt
Na 11
Mg 12
Al 13
Formation of Cations Ionic Radius ↓ from Na+ to Si4+ as nuclear charge ↑ (each ion : Na+, Mg2+, Al3+, Si4+ have 10 e-) High m.p. due to giant metallic structure. There is strong metallic bonding. m.p. ↑ from Na to Al due to increasing metallic bond strength as no. of valence e- contributed per atom into sea of delocalised electrons ↑
Across the period, nuclear charge ↑ & negligible ↑ in shielding effect, effective nuclear charge ↑ atomic radius ↓
Graph 3
Electrical conductivity Graph 4 First I.E
Si 14
Highest m.p. due to macromolecular structure. Numerous covalent bonds between Si atoms arranged tetrahedrally in a 3Dimensional structure. Low electrical conductivity as Si is a metalloid
High electricial conductivity, ↑ from Na to Al as no. of valence e- contributed per atom into sea of delocalised electrons ↑ Generally 1st I.E. ↑ across period as nuclear chare g↑ and negligible increase in shielding effect, effective nuclear charge ↑ more energy required to remove the valence electron
Formation of Anions Ionic Radius ↓ from P3- to Cl- as nuclear charge ↑ (each ion : P3- , S2-, Cl- have 18 e-) Low m.p. due to simple molecular structure. Weak van der waals forces between molecules. M.p of S8 > P4 > Cl2 > Ar due to decrease in size of electron cloud as no. of electrons decreases.
Non-conductor of electricity due to absence of delocalised electrons or mobile ions
Lower 1st I.E of Al than Mg as the 3p e- in Al is at further away from the nucleus compared to 3s e- being removed in Mg; Lower 1st I.E of S than P as a paired 3p e- in S is removed which experiences inter-electron repulsion compared to an unpaired 3p ein P. ↑ across period as nuclear charge ↑ and negligible increase in shielding effect, Effective. nuclear charge ↑ across period.
1
Summary of Trends exhibited by Elements across Period 3 Atomic radius / nm
Properties of Period 3 Oxides Period 3 oxide Oxidation No.
Na2O
MgO
Al2O3
SiO2
P4O6, P4O10
SO2, SO3
+1
+2
+3
+4
+3, +5
+4, +6
Oxidation no. of oxides ↑ across period as no. of valence e- available for bond formation ↑
Structure Nature of Oxide Reaction with water*
Giant Ionic Lattice Structure Ionic & basic Forms NaOH with water (pH ≈ 13)
Forms Mg(OH)2 with boiling water (pH ≈ 9)
Giant molecular Structure
Ionic & amphoteric
Simple molecular Structure Covalent & acidic
No reaction (pH = 7)
Form H3PO3, H3PO4 with water
Form H2SO3, H2SO4 with water
(pH ≈ 2)
(pH ≈ 2)
Na2O(s) + H2O(l) MgO (s) + H2O(l) Al2O3 does not dissolve in water because of P4O6(s) + 6H2O(l) 4H3PO3(aq) → 2NaOH(aq) Mg2+ (aq) + its extremely high lattice energy 2OH (aq)
SiO2
- Large amounts of energy are required to break the numerous strong covalent bonds, solvation cannot occur.
Reaction with acid*
Form salt and water Na2O(s) + 2HCl(aq) 2NaCl(aq) + H2O(l) MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l)
Reaction with alkali*
No reaction
Forms Al3+ (aq)
SO3(g) + H2O(l) H2SO4(aq)
No reaction
Al2O3(s) + 6HCl(aq) 2AlCl3(aq) + 3 H2O(l) White ppt dissolves in excess NaOH to form colorless complex, Al(OH)4 (aq) Al2O3(s) + 3H2O(l) + 2NaOH(aq) 2NaAl(OH)4(aq)
