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Laws of periodicityDescription complète
Natural Law applied to horse racing betting using occult Numerology and Astrology
Natural Law applied to horse racing betting using occult Numerology and Astrology
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chemistry thermodynamics
Laws of periodicity
Deskripsi lengkap
Descripción: Historiografía sobre la historia clásica de la arquitectura.
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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)
