Periodic Table 07

Question 1

variation in OXIDATION NUMBER of period 3 oxides and chlorides

Answer 1

increases across the period

Question 2

variation in MELTING POINTS of period 3 oxides

Answer 2

decreases across the period

Question 3

what are basic, amphoteric and acidic oxides?

Answer 3

metals that form ionic bonds, aluminium(only amphoteric oxide in period 3), and non metals that form covalent bonds

Question 4

solubility of basic, amphoteric and acidic oxides and hydroxides

Answer 4

Basic Oxides:
Na: vigorous reaction, dissolves completely in water. forms a strongly alkaline solution
Mg: slow reaction and limited solubility
both dissolve in acids

hydroxides:
dissolves in water

Amphoteric Oxides: no reaction in water
dissolves in acids
dissolves in EXCESS base

hydroxides:
insoluble in water

dissolves readily in acids

dissolves in EXCESS strong base

Acidic Oxides:
does not react or dissolve in water

requires in only HOT AND CONCENTRATED acids in order to react

Question 5

Chlorides: structure and bonding

Answer 5

NaCl and MgCl: giant ionic lattice structure

AlCl3 and PCl, SiCl4: Simple (discrete) covalent molecules

Question 6

Melting points of chlorides

Answer 6

Na, Mg, Al and P are solids while Si liquid

Question 7

Group one reducing power

Answer 7

increases down group 1

Question 8

group 17 volatility

Answer 8

decreases down group 17, from Cl2 to I2

Question 9

group 17 mp/bp

Answer 9

Increases down the group due to the stronger dispersion forces down the group

Question 10

group 17 reducing power

Answer 10

oxidising power of the halogens decreases down the group

Question 11

Thermal stability of group 17 hydrides

Answer 11

thermal stability depends on the strength of the H-X bond
Down the group, from F to I, the bond length increases and hence, the bond strength decreases. Less energy is needed to break the H-X bond, and the thermal stability of halides decreases down the group

Question 12

Reaction of chlorides with water

Answer 12

NaCl: dissolves in water to form a colorless solution with neutral pH

MgCl2: dissolves in water to form slightly acidic pH

AlCl3:
reaction with limited amounts of water:
steamy white fumes of HCl are formed, and a white solid remains, insol in water.

reaction with large amounts of water:
AlCl3 dissolves to form a colourless solution with acidic pH

remainder of chlorides undergo complete hydrolysis and form strongly acidic solutions.

SiCl4/PCl5: violent reaction producing fumes of HCl gas.