periodicity exam questions

Question 1

which element is classed as a d block element?
Antimony
Molybdenum
Strontium
Uranium

Answer 1

B - molybdenum

Question 2

Which element in period 3 has the highest melting point?
Aluminium
Silicon
Sodium
Sulfur

Answer 2

B silicon

Question 3

Which ion has the largest radius
F -
Mg2+
Na+
O2-

Answer 3

D - O2-

Question 4

Which element has a first ionisation energy lower than that of sulfur
Chlorine
Oxygen
Phosphorus
Selenium

Answer 4

D - Selenium

Question 5

When a piece of sodium is added to 200cm3 of water in a large beaker a vigorous reaction occurs. The temperature of the water increases by 25°C
Give an equation, including state symbols, for the reaction of sodium with water.
Suggest why it is dangerous to react a similar piece of sodium with 10cm3 of water in a boiling tube (2 marks)

Answer 5

M1: 2Na + 2H2O — 2NaOH +H2
M2: temperature will go up

Question 6

Give an equation for the reaction of phosphorus oxide with water
Suggest a pH for the solution formed

Answer 6

P4O10 + 6H2O — 4H3PO4
pH = -1

Question 7

Explain in terms of crystal structure and bonding why silicon (IV) oxide has a higher melting point than phosphorus oxide (4 marks)

Answer 7

M1: SiO2 is a macromolecular
M2: strong covalent bonds between atoms
M3: P4O10 is molecular
M4: weak van der waals between molecules

Question 8

An element in period 3 forms an oxide that is insoluble in water.
This oxide reacts with sulfuric acid and with potassium hydroxide
Give the formula of this oxide
Give an equation for the reaction of this oxide with sulfuric acid (2 marks)

Answer 8

Al2O3
Al2O3 + H2SO4 — Al2(SO4)3 +3H20