Metals

Question 1

why are metals malleable, have high melting and boiling points and are good conductors of electricity? (3 points)

Answer 1

1. they have layers of orderly arranged atoms that can slide over one another easily
2. they have strong forces of attractions between positive metal ions and “sea of elections”
3. they have mobile ions

Question 2

why are pure metals not widely used in the industry? (2 points)

Answer 2

pure metals are too soft as the layer of atoms slide over one another easily when a force is applied

Question 3

what is an alloy? (1 point)

Answer 3

it is a mixture of a metal and one or a few other elements

Question 4

why are alloys stronger/harder than most constituent metals? (3 points)

Answer 4

it is because atoms of elements added are of different sizes and the regular/orderly arrangement of atoms is disrupted. this leads to the layers not being able to slide over one another easily when a force is applied

Question 5

why are metals often used in the from of alloys? (4 points)

Answer 5

1. it makes the metal harder/stronger
2. it improves the appearance of the metals
3. to lower the melting point of the metal
4. makes the metal more resistant to corrosion

Question 6

state the reactivity series? (1 point)

Answer 6

K, Na, Ca, Mg Al, [C], Zn, Fe, Sn, Pb, [H], Cu, Ag, Au

Question 7

why do metals have different reactivity? (3 points)

Answer 7

metals tend to lose electrons to form cations (1) and the tendency to lose electrons is related to its reactivity (2). so, a more reactive metal has a higher tendency to lose electrons (3)

Question 8

what is a metal displacement reaction? (2 points)

Answer 8

a more reactive metal can displace a less reactive metal from its salt solution. a more reactive metal can also reduce the oxide of a less reactive metal

Question 9

what is reduction of metal oxides with carbon? (2 points)

Answer 9

it is when carbon removes oxygen from the oxides of metals that are not too high up in the reactivity series. for example, oxides of Zn, Fe, Pb and Cu can be reduced through heating with carbon

Question 10

what is reduction of metal oxides with hydrogen (2 points)

Answer 10

it is when hydrogen removes oxygen from metallic oxides, producing the metal and water. oxides of Pb and Cu can be reduced through heating with hydrogen gas

Question 11

describe thermal decomposition of metal carbonates.

Answer 11

most metals decompose upon strong heating to form metal oxides and carbon dioxide