Question

(b) group i elements have lower melting - points than transition elements. describe one other difference in the physical properties of group i elements and transition elements.

(c) group vii elements are known as the halogens. astatine is below iodine in group vii. predict the physical state of astatine at room temperature and pressure.

(d) some group vii elements react with aqueous solutions containing halide ions. when aqueous chlorine is added to aqueous potassium bromide a reaction occurs. the ionic half - equations for the reaction are shown.
cl_2(aq)+2e^-
ightarrow2cl^-(aq)
2br^-(aq)
ightarrow br_2(aq)+2e^-
(i) describe the colour change of the solution.
original colour of potassium bromide solution
final colour of reaction mixture

1. this question is about group iv elements and their compounds.

(a) the changes of state of lead are shown.
\text{solid lead}xrightarrow{\text{melting}}\text{liquid lead}xrightarrow{b}\text{lead gas}xleftarrow{\text{condensing}}
name the changes of state represented by a and b.
a
b

(b) use the kinetic particle model to describe the differences between liquid lead and lead gas in terms of:

• the separation of the particles

Explanation:

(b) Group I elements are softer and more reactive than transition elements.
(c) Astatine is likely to be a solid at room - temperature and pressure as the physical state of Group VII elements changes from gas to liquid to solid down the group.
(d)(i) The original colour of potassium bromide solution is colourless. When aqueous chlorine is added, it oxidizes bromide ions to bromine. Bromine in solution gives an orange - brown colour, so the final colour of the reaction mixture is orange - brown.
7.(a) A is freezing (or solidification), B is vaporization (or boiling).
(b) In liquid lead, the particles are close together with some freedom of movement. In lead gas, the particles are much more widely separated and move freely in all directions.

Answer:

(b) Group I elements are softer.
(c) Solid
(d)(i) original colour of potassium bromide solution: Colourless; final colour of reaction mixture: Orange - brown
7.(a) A: Freezing; B: Vaporization
(b) In liquid lead, particles are close; in lead gas, particles are widely separated.