WJEC Chemistry for AS Level Student Book: 2nd Edition (Draft)

WJEC Chemistry for AS Level

Test yourself 1. (a) Complete the table below, which relates to the particles contained in an atom.

[3]

Particle

Relative mass

Relative charge

Proton

1

(b) An element, X, has an atomic number of 47 and forms an ion X + . State the number of protons and electrons in this ion .

[1]

(c) The symbols 23

63 29 Cu and

65 29 Cu and, represent sodium atoms and

11 Na,

copper atoms respectively. Use these symbols to explain the meaning of the terms: (i) Mass number

[2]

(ii) Isotope [2] (d) Name the species which, on gaining an electron, has a full set of 2p orbitals. [1] (e) Show the electronic configuration of a titanium atom. [1] 2. (a) One of the unstable isotopes of platinum, 199 Pt, decays by β -emission. (i) Write an equation to show this decay. [1] (ii) State what happens in the nucleus of an atom when a β -particle forms. [1] (iii) 10.0 mg of 199 Pt decays to 1.25 mg in one hour and 33 minutes. Calculate the half-life of this isotope. [1] (b) 23 Mg decays by positron emission which is another type of β -decay. Give the mass number and symbol of the species produced when 1 atom of 23 Mg decays. [1] (c) Describe why radioactivity is dangerous to living cells. Explain which type of radiation causes most damage to cells. [4] 3. (a) The first four ionisation energies for an element, X, are shown in the table below.

Ionisation energy / kJ mol –1

1st DRAFT 2nd 3rd 4th 1000 2260 3390 4540 State what you can deduce about the group to which the element belongs. Explain your answer. [2] (b) Nitrogen has a first ionisation energy of 1400 kJ mol –1 . State and explain how you would expect the first ionisation energy of nitrogen to compare with the first ionisation energy of: (i) Carbon [2] (ii) Oxygen [2] (iii) Phosphorus [2] 30