Question 1
a) What is meant by the term relative atomic mass? (2 marks)
b) State the number of protons, neutrons and electrons in an ion of chlorine. (3 marks)
c) A sample of bromine contains equal numbers of 79Br and 81Br. State the relative atomic mass of this sample of bromine. (1 mark)
d) Using sodium chloride and ammonia as examples, name the type of bonding in each compound and explain how the physical properties of the compounds differ because of the difference in bonding. (4 marks)
Answers
a) The average mass of an element relative to 1/12 of carbon-12.
b) 17 protons, 20 neutrons, and 18 electrons.
c) 80.
d) Sodium Chloride forms ionic bonds. This gives rise to high melting point because of the high electrostatic forces of attraction between the ions. Ammonia forms covalent bonds and simple molecules. Ammonia has low boiling and melting points because of the weak intermolecular forces between molecules.
Question 2
An atom of element Z has two more protons and two more neutrons than an atom of 168O.
a) Give the symbol, including mass number and atomic number of element Z. (2 marks)
b) Complete the electron configurations for the oxygen atom, O, and the oxide ion, O-2. (2 marks)
O 1s2
O-2 1s2
c) State the block of the Periodic Table in which oxygen is placed and explain your answer. (2 marks)
Answers
a) 2010Ne
b) O 1s22s22p4
O-2 1s22s22p6
c) The p-block. Highest or outermost electron is in the p shell/orbital.
