STRUCTURE OF THE ATOM
AND THE PERIODIC TABLE
Review Questions
Complete the following word equations. Write balanced chemical equations for the reactions listed below.
(a) Sodium hydroxide + dilute hydrochloric acid
(b) Zinc oxide + dilute sulphuric acid
(c) Zinc metal + dilute nitric acid
(d) Calcium carbonate + dilute sulphuric acid
(e) Calcium hydrogen + carbon (IV) oxide
(f) Sodium + water
1. 2006 Q 12 P1
The table below shows the relative atomic masses and the percentage abundance of the
isotopes L1 of element L2.
Relative atomic mass % abundance
L1 62.93 69.09
L2 64.93 30.91
Calculate the relative atomic mass of element L. (3 marks)
2. 2007 Q 26 P1
The table below shows the number of valence electrons of the element P, Q and R.
Element P Q R
Number of valence electrons 3 5 2
(a) Explain why P and R would not be expected to form a compound. (1 mark)
(b) Write an equation to show the effect of heat on the carbonate of R. (1 mark)
(c) Write the formula for the most stable ion or Q. (1 mark)
3. 2008 Q 7 P1
(a) What are isotopes? (1 mark)
18
(b) Determine the number of neutrons in 8O (2 marks)
4. 2009 Q6 P1
An isotope of element E has 34 neutrons and its mass number is 64. E forms a cation with
28 electrons. Write the formula of the cation indicating the mass and atomic numbers.
(1 mark)
5. 2010 Q2 P1
(a) What is meant by the terms: (2 marks)
(i) Element;
(ii) Atomic number.
(b) The formula for a chloride of titanium is TiCl3. What is the formula of its sulphate?
(1
mark)
6. 2011 Q 5a, b (i-iii) PP2
(a) Other than their location in the atom, name two other differences between an electron
and a proton. (2 marks)
-2- PHYSICAL CHEMISTRY
(b) The table below gives the number of electrons, protons and neutrons in particles A, B,
C, D, E, F and G
Particle Protons Electrons Neutrons
A 6 6 6
B 10 10 12
C 12 10 12
D 6 6 8
E 13 10 14
F 17 17 18
G 8 10 8
(i) Which particle is likely to be a halogen? (1 mark)
(ii) What is the mass number of E? (1 mark)
(iii) Write the formula of the compound formed when E combines with G? (1mark)
7. 2011 Q 24
The table below gives the number of electrons, protons and neutrons in Substances X, Y
and Z.
Substance Electrons Protons Neutrons
X 10 10 10
Y 10 8 10
Z 8 8 8
(a) Which letter represents an ion? (1 mark)
(b) Which of the substances are isotopes? Give a reason. (2 marks)
8. 2013 Q29 P1
A sample of hydrogen gas was found to be a mixture of two isotopes 12 H and H. Determine
the relative molecular masses of the molecules 11 formed, when each of these isotopes is
burnt in oxygen. (O =16.0) (2
marks)
9. 2014 Q18 P1
Use the part of the periodic table given below to answer the questions that follow (Letters
are not the actual symbols of the elements
(a) Identify the element that forms giant covalent structures. (1 mark)
(b) Identify one element that does not form compounds. (1 mark)
(c) Write the formula for the nitride of M. (1 mark)
10. 2014 Q29 P1
(a) What is meant by the term radical?
(b) The table below contains atoms that form common radicals. Complete the table to show
radicals formed from various atoms. (2
marks)
Element N S
H NH4+
STRUCTURE OF THE ATOM - 3 -
11. 2015 Q10 P1
The atomic number of an element, T is 15.
(a) Write the electronic configuration of the ion T (1 mark)
(b) Write the formula of an oxide of T. (1 mark)
12. 2015 Q14 P1
The table below shows behaviour of metals R, X, Y and Z. Study it and
answer the questions that follow:
Metal Appearance on Reaction in water Reaction with dilute
exposure to air hydrochloric acid
R slowly tarnishes Slow Vigorous
X Slowly turns white Vigorous Violent
Y No change Does not react Does not react
Z No change No reaction Reacts moderately
(a) Arrange the metals in the order of reactivity starting with the most reactive (2 marks)
(b) Name a metal which is likely to be (1 mark)
(i) X (ii) Y
13. 2015 Q7a P2
Naturally occurring magnesium consists of three isotopes. 78.6% 24Mg; 10% 25Mg and 26Mg.
Calculate to one decimal place, the relative atomic mass of magnesium. (2 marks)
14. 2017 Q11 P1
An oxide of element K has the formula K2O5.
(a) Determine the oxidation number of K. (1 mark)
(b) To which group of the periodic table does K belong? (1 mark)
15. 2018 P1 Q17.
Figure 5 represents a grid that is part of the periodic table. Study it and answer the
questions that follow. The letters are not the actual symbols of the elements.
(a) Write the electron arrangement of element C. (1 mark)
(b) On the grid provided, show with a tick (✓) the position of element D whose atomic
number is 18.
(1 mark)
(c) Element E is more reactive than A. Explain. (1 mark)
16. 2019 Q1 P1
An atom of element A has mass number 39 and 19 protons.
(a) Write the electron arrangements of the atom. (1 mark)
-4- PHYSICAL CHEMISTRY
(b) State the period and group to which element A belongs
Group ........................................ (½ mark)
Period ......................................... (½ mark)
(c) State whether the element is a metal or a non-metal. (1 mark)
