Answers to end-of-chapter questions
Chapter 2
a atoms of the same element with different
nucleon numbers / mass numbers / different
numbers of neutrons
b i protons = 5
ii neutrons = 6
iii electrons = 5
1
1
1836
charge = −1
ii mass = 1
charge = zero
iii mass = 1
charge = +1
c i mass =
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
Total = 10
[1]
Zr
ii 51
[1]
b 70
[1]
c i It is deflected / bends away from the
anode, or towards cathode, or downwards. [1]
Proton has positive charge since like
charges repel / or opposite charges attract. [1]
ii no deflection / go straight through
[1]
neutrons have no charge
[1]
Total = 7
2
a i
91
40
positively charged nucleus;
containing protons and neutrons;
electrons outside the nucleus in energy levels;
protons are positively charged with relative
mass of 1;
neutrons are neutral with relative charge of
zero and relative mass of 1;
electrons are negative with relative charge
3 a
of −1 and relative mass of
[allow
[1]
[1]
[1]
b atomic number = number of protons
(in the nucleus);
[1]
nucleon number
= number of protons + number of neutrons
[1]
c Mg = 12 protons, 12 electrons, 12 neutrons
[1]
Al = 13 protons, 13 electrons, 14 neutrons
[1]
d number of positively charged protons
= number of negatively charged electrons
[1]
e it would not be oxygen / it would be another
element / oxygen can only have 8 protons
[1]
f The mass of an electron is negligible.
[1]
Total = 13
a atoms of the same element with different
nucleon numbers / mass numbers / different
numbers of neutrons
[1]
b i both have 92 protons;
[1]
both have 92 electrons
[1]
ii uranium-235 has 143 neutrons;
[1]
uranium-238 has 146 neutrons
[1]
c 90
[1]
Total = 6
4
5 a number of protons = 17 and 17
number of electrons = 17 and 17
number of neutrons in chlorine-35 = 18
and in chlorine-37 = 20
b the chlorine-35 isotope is more abundant;
the weighted average is nearer 35 than 37
c i it has more protons than electrons
ii it has 17 protons and 18 electrons / it has 1
more electron than protons
[1]
[1]
[1]
[1]
[1]
[1]
[2]
[it has more electrons than protons for 1 mark]
Total = 8
[1]
[1]
1
1836
1
or negligible]
2000
AS and A Level Chemistry © Cambridge University Press
[1]
Answers to end-of-chapter questions: Chapter 2
1