Atomic Masses – Grade C Exam Question
Atoms are made up of three main particles called protons, neutrons and
electrons.
(a) Aluminium is in Group 3 of the periodic table and has an atomic
number of 13
The atomic number
is the same as the
number of protons
in an atom. In this
case the atomic
number is 13, so the
number of protons is
also 13.
(i) How many protons are in an atom of Aluminium?
13
.
(1 mark)
(ii) How many neutrons are in an atom of Aluminium with mass
number 27?
The atomic mass of an atom is
14
B – Box around the command words.
U – Underline the key words.
G – Go through the question again to
make sure you have not missed anything.
.
the number of protons and
neutrons. In this atom we
know the atomic mass is 27
and the number of protons is
13. So if we take 13 from 27 it
will tell us the number of
neutrons which is 14.
(1 mark)
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