Chapter 4 – Inside The Atom: Check pg 91
1. Different atoms have different numbers of protons in their nucleus. They
also contain different numbers of particles.
2. The three subatomic particles are protons, neutrons and electrons.
3. A – Electrons
B – Protons
C – Neutrons
D – Nucleus
4. Which of the three subatomic particles are:
a) In the nucleus: Protons and Neutrons
b) Moving rapidly around the nucleus: Electrons
c) The smallest: Electrons
d) Positively charged: Protons
e) Negatively charged: Electrons
f) Neutral: Neutrons
5. If an atom has six protons in its nucleus, it will have six electrons. This is
because there are an equal number of protons and electrons in a an atom.
6. a) The atomic number of a lithium atom is three.
b) The mass number of a lithium atom is seven.
c)
7.
Nucleus
Electrons
A boron atom
b) A boron atom has:

five protons

six neutrons

five electrons
c) A helium atom is different from a boron atom because it only has two
protons, two neutrons and two electrons.
8. a) Isotopes of a particular element all have the same number of protons, or
the same atomic number.
b) Isotopes of a particular element all contain a different number of
neutrons.
9. If two atoms both have 10 neutrons in their nuclei and one has 8 protons
and the other has 9, they are not isotopes. This is because isotopes have
the same number of protons and different amounts of neutrons.
10. A radioisotope is an isotope that is radioactive. This occurs if the number
of neutrons is much greater than the number of protons in the nucleus. In
this case, the nucleus may break up and a nuclear reaction occurs.