C1 - Atomic Structure and Chemical Reactions Quiz
1. How do you work out the number of electrons, protons and neutrons in an atom?
The atomic number in the periodic table represents the number of protons which is equal to
the number of electrons. Mass number – Atomic number = neutron number
2. Why are few objects made of pure metals?
Pure metals often are too expensive. In a pure metal the atoms are arranged in layers. The
layers can slide easily which means that the metal bends too easily.
3. Why is there no overall charge on an atom?
Because the number of positive protons and negative electrons is equal in an atom.
4. Why do all atoms in the same group have similar chemical properties?
Because they all have the same number of electrons in their outer shell.
5. Why are all group 0 atoms unreactive?
Because they all have a full outer shell.
6. What are the differences in the atomic structure of hydrogen and helium atoms?
Hydrogen has one electron whereas helium has two electrons. Hydrogen has one proton and
zero neutrons, helium has two protons and two neutrons.
7. How many electrons can you fit on each shell around the nucleus of an atom?
Two electrons on the first (inner shell), then eight on the second and third shell.
8. Describe the following reaction in terms of the names of the substances and the number of
atoms involved: 2Al + 3Cl2 --> 2AlCl3
Two aluminium atoms react with three chlorine molecules to form two aluminium chloride
molecules.
9. State and explain the trend in reactivity down Group 1
The reactivity increases. This is because as you go down Group one, the size of the atom
increases as there are more shells. The outer electron gets further away from the nucleus
and is more shielded, it is lost more easily.
10. State and explain the trend in reactivity in group 7.
Reactivity down the group decreases. As you go down the group, the number of shells
increases. This means that the outer shell is further from the nucleus and it is harder to
attract another electron.
