Name the three main groups in Use the Periodic Table of Elements to write down the symbol
Table are arranged. Give an example of one elen
group
2. Identify the following as an element, a compound or a mixture:
a) magnesium oxide
b) air
c) hydrogen gas
3.
of an element that:
a) is a non-metal in Group 13
b) has five protons in the nucleus of one atom
c) is in Group 2 and in the second period
d) has eight electrons in one atom
e) has 28 subatomic particles in the nucleus of one atom
f)
has seven neutrons in the nucleus of one atom
4. The boiling point of pure water is 100 °C at sea level. If a certain
sample of water boils only at 101,5 °C, what do you know abou
the sample? Give a reason for your answer.
5. What do we call the chemical reaction that uses:
a) an electrical current to decompose a compound?
b) heat to decompose a compound?
6. Draw a diagram to illustrate the decomposition of copper chloride with an electric current ​