The table Boiling point/°C
1360
Melting point/°C
180
Potassi
This a
The el
Mass number
Element
7
3
98
900
11
19
three of the metals in Group 1.
Atomic number
lithium, Li
sodium, Na
23
63
777
39
potassium, K
As you can see, the atomic number increases as you go down the group. The mass
number also increases as you go down the group. These increasing numbers show you
that the size of the atom is increasing.
When you look at the melting points you can see that they go down as you go down
the group. The next metal down in the group is rubidium. We can predict it would
have a melting point lower than 63°C.
Questions
1 Where in the Periodic Table do you find the metals? In the eter-group
2 What is the trend shown in the boiling points of Group 1 elements?
3 What prediction can you make about the boiling point of rubidium?
4 How many more electrons than lithium does an atom of sodium have?