Physical properties of the alkali metals
The first vertical column of elements in the periodic table, starting with lithium and ending with francium. Also called the alkali metals. is a vertical column on the far left of the A tabular representation of all known elements in order based on atomic number, eg all the noble gases are found on the right of the periodic table.. The A substance made of one type of atom only. in group 1 are called the alkali metals.
The alkali metals share similar physical and chemical The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point..
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Physical properties
The alkali metals:
- are soft (they can be cut with a knife)
- have relatively low The temperature at which a solid changes into a liquid as it is heated.
The alkali metals also have low A measure of compactness and the ratio of mass to volume. It is usually measured in kilograms per metre cubed (kg/m3) or grams per centimetre cubed (g/cm3).. They are low enough for the first three (lithium, sodium and potassium) to float on water.
Example
| Group 1 element | Melting point (°C) |
| Lithium, Li | 180 |
| Sodium, Na | 98 |
| Potassium, K | 63 |
| Rubidium, Rb | 39 |
| Caesium, Cs | 28 |
| Group 1 element | Lithium, Li |
|---|---|
| Melting point (°C) | 180 |
| Group 1 element | Sodium, Na |
|---|---|
| Melting point (°C) | 98 |
| Group 1 element | Potassium, K |
|---|---|
| Melting point (°C) | 63 |
| Group 1 element | Rubidium, Rb |
|---|---|
| Melting point (°C) | 39 |
| Group 1 element | Caesium, Cs |
|---|---|
| Melting point (°C) | 28 |
Question
The table above shows the melting points of five alkali metals. Use this information to describe how melting point changes in group 1.
Going down group 1, the melting point decreases.
Question
Use the information in the table to predict the melting point of francium, Fr. Explain your answer.
The melting point of francium will be around 27°C. This is because francium is below caesium in the periodic table, so it should have a lower melting point, and the difference in melting point decreases going down from one element to the next.
