Alkali Metals
Chemistry: AQA GCSE Higher, topic 1.1.24
Alkali Metals
Elements found in Group 1 (found on the left-hand side of the periodic table) are referred to as the alkali metals. Their outer shell has 1 electron in it, which is usually given away in chemical reactions.
Lithium (Li)
- Lithium has the electron structure (2,1).
- Lithium is the least reactive of the alkali metals.
- Lithium burns with a crimson flame when it reacts with oxygen.
- Lithium floats on the surface of water and will release bubbles of hydrogen gas (it effervesces).
Sodium (Na)
- Sodium has the electron structure (2,8,1).
- Sodium is more reactive than lithium because its outer electron is less strongly attracted to the positively charged nucleus. This is because it is a greater distance from the positive charge of the atom's nucleus.
- The metal floats on the surface of water, which releases enough heat to melt the sodium. The sodium moves quickly across the surface of the water.
- Sodium burns with a yellow/orange flame when it reacts with oxygen.
Potassium (K)
- Potassium has the electron structure (2,8,8,1).
- Potassium is more reactive than lithium and sodium because its outer electron is least strongly attracted to the nucleus.
- The metal floats on the surface of water, and has a similar, but more vigorous, reaction compared with sodium.
- Potassium burns with a lilac flame when it reacts with oxygen.
Test yourself on Alkali Metals
Why is sodium more reactive than lithium?
Which alkali metal is not very reactive, burns with a crimson flame in oxygen and has the electron structure (2,1)?
What is the collective name for the elements in Group 1 of the periodic table?
Why does sodium melt as it reacts with water?