# Which of sodium or lithium will be more reactive with oxygen?

I do not understand how you can work out which element will react more readily with another element.

For example, I have lithium (Li) and sodium (Na) and I am trying to work out which element will be more reactive with oxygen. How do I manage to work that out?

• By 'react more', do you mean which reaction proceeds faster and more vigorously? – Binary Geek Mar 15 '15 at 4:55

Reactivity of Group 1 and 2 elements increases as you go down the periodic table. So sodium is more reactive than lithium. Sodium will react with oxygen forming $\ce{Na2O}$ (sodium oxide). Lithium forms lithium oxide $\ce{(Li2O)}$.

Basically, there are general trends (reactivity with acids, air, etc.) down a group or along a period.

• The OP asked "How do I manage to work that out?" whereas you've just stated a fact "Reactivity of Group 1 and 2 elements increases as you go down...". Please consider expanding your answer to include proper reasoning. The below answer instead is much better. – Gaurang Tandon Jul 20 '18 at 14:59

Here is a harder version of the answer above.

1. Sodium has 3 electron shells while lithium has only 2 electron shells

2. Sodium can donate its electrons more easily because the valence electron is further from the nucleus and the force of attraction between both is weaker.

3. Whereas lithium donates its electron less easily because the valence electron is closer to the nucleus and the force of attraction between both is stronger.
4. This is why sodium will "react more" with oxygen compare to lithium