- #1
Calpalned
- 297
- 6
We know that lithium, sodium and potassium tarnish when exposed to air, but rubidium and cesium catch on fire. Why is there such a huge jump in reactivity between Rb and K?
Alkali metals are highly reactive due to their low ionization energy, which allows them to readily lose electrons and form positive ions. They also have a low electronegativity and high atomic radius, making it easy for them to bond with other elements.
Alkali metals react vigorously with water, producing hydrogen gas and a strong base. This is because they have a strong tendency to donate their outermost electron, forming a positively charged ion that reacts with the water molecules.
As you move down the group, the atomic radius of alkali metals increases, making it easier for them to lose their outermost electron. This is due to the shielding effect of inner electrons, which reduces the attraction between the outermost electron and the nucleus.
The most reactive alkali metal is francium, which is located at the bottom of the group. It has the largest atomic radius and the lowest ionization energy, making it the most likely to lose its outermost electron.
Alkali metals react with halogens, such as chlorine and fluorine, to form ionic compounds. The alkali metal donates its outermost electron to the halogen, forming a positively charged ion, while the halogen accepts the electron, forming a negatively charged ion. These compounds are highly reactive and can be explosive.