Question

How does valence e- relate to an element's chemical properties?

How does it determine the chemical properties of the element? Do valence electrons only determine reactivity?

Answer 1

The more valence electrons an element has, the more reactive it will be. (With exceptions.)

Explanation:

Sodium has only 1 valence electron, so it will want to give so it will fall back on it's octet. Carbon on the other hand has 4 valence electrons, so it's not too worried about giving electrons or getting electrons, it's not going to reach it's octet soon. A halogen, the most reactive of elements, like chlorine or fluorine, have 7 valence electrons. They want a last electron so they can have that full octet, the complete 8-electron ring. A halogen will be most reactive.

And no, valence electrons do not only determine reactivity. Valence electrons can affect how elements bond with each other. For example, when an acid and a base react together to give us water and salt, (NaCl + H2O), the Na electron is ready to give off the electron so badly, that it only connects with Chlorine briefly before departing for it. However, when an alkane like methane (CH4) is made, the carbon and 4 hydrogens stay together in a covalent bond, as they don't want to depart as easily.