Why is the valence shell of an atom important

In the study of chemical reactivity, we will find that the electrons in the outermost principal energy level are very important and so they are given a special name. Valence electrons are the electrons in the highest occupied principal energy level of an atom.

Lithium has a single electron in the second principal energy level and so we say that lithium has one valence electron. Beryllium has two valence electrons. How many valence electrons does boron have?

You must recognize that the second principal energy level consists of both the 2 s and the 2 p sublevels and so the answer is three. In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in s 2 p 6 , has eight valence electrons.

For instance, Magnesium Mg , is in Group 2, which denotes that it has 2 valence electrons. Not every atom has the same number of valence electrons, it depends on the location of the element on the periodic table. The groups on the periodic table typically notes the number of valence electrons an element has with some exceptions.

Valence electrons are the electrons occupying the "valence shell," or outermost shell of the atom. These electrons, in essence, determine the properties of the atom. The reason for this is that atoms really like having a filled valence shell, with a filled shell usually being 8 electrons this is called the octet rule.

In order to fill this shell an atom will either: gain an electron s , lose an electron s , or form covalent bonds. Unsurprisingly, a covalent bond is one formed from valence electrons.

In a covalent bond, both participating atoms effectively "gain" 1 electron per bond formed. In reality, saying the atoms share the electrons is closer to the truth.

But how can we predict what an atom might do with it's valence electrons? Well, first we need to determine how many valence electrons the atom has. This task is actually very simple, when looking at a periodic table.

As a general rule, group 1 elements have 1 valence electron, groups have 2 valence electrons, group 13 have 3, group 14 have 4, group 15 have 5, group 16 have 6, group 17 have 7, and group 18 have 8. What is valency? The electrons rotate around the nucleus, in the same fashion as the sun revolves around the planets. Valence electrons are the electrons that reside in the outermost electron shell of an atom in the highest energy level.

They are important to an atom because the fewer valence electrons that the atom holds, the less stable it becomes. Valence electrons are the most exposed of all the electrons, essentially acting as a protective barrier for the rest of the atom.

Because they are in the highest energy level, they are generally the most involved in chemical reactions since they are the easiest to transfer. The function of valence electrons is to transfer between the atom, gaining or losing electrons in the process, in an effort to bring about stability to the atom. For the most part, eight valence electrons are necessary for an atom to reach a state of stability. As mentioned earlier, the number of valence electrons the atom holds the more stable it is.

In addition to that, the amount of valence electrons in the outer shell determines how atoms interact with one another.