Atoms and their electrons

It is hard to explain why atoms react with each other and produce energy in chemical reactions. One very successful way of introducing the concept of atoms and electrons in chemical reactions is outlined below. It attempts to give students an understanding as to how and why atoms transfer electrons from each other in chemical reactions.
Just for one moment picture an atom as an apartment building. The electrons are its tenants. Each apartment building looks identical. Each has two levels(even though there are more), 2 apartments on the first and 8 on the second level. The higher the level the more energy the tenants(electrons) need to get there. Think of a staircase, the higher the staircase the more energy you require to get to the top.

The tenants (electrons) stay in these apartments. Now each level has one light switch. If there is one or more tenant(electron) on any level the entire level is energised with light.

Atoms are very strange little things. They have this unique habit of always wanting to be 100% energy efficient.

Lets see what we mean by 100% energy
efficient.


A representation of the atom. This is not the way atoms look but we will think of them as little apartment buildings.

Hydrogen needs one more electron to be completely efficient.

Helium has two electron and has a full first energy level.

Take hydrogen for example, it has one electron in the first level. The entire first level is energised. Is this 100% energy efficient? Click to see how hydrogen reacts with oxygen to exchange eelctrons.


NO! Why?


Now take helium, it has two electrons
in the first level. The entire first level
is energised. Is this 100% energy
efficient?


YES! Why?
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