The atom

Getting stable

 

Now remember the two atoms that were very stable. They were helium and neon. Helium has an electronic configuration of 2, while neon has an electronic configuration of 2,8. Helium has the first energy level full while neon has both the first and the second full. Full energy levels make the atom very stable and the atom will give, take or even share electrons so it can have a full outermost energy level. Transferring electrons from atom to atom is the basis of a number of chemical reactions.
Electrons are the only subatomic particles that can move from atom to atom during chemical reactions and atoms will give take or share them so they can look like helium or neon.

Lets see how this is done. Click on the elements to see further explanations

Lithium has an electronic configuration of 2,1. It will give away its electron in the second energy level so that it looks like stable helium with an electronic configuration of 2. Now with only two electrons and 3 protons the atom has an imbalance of charge. That is, it has 3 positives and only two negatives. The overall charge is the sum of these two (+3-2 =+1) is a charge of +1.

Beryllium has an electronic configuration of 2,2. It will give away its two electrons in the second energy level so that it looks like stable helium with an electronic configuration of 2. Now with only two electrons and 4 protons the atom has an imbalance of charge. That is, it has 4 positives and only two negatives. The overall charge is the sum of these two (+4-2 =+2) is a charge of +2

Boron has an electronic configuration of 2,3. It will give away its three electrons in the second energy level so that it looks like stable helium with an electronic configuration of 2. Now with only two electrons and 5 protons the atom has an imbalance of charge. That is, it has 3 positives and only two negatives. The overall charge is the sum of these two (+5-2 =+3) is a charge of +3

Nitrogen has an electronic configuration of 2,5. It will take three electrons into the second energy level so that it looks like stable neon with an electronic configuration of 2,8. Now with 10 electrons and 7 protons the atom has an imbalance of charge. That is, it has 7 positives and 10 negatives. The overall charge is the sum of these two (+7-10 =-3) is a charge of -3

Oxygen has an electronic configuration of 2,6. It will take two electrons into the second energy level so that it looks like stable neon with an electronic configuration of 2,8. Now with 10 electrons and 8 protons the atom has an imbalance of charge. That is, it has 8 positives and 10 negatives. The overall charge is the sum of these two (+8-10 =-2) is a charge of -2

Fluorine has an electronic configuration of 2,7. It will take an electron into the second energy level so that it looks like stable neon with an electronic configuration of 2,8. Now with 10 electrons and 9 protons the atom has an imbalance of charge. That is, it has 9 positives and ten negatives. The overall charge is the sum of these two (+9-10 =-1) is a charge of -1

Sodium has an electronic configuration of 2,8,1. It will lose an electron from the second energy level so that it looks like stable neon with an electronic configuration of 2,8. Now with 10 electrons and 11 protons the atom has an imbalance of charge. That is, it has 11 positives and 10 negatives. The overall charge is the sum of these two (+11-10 =+1) is a charge of +1

How do we know when an atom will give or take electrons? Two very simple rules.

Atoms with 3 or less electrons in the outer energy level (with hydrogen the only exception) will give electrons away.

Atoms with 4 or more electrons in the outer energy level will take electrons.

Click to see an interesting activity to better explain the reasons why atoms are more stable with full energy levels. (best suited for junior science classes)
.Exercises