Electron Dot & Lewis Diagrams by Greg Sra

Electrons are represented by dots in electron dot diagrams. The nucleus is represented by the atomic symbol. There are 4 orbitals having at most 2 electrons per orbital. Each orbital is given an electron before it pairs up. The dots are put into 4 groups.With 8 electrons signifying a closed shell or noble gas.

Lewis Diagrams:

1) Firstly you must find out how many valence electrons are in your chosen elements. Adjust this number by subtracting an electron for each positive charge. Or by adding an electron for a each negative charge in the atom. Then count the electrons remaining.
** You want your atom to become stable, the only way to do this is by having 8 electrons in the outer shell.  (Hydrogen only needs 2 electrons)

2) Then select your central atom. A central atom is the atom that is the farthest away from a closed shell. (Metal Ion goes in center if available) H&F are an exception.Place the electrons so they fill each orbital.

3) Use the remaining valence electrons to fill out the orbitals. Place remaining electrons on the central atom.

4) Make multiple bonds if the central atom is not an octet.

 Covalent Compounds
Two atoms share a pair of electrons to create a full outer shell. This pair is called the Bonding Pair.

Lone pairs or non-bonding pairs are the pair of electrons which do not join together. Single bonds can be represented by 2 dots or a single line.