Theory Drawing by counting Drawing with patterns
Lewis" Theory of Chemical Bonding
An atom consists of a positively charged nucleus and some negatively charged electrons. These particles interact with each other at all times by means of electrical forces, also known as electrostatic or Coulombic forces.
Electrostatic forces can attract particles together or drive them apart. Oppositely charged particles, like a nucleus (+) and an electron (-), are attracted to one another. Similarly charged particles, like a pair of electrons, repel each other.
Lewis postulated (and it was later confirmed) that an atom"s electrons could be divided into two groups: core and valence. The core electrons stay very close to the nucleus and constantly feel its strong attraction. These electrons are unaffected by neighboring atoms.
Valence electrons, on the other hand, stay farther away from the nucleus and experience much less electrostatic attraction. As a result, these electrons are readily influenced by neighboring atoms.
Test your understanding of this material by filling in the blanks in the following paragraph. Write your answers on a piece of paper and then click "answers" to see the complete paragraph. If you have trouble with this material, try writing the same kind of paragraph about the carbon atom (atomic number 6, mass 12).
The oxygen atom.