Chemisty Part 3

Front 1

what is electronegativiy?

Back 1

Electronegativity is the ability of an atom in a molecule to attract electrons to itself.
In general, electronegativity decreases as the atomic radius increases. Larger atoms have lower electronegativities. Within a group of the periodic table, atomic radius increases with atomic number. The electronegativity, therefore, decreases. Across a row of the periodic table, atomic radius decreases with increasing atomic number. The electronegativity, therefore, increases..

Front 2

Electronegativity and Bond Polarity

Back 2

When two atoms are joined by a covalent bond, the bond will have polar character when the electronegativities of the two atoms are different. The atom with the highest electronegativity will have a partial negative charge, while the atom with the lowest electronegativity will have a partial positive charge.

Front 3

Drawing Lewis Structures

Back 3

1. Write the skeletal structure (the arrangement of atoms within the molecule):
2. Count the total number of valence electrons:
Draw a bond between the central atom and each surrounding atom.
Place lone (unshared) pairs of electrons about each terminal atom to complete their octets.
If there are more electrons left, place them as lone pairs on the central atom.
If the central atom has an incomplete octet, use the electrons from surrounding atoms to make double or triple bonds.
Sometimes you just can't complete the octet for a central atom.