To determine the types of bonds, you
have to find out the atom’s
electronegativity. (attraction for
electrons)
 Fewer electron shells= greater electron
negativity
 More electron shells= less electron
negativity

Electronegativity Trends

To determine whether bonds are ionic,
polar covalent, or non-polar covalent,
you need to figure out the difference in
electronegativity between the atoms
that make up a molecule
-If the difference
between 2 atom’s
electronegativity is
small, the bond is likely
to be non-polar
covalent (difference is
less than 0.5)
-If the difference
between 2 atom’s
electronegativity is
larger, the bond is
more likely to be ionic
(difference is greater
than 1.6)
-If the values are
about the same, they
produce polar covalent
bonds (difference is
between 0.5 and 1.6)
NH3 is extremely soluble in the aqueous
solution in a cell
 O2 is relatively insoluble

Ammonia is polar covalent with its bond
because the electronegativity of N is 3.0
and H is 2.1. When subtracted their total is
.9. Since the water molecule is also polar,
the ammonia will dissolve easily.
 The hydrogen in the ammonia will unbond
from the nitrogen and rebond to the water
molecules.
 http://www.johnkyrk.com/cellmembrane.ht
ml
 Ammonia Fountain Experiment

Oxygen gas is non-polar covalent because
the two oxygen atoms have the same
electronegativity, so when subtracted they
equal zero. Since water is polar and oxygen
gas is not, it will not dissolve easily.
 Oxygen gas consists of two oxygen atoms
and when bonded together they have
eight electrons in their valence shells,
making them “happy.” Therefore they have
no interest in rebonding with the water
molecules.


Here’s just a fun video about oxygen
and water. 