CHEMICAL BONDS (Ionic and Covalent Bonds)
Part 1
Textbook Pages: 52-63
Chemical Bonds: The forces that attract atoms to each other in compounds.
Ionic Bond:
Covalent Bond:
*** A filled valence shell makes atoms stable. Therefore, when bonds form
between atoms, they do so in a way that gives each atom a
Octet Rule:
Ionic vs. Covalent:
PROPERTY
IONIC COMPOUNDS
COVALENT
(MOLECULAR)
COMPOUNDS
Types of elements
involved
What happens to
electrons?
Type of bond that forms
State at Room
Temperature
Solubility in Water
Electrical Conductivity in
Solution
Old Way of Bond Classification:
BEFORE, classification of bond type was easy. All we did was look at the types
of elements in the compounds and that would tell us the bond type.
e.g. NaCl
e.g. CH4
Consider the following compound:
BeH2
Our previous experience and knowledge would seem to tell us that this is an
___________ compound.
However, the classification is incorrect! It is in fact a _____________ compound!
Therefore, our “inspection” method of classifying bond type is no longer sufficient
to predict the classification of bond type.
We must look to ELECTRONEGATIVITY for the answer!
Electronegativity:
By comparing the electronegativity values of two elements involved in a chemical
bond, we can determine whether they will transfer electrons
, or share electrons
. For elements that
share electrons, we can also determine whether the sharing will be unequal
or equal
.
IONIC
POLAR COVALENT
TRUE COVALENT
e.g. Classify the type of bond present for each of the following compounds:
CH4
B2S3
CaO
H2O
IONIC COMPOUNDS – FORMATION & LEWIS STRUCTURES
Ionic compounds ____________ electrons to produce positive _________
and negative ____________. The oppositely charged ions
___________each other. The attraction is what holds the ions together.
The attraction is __________. It is this attraction that gives ionic compounds
HIGH ______________ and makes them __________ at room temperature.
Since the ions are ___________, when they dissolve in water, they can
_________________ by facilitating the movement of the ___________
through the liquid.
RULES FOR DRAWING LEWIS STRUCTURES FOR IONIC COMPOUNDS
1. Write the ionization equation of each element to start.
Use this to determine the number of electrons transferred by each
element.
Multiply the equations (if necessary) to equalize the number of electrons
lost and gained.
2. Each ion goes in a set of square brackets [ ] with the charge outside the
bracket corresponding to the number of electrons lost or gained.
3. Alternate ions of opposite charges.
e.g. Sodium + Chlorine
e.g. Calcium + Bromine
e.g. Aluminum + oxygen