Differences between Covalent Bonding and Ionic Bonding

Why this works

Electronegativity- ability of an atom to attract and hold bonding electrons.

Elements with a large difference in electronegativity will form an ionic bond, elements with a small difference will form covalent bonds.

Electronegativity Chart

What about the middle ground?

What if the difference in electronegativity isn’t large or small but in the middle?

For example H (2.1) and O (3.5) These elements form a polar covalent bond. Polar Covalent Bond- unequal sharing of

electrons in the bond the electrons stay around oxygen more than

hydrogen

Polar covalent

4 electrons occupy this cloud.

Notice how much larger the cloud is around oxygen as compared to hydrogen.

Do any bonds have an equal sharing? Yes, (normally the same element) when

elements are equally electronegative like O2

In fact, anything with a very slim difference (less than 0.5) in electronegativity will pretty much equally share electrons.

Nonpolar covalent bonding- equal sharing of electrons in a bond

Bonds electron density

Why it is called polarpolar implies different ends have different chargessimilar to a magnet.

Oxygen

H

H

Water has 2 polar covalent bonds, meaningthe electrons stay around oxygen more than H

That makes thisside negative

and this side positive

Denoting positive and negative

Oxygen

H H

+

The symbol (lower case delta) means partial

+

Neither side is completely positive or negative,they are only partially positive and partially negative.

2-

Effects of shape on polarity

Water is polar because it is bent

OH H

-

+

CO2 is nonpolar because it islinear

O OC-+

Center of positive and negative charge is in The same place.

To be polar youneed a positive endand a negative end

Conservation of… Mass Mass is neither created nor destroyed in a

reaction. The mass of the reactants is equal to the mass

of the products. This is often forgotten, or is a common

misconception due to certain reactions.

Reactions in a water solution What happens when ions dissolve in water? Ions become free floating. In a solid, they are “stuck together”. In a solution, they are free to move.

Conduction of Electricity Pure water does NOT conduct electricity ~there are no (+) and (-) particles to move the

elctrons For water to conduct electricity you must

dissolve an electrolyte in it. Electrolyte- any substance that increases a

solvent’s conductivity

Precipitation Reaction

~ a reaction where a solid product is produced from dissolved reactants

Precipitate- solid falling out of solution It will appear to make the solution cloudy

homework

Read section 6.6 and 6.7 Pg 213-215 Prob 23-30; 78-81