View
216
Download
1
Category
Preview:
Citation preview
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
Recommended