Chapter 6 Notes
• Ionic Bonds vs Covalent Bonds
– Ionic Bonding – Electrons are transferred from one
element to another and they bond due to opposite
charges. Involve metals bonding to nonmetals.
Stronger of the bond types (High melting/Boiling pt)
– Covalent Bonding – Atoms do not transfer electrons but
share them in order to achieve stability. Follow octet
rule (strive for 8 valence electrons except hydrogen
which only wants 2). Involve nonmetals bonding to
nonmetals.
Chapter 6 Notes
• Why do atoms/compounds react/bond?
– Reactions occur only if an atom or compound
will become more stable than it already is. This
is why when you mix some substances nothing
happens, but others you do get a reaction.
Chapter 6
• Repulsive forces vs Attractive forces – Covalent
bonds are made up of these two forces that hold
the atoms together.
– Attractive forces – Opposite charges are attracted to
each other. Thus the electrons of one atom are drawn to
the nucleus of other atoms making an attractive force.
– Repulsive forces – Like charges repel, so as attraction
occurs the electrons of the respective atoms get to close
and repel each other. This is why they often compare
covalent bonds to springs.
Chapter 6
• Bond length and energy
– Bond length is inversely related to its energy.
The longer the bond is the less energy the bond
has and the easier it can be broken. The ideal
covalent bond has what is called maximum
bonding where the attractive forces are exactly
equal to the repulsive forces.
Chapter 6
• The electronegativity of an atom (when a
bonded atom doesn’t equally share electrons
with the other atoms) can create compounds
that are polar. When one end has a positive
charge and the other is more negative.
Water is polar because oxygen has a high
electronegativity causing it to hog
Hydrogens electrons. (+ end and a – end)
Chapter 6
• Intermolecular forces – other weak forces
acting on covalent bonds
– London Forces – weak forces between nonpolar
substances.
– Dipole forces – when two polar substances are
close together the attraction between the
positive and negative ends. Closer they are the
stronger the force. (Hydrogen bonds – when
very close together involving a H)
Chapter 6
• Naming Covalent Compounds
– We use prefixes to represent the number of atoms
involved in the compound:
•
•
•
•
•
•
•
•
•
•
1 – Mono
2 – Di
3 – Tri
4 – Tetra
5 – Pent
6 – Hex
7 – Hept
8 –Oct
9 – Non
10 – Dec
Chapter 6
• Rules to Naming Covalent Compounds
– 1st Simply name the first element. Add the
prefix needed if you have more than one of it.
– 2nd Add prefix needed (always) then name
second element and change ending to ide.
Chapter 6
• Lewis Dot Structures (Electron Dot)
– Using dots to represent the number of valence
electrons in an atom and how they interact in a
chemical bond.
– Single bonds (one shared pair) – Sigma (one
bonding site)
– Double Bonds (2 shared pairs) – Sigma bond
and a Pi bond (bonds over multiple sites)
– Triple bonds (3 shared pairs)
Chapter 6
• Diatomic Elements/Molecules
– Too reactive by themselves so in order to
maintain stability they bond to another of
themselves
• Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine,
Bromine, and Iodine
Chapter 6
• Oxidation Numbers – This is the number of
electrons an atom wants to gain or lose to
become stable (octet).
– Example
• H3PO4
– H = +1
– P = +5
– O = -2
Chapter 6
• Structural, Molecular, and Empirical
Formulas
– Structural Formulas – Drawing of what the
molecule looks like including all parts.
• Ex.
Chapter 6
• Molecular Formulas
– The total number of each element in a
compound
• Ex. C4H10
• Empirical Formula
– Simplest whole number ratio of elements
» C2H5
Chapter 6
• Polymers – Long chains of molecules
• Hydrocarbons – Compounds consisting of
primarily Carbon and Hydrogen
– Organic Chemistry
Chapter 6
• Naming Hydrocarbons
– Based on the number of carbons and how those
carbons are bonded to each other. Also have
special endings for different functional groups
attached in the molecule.
Chapter 6
• Prefixes for number of carbons
–
–
–
–
–
–
–
–
–
–
Meth (1 C)
Eth (2 C)
Prop (3 C)
But (4 C)
Pent (5)
Hex (6)
Hept (7)
Oct (8)
Non (9)
Dec (10)
• Add the prefix CYCLO to the prefix if the carbons form a ring
Chapter 6
• Ending of hydrocarbon name is based on the types
of bonds between the Carbons and if functional
groups present
– All single bonds between C’s no functional groups
ending is ANE
– If you have a double bond or multiple double bonds and
no functional group ending is ENE
– If you have a triple bond between the C’s and no
functional groups ending is YNE
• Hint if the hydrogens are double the carbons +2 you have
single bonds
• If Hydrogens are double the C you have double
• If the Hydrogens are double the C –2 you have a triple bond