Transcript Nomenclature Notes

Bonding & Chemical
Nomenclature
Chapter 8 & 9
Some Key Terms
1. Chemical bond – a mutual electrical attraction
b/w the nuclei and valence electrons of
different atoms that binds the atoms together.
2. Ionic Bond – the electrostatic attraction of
oppositely charged particles (cations & anions)
3. Ionic Compound – Molecules that contain ionic
bonds where the positive and negative
charges are equal.
4. Metallic bonding – chemical bond that results
from the attraction b/w metal atoms and the
surrounding sea of electrons
Key Terms cont.
5. Covalent bond – results from the sharing of
electrons
6. Molecular compound – molecules that contain
covalent bonds and whose simplest units are
molecules.
7. Chemical Formula – a formula that indicates
the relative #’s of atoms of each kind in a
chemical compound. Uses atomic symbols
and numerical subscripts. Ex. NaCl, Mg(OH)2
8. Polyatomic Ion – A charged group of
covalently bonded atoms. Contains two or
more different elements
Key Terms cont.
9. Molecule – Neutral group of atoms held
together by covalent bonds.
10. Oxidation number - # assigned to an atom in a
molecular compound or ion that indicates its
distribution of electrons (charge)
11. Binary Compound – A compound composed of
2 different elements
12. Octet rule – Chemical compounds tend to form
so that each atom has an octet (8) electrons in
the highest energy level except for a few of the
smallest atoms.
What are ions?
• Ions are atoms that have lost or gained
electrons to become positively or negatively
charged.
• Metals tend to form positively charged ions
called cations
• Nonmetals tend to form negatively charged
ions called anions.
• To determine the charge of an ion we must
look at the arrangement of VALENCE
ELECTRONS.
Review of Lewis Dot Diagrams
• Lewis dot diagrams show an elements
valence electrons as dots around the
element’s symbol.
• To determine valence electrons for main
group elements refer to the “A” group
number.
• REMEMBER – a valence electron is an
electron in the outermost energy level
Formation of Ions
• Label your periodic table with the following
GENERAL charges above each group:
•
•
•
•
•
•
•
•
Group 1A =
Group 2A =
Group 3A =
Group 4A =
Group 5A =
Group 6A =
Group 7A =
Group 8A =
+1
+2
+3
+/-4
-3
-2
-1
0
Writing Ionic Formulas
• CRISS-CROSS
• Look up the charge for the first element, then look up the
charge for the second element or group (polyatomic ion)
and then criss-cross to get the subcripts
• If the charges are equal and opposite they cancel and no
criss-cross is needed.
• Examples:
– Sodium chloride
– Potassium sulfide
– Magnesium phosphate
Naming Binary Ionic
Involves a metal and a nonmetal
• Name the metal
• Name the nonmetal and change the
ending to –ide.
Examples
NaCl
K2O
BaF2
Naming Binary Ionic with
transition metals
Still Metal – Nonmetal. We use this method only if the metal
can have a variable charge/oxidation number. The majority
of these will be transition metals. Exceptions to memorize:
Silver (Ag+1), cadmium (Cd+2), zinc (Zn+2)
1.
2.
Name the metal
Using a roman numeral write the oxidation number of
the metal in parenthesis. To get the oxidation number
uncriss-cross the charges.
3. Name the nonmetal and change the ending to –ide
Examples
CuBr2
Fe2O3
Naming Ionic Compounds with
Polyatomic Ions
1. Name the metal
2. Name the polyatomic ion
3. Be sure to use a roman numeral if it is
necessary (transition metals)
Examples
LiNO3
KMnO4
Na2CO3
Naming Binary Molecular
(covalent) Compounds
Involves a bond b/w 2 nonmetals
1. Name the 1st nonmetal. Use a prefix if there is
more than one.
2. Name the 2nd nonmetal ALWAYS use a prefix.
Change the ending to –ide.
Prefixes
Examples
NO
P2O5
SO3
1 mono-
6 hexa-
2 di-
7 hepta-
3 tri-
8 octa-
4 tetra-
9 nona-
5 penta-
10 deca-
Writing Formulas for Molecular
Compounds
• Write the symbol for each of the elements involved
• Look at the prefixes and decide what numbers are being
represented.
• Write those numbers as subscripts to the right of the
elements symbol in the formula
• Examples:
– sulfur trioxide
– Carbon monoxide
– Dinitrogen monoxide
Naming Binary Acids
• Acids generally start with Hydrogen
1. Binary Acids (H with one element)
– Use the prefix hydro– Then add the name of the second element
and change the ending to –ic acid
– HCl hydrochloric acid
– HBr hydrobromic acid
– HI
hydroiodic acid
Naming Acids with
Polyatomic Ions
• Hydrogen with a polyatomic ion (group of
atoms with a charge)
– Identify the polyatomic ion
– Change the ending accordingly:
• -ate to –ic acid
• -ite to -ous acid
• (Do NOT use the prefix Hydro-)
• H2SO4 sulfuric acid
• HNO3 nitric acid
• HNO2 nitrous acid
Writing Formulas for Acids
• For acids you must look up the charges of the ions
invovled.
• Hydrogen is the first element – look up its charge
• Then if it is a hydro- prefix acid look up the second
element and charge and criss-cross
• If it is an –ic acid or and –ous acid, you must look up the
polyatomic ion and its charge then criss-cross
• Example:
– Hydrobromic acid
– Sulfuric acid
Naming simple bases
• Common bases for us will end in –OH or
hydroxide ion
• So name the first element then name the
hydroxide
– NaOH
sodium hydroxide