Chemistry warm - up
Write the formulas for the following ionic
compounds.
calcium sulfide
tin (IV) fluoride
sodium sulfate
2. Write names for the following ionic
compounds.
FeCO3
(NH4)2O
1.
Answers
Write the formulas for the following ionic
compounds.
calcium sulfide = CaS
tin (IV) fluoride = SnF4
sodium sulfate = Na2SO4
2. Write names for the following ionic compounds.
FeCO3 = iron (II) carbonate
(NH4)2O = ammonium oxide
1.
Today in Chemistry Class
Today’s Goal . . .
• To be able to write molecular compound
formulas and name molecular compounds
Ionic vs. molecular compounds
◼
Ionic
–
–
–
–
◼
Occurs between metals and non metals
Positive and negative ions attract and balance
Electrons are traded
Strong bond. Mostly solids*
Molecular (covalent)
–
–
–
–
Occurs between non-metals
No need to worry about charges
Electrons are shared
Weaker bonds. Mostly liquids and gases*
* At “room” temperature and sea level
Molecular Compounds
Occurs between non-metals
Top right hand part of periodic table
No metals
Can often combine in more than one way
(NO, NO2, N2O5, etc.)
Traditional System
The traditional naming system uses Latin
prefixes to show how many of each element
there is in the compound
Prefixes
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca
Binary molecular compound
If there is only one atom of the first
element, it doesn’t get a prefix
All other elements, or if there is more than
one atom of the first element, they get a
prefix
First element name doesn’t change
Second element ending changed to -ide
CO2 carbon dioxide
P2O4 diphosphorous tetraoxide
Examples
Naming molecules
NO = nitrogen monoxide
NO2 = nitrogen dioxide
N2O5 = dinitrogen pentoxide
Writing molecular formulas
carbon tetrachloride = CCl4
dinitrogen trioxide = N2O3
The diatomic seven
◼
Seven elements must combine with
another atom of the same element when
there are no other elements
– These are H, N, O, F, Cl, Br, and I
– When we talk about oxygen and hydrogen in
the air, it is O2 and H2
2H2 + O2 → 2H2O
Not
H + O → H2 O
Chemistry
◼
Write the following formulas:
Tricarbon heptafluoride
Nitrogen tetrachloride
◼
Write the following names:
SO3
NO4
How do
formula
2. How do
formula
1.
you recognize whether a chemical
is an ionic compound?
you recognize whether a chemical
is a molecular compound?
Answers
1.
How do you recognize whether a chemical
formula is an ionic compound?
– There is a metal and a non-metal
2.
How do you recognize whether a chemical
formula is a molecular compound?
– There are two or more nonmetals and no
metals
Chemistry
◼
Write the following formulas:
Tricarbon heptafluoride
Nitrogen tetrachloride
Calcium phosphate
Write the following names:
(NH4)2SO3
SO3
NO4
Acids
Have an H at the start of their formula (HCl,
HF, H2SO4)
Compounds that produce hydrogen ions in
water
Compounds are molecular but act ionic in
water meaning charges must be balanced
Binary (only 2 elements)
➢ Given the prefix “hydro“ to indicate they are
binary
➢ The name is modified with an “ic” ending
Examples
Hydrogen + chlorine
Hydrogen + sulfur
HCl (aq) = hydrochloric acid
H2S (aq) = hydrosulfuric acid
Ternary (3+ elements)
NO prefix
If the anion ends in “- ite” the acid ends in
“-ous”
If the anion ends in “-ate” the acid ends in
“-ic”
Example:
Hydrogen + nitrite ion HNO2 Nitrous acid
Hydrogen + sulfate ion
H2SO4 Sulfuric acid
Examples
H2SO4 = sulfuric acid
(because SO42- is sulfate)
HNO2 = nitrous acid
(because NO21- is nitrite)
◼
What would be the name of HBr?
◼
What would be the formula of acetic acid?
◼
Hydrobromic Acid
– only 2 elements, so name starts with “hydro”,
– bromine changed to bromic
◼
HC2H3O2
– No “hydro” in name so more than 2 elements
– “acetic” ends in “ic” so anion must end in
“ate”
▪ Acetate which is -1, so we need only one to
balance the +1 charge of the hydrogen