Transcript Chemical Formulas and Equations

Chemical Formulas
and Equations
Chapter 9 – 2
Part 1
Chemical Formulas
• A chemical formula is a shorthand way
to use chemical symbols and numbers to
represent a substance.
C6H12O6
Glucose
• A subscript is a number written below
and to the right.
– It tells how many atoms are in this
molecule.
– If there is no subscript, then there is just
one atom.
Some Basic Rules
• When you have
two elements, you
have two words in
the name
• The first word is
the first element.
• The second word
is the second
element.
Continued
• The second
word also ends
in “IDE”.
• Like oxygen
becomes
oxide.
Writing Formulas for
COVALENT COMPOUNDS
• Covalent compounds are often composed
of nonmetals.
• The names of many covalent compounds
use prefixes.
• Example: Carbon Dioxide & Dinitrogen
monoxide
CO2
N2O
Here are the first ten prefixes:
Prefixes Used in Chemical Names
Mono1
Hexa6
Di-
2
Hepta-
7
Tri-
3
Octa-
8
Tetra-
4
Nona-
9
Penta-
5
Deca-
10
Writing Formulas
Covalent Compounds
• Use the name of compound to write its
formula
• Ex: Carbon Dioxide
• No prefix on first atom indicates 1 atom
• The prefix di indicates 2 oxygen atoms= CO2
• Prefixes always used on second atom C0 =
carbon monoxide
• What is the formula for dinitrogen trioxide?
• ––> N2O3
More Practice
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4.
Dihydrogen monoxide
Silicon dioxide
Carbon monoxide
Hydrogen bromide
H2O
SiO2
CO
HBr
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LET’S TRY IT!
SiF4
Silicon tetrafluoride
SF6
Sulfur hexafluoride
N2O5
Dinitrogen pentaoxide