Transcript Writing compounds

BETWEEN YOU AND A PARTNER, WRITE THE
FOLLOWING COMPOUNDS ONTO SEPARATE SLIPS
OF PAPER
NaCl
Na2SO4
AlCl3
CO2
CuO
PF5
C2H6
NH3
CCl4
Li2S
SO3
CaCl2
 Challenge:
group compounds according to
(unknown) categories

Hint 1: There are only 2 groups

Hint 2: There are 6 compounds in each group


Hint 3: The numbers in the compound have
nothing to do with the grouping
Hint 4: Look at the types of elements in each
compound (metals and nonmetals)
COMPOUNDS
Writing chemical formulas for ionic and covalent
compounds and acids
IONS

What is an ion?


How does it gain that charge?


An atom with a charge
Gains or loses ELECTRONS
What are the 2 types of ions?

Cation + Anion
NAMING MONOATOMIC IONS
Symbol
Name
Symbol Name
Na+1
Sodium ion
N-3
Nitride
Mg+2
Magnesium ion
O-2
Oxide
Ca+2
Calcium ion
F-1
Fluoride
Al+3
Aluminum ion
Cl-1
Chloride
K+1
Potassium ion
I-1
Iodide
H+1
Hydrogen ion
P-3
Phosphide
Ag+1
H-1
Li+1
Br-1
Be+2
S-2
What are the general trends when naming cations/anions?
Anions always end in ________
POLYATOMIC IONS
 An
ion that is formed when several atoms
combine.
 Acts
as an individual ion in a compound
and its charge applies to the entire group
of atoms.
POLYATOMIC IONS
NO3-1
NO2-1
SO4-2
SO3-2
PO4-3
PO3-3
OH-1
CN-1
C2H3O2-1
Nitrate
Nitrite
Sulfate
Sulfite
Phosphate
Phosphite
Hydroxide
Cyanide
acetate
ClO4-1
ClO3-1
ClO2-1
O2-2
CO3-2
NH4+1
Perchlorate
Chlorate
Chlorite
Peroxide
Carbonate
Ammonium
NAMING
cation 1st anion 2nd
Binary compounds
only 2 elements present
always end in –ide
Tertiary compounds
3 or more elements present
refer to polyatomic ions
NAME THE FOLLOWING COMPOUNDS
MgS
Li2O
CaBr2
Na2SO4
Fe3N2
K3PO4
Magnesium sulfide
Lithium oxide
calcium bromide
Sodium sulfate
Iron nitride
Potassium phosphate
 Name
the following compounds
Li2CO3
Na3N
Mg(C2H3O2)2
Zn(OH)2
WHAT ARE IONIC COMPOUNDS MADE UP
OF?
 IONS

Cation + Anion
 The
best way to recognize an ionic
compound is the presence of a
__________
 METAL
There is one exception to this rule – it is
the only cation that does not have a
metal in it
 Ammonium

HOW DO YOU DETERMINE THE CHARGES
OF YOUR IONS?
 Look
at the periodic table - all elements in
same group have same oxidation number
 Which elements are positively charged?
 All metals
 Which elements are negatively charged?
 Mostly nonmetals
 What group of elements do NOT have a fixed
charge?
 Transition metals
 How
do you determine the charge of a
transition metal?
 Roman numeral – the charge is always
positive
 What
is the overall charge of a compound?
 ZERO – the charges of your ions balance
each other out
Superscript = oxidation
number, determined by how
many electrons are lost or
gained
X
1
2
Subscript = tells the
number of atoms that are
present in a molecule of
the compound
WHERE DO THESE SUBSCRIPTS COME
FROM?

Polyatomic ion subscripts NEVER change


If magnesium and fluorine bond, what will
happen?


PO4-3 is always phosphate
Determine first how many valence electrons each has
The subscripts tell you how many atoms you need
of each type in order for the charge to balance out
CRISS CROSS METHOD

ONLY THE NUMBERS
CRISS-CROSS, NOT THE
CHARGE!!
If you have one atom with a
+2 charge and one with a -2
charge, how many of each do
you need to cancel out the
charge?
 Be sure to simplify if you can
after criss-crossing!

When to simplify
Sn+4 and O-2
When not to simplify
Na+1 and SO4-2
** never touch the subscripts in the polyatomic
ions!!
What to do with polyatomic ions
Al+3 and NO3-1
** if any number other than 1 comes down to a
polyatomic ion, put it in parentheses
WRITE THE BALANCED CHEMICAL FORMULA
FOR THE FOLLOWING COMPOUNDS…
 Magnesium
fluoride
 Copper (II) chloride
 Calcium nitride
 Lithium nitrate
 Zinc sulfate
 Tin (IV) oxide
 Calcium hydroxide
 Silver phosphate
 Chromium (VI) sulfide
Look at the ending of
the compound to figure
out what to use
What does the roman
numeral let you know?
The charge of the
metal. Is it positive
or negative?
ALWAYS Positive
What 2 transition
metals have fixed
charges?
DETERMINING CHARGE OF TRANSITION
METAL
 When naming compounds with transition metals,
you must determine the oxidation number

Backwards criss-cross
Fe2O3
vs.
FeO
Determine the oxidation numbers for the transition
metals in the following compounds
CuCl2
NiSO4
CrO3
SnS2
*** Only use roman numerals for compounds with transition
metals (or Sn or Pb)!!!
TAKE OUT THE WORKSHEET FROM
YESTERDAY…
Warm up:
Name or write the formula for the following
compounds
Aluminum sulfate
Copper (II) hydroxide
NH4Cl
CaS
COVALENT COMPOUNDS


If a compound doesn’t contain a metal (or
ammonium) then you more than likely have a
covalent compound
Electrons are shared – no ions are formed
Prefixes are used to determine the chemical
formula
 NO CRISS CROSS!!

PREFIXES
1
2
3
4
5
6
7
8
9
10
Mono
Di
Tri
Tetra
Penta
Hexa
Hepta
Octa
Nona
Deca
Pre- means what?
before
______ 1st element
prefix
______ 2nd element
(ends in –ide)
prefix
*** never use mono- on the first element
NAME OR WRITE THE FOLLOWING
COVALENT COMPOUNDS:
** never simplify
C2H4
P4S5
B2Si
NF3
Sulfur hexafluoride
Hexaboron disulfide
Dinitrogen tetroxide
Dicarbon tetrahydride
Tetraphosphorus pentasulfide
Diboron monosilicide
Nitrogen trifluoride
SF6
B6S2
N2O4
BE CAREFUL!!!!

Covalent compounds are easy – but don’t start
mixing up the rules!!!
Ionic
Covalent
Contains a metal or NH4
Only nonmetals
No prefixes
Use prefixes
Criss-cross
No criss-cross
Simplify
Don’t simplify
binary compounds always
end in –ide!
WARM UP
Name the following compounds:
PF3
Li2S
Mg(NO2)2
Write the formulas for the following compounds:
Aluminum carbonate
Dinitrogen hexoxide
Iron (II) nitride
NAMING ACIDS

Recognizing acids – Hydrogen is the CATION
ex.
HCl
vs.
NaH
not in cation position
2 types:
binary
H and 1 other element
tertiary/oxyacid
H and a polyatomic ion
NAMING ACIDS
Binary
hydro___________ic acid
stem
Tertiary
stem
_____________ic acid (ends in -ate)
or
_____________ous acid (ends in -ite)
“I ate it and it was icky”
PRACTICE
HF
H 2S
H 3P
H3PO4
H2SO3
HC2H3O2
WRITING FORMULAS FOR ACIDS
Use criss cross method – need to figure out your
ions
 What will always be your cation in an acid?


1.
Figure out if it is binary or tertiary
1.
2.
3.
4.
Hydrogen
Binary acids begins with _____ in their name
If binary, figure out the element
If tertiary, look at the ending to figure out
which polyatomic ion you need to use
Criss cross your charges
PRACTICE
Hydrobromic acid
Sulfuric acid
Chloric acid
Hydronitric acid
Nitrous acid