Transcript Chapter 4

Compound Names and
Formulas
Chemistry
Learning Objectives
• TLW relate chemical behavior of an element including
bonding, to its placement on the periodic table (TEKS 4.D)
• TLW understand the chemistry of ionic, covalent, and
metallic bonding (TEKS 8.A. & 8.B.)
• TLW be able to identify, name, and write formulas for:
– Binary ionic, covalent, and metallic compounds
– Polyatomic ionic, covalent, and metallic compounds
– Ionic compounds for metals that can have multiple charges (use of
Roman Numeral nomenclature)
– Acids, bases, salts, and specialty compounds
– TEKS 11.A. & 11.B
Agenda
• Binary Compounds
–
–
–
–
Naming Ionic Compounds
Naming Covalent Compounds
Naming Metallic Compounds
How to Write Chemical Formulas
• Polyatomic Compounds
–
–
–
–
Naming Ionic Compounds
Naming Covalent Compounds
Naming Metallic Compounds
How to Write Chemical Formulas
• Group Practice Along the Way
• Independent Practice
How to Write Binary Chemical Formulas
1. Writing Ionic Chemical Formulas
a. steps:
1. List the symbol for each ion
2. Find the charge for each symbol
3. The charge is found by the number of
electrons an element has to lose or
gain to get 8 valence electrons
4. Criss-cross the charges
b. ex. Aluminum fluoride
Aluminum is Al
fluoride is F
Al has a charge of 3
F has a charge of 1
Criss-cross the charges
AlF3
Practice
1. Barium phosphide
Ba = barium
P = phosphide
Ba is in Group 2; a charge of 2
P is in Group 15; a charge of 3
Criss-cross charges:
Chemical formula: Ba3P2
How to Name a Binary Compound
A binary compound is comprised of only two
different elements and the compound does
not carry a charge (example ~ NaCl)
1. Naming Ionic Compounds
a. Between metals and nonmetals
b. Steps
1. Look at the chemical formula
2. Write out the name for the 1st element
which is the metal
3. Write out the name for the 2nd
element
which is the nonmetal
BUT – you must change
the ending to “ide”
Ex. Fluorine becomes
fluoride
c. Ex. NaCl
1. Na is sodium
2. Cl is chlorine
3. So the name is Sodium
Chloride
…notice the ending on
chloride
Practice:
1. CaS
Ca is calcium
S is sulfur
Name: calcium sulfide
2. AlN
Al is aluminum
N is nitrogen
Name: Aluminum nitride
Group Activity
• Calling All Relay Teams
• For each binary compound on the board write
the following:
–
–
–
–
–
Lewis Dot Diagram
VSEPR Shape Name
Type of Bond
Name (if you are given the formula) or
Formula (if you are given the compound’s name)
Individual Practice
• Practice Set 1 - Naming Ionic Compounds and
Writing Formulas
Naming Compounds & Writing
Formulas for Metals That Have
Multiple Charges (Transition Metals)
• Certain transition metals can have multiple
charges
– Example Cr2+ and Cr3+
• When writing compound names involving
these ions use Roman numerals
– The Roman Numerals tell you the charge
• Iron(III) = Fe3+
Iron(II) = Fe2+
– Examples: Iron(II) chloride – FeCl2,
– Iron(III) oxide – Fe2O3
Practice
Write the formula for Copper(II)
sulfide
Copper (II) = Cu 2+
Sulfur = S 2Since they have charges that will
cancel each other the formula will
be CuS
2. Naming Covalent Compounds
a. Between nonmetals and
nonmetals
b. Steps
1. Look at the chemical formula
2. Look at the subscript
number for each element
Ex. C3O4
3. Use the prefix that goes with
the subscript number
• If there is no number – it is one or mono
• The 1st element is the element furthest
to the left
...Except for oxygen which is always last
nd
4. The 2 element gets the “ide”
ending
Number of Atoms
1
2
3
4
5
6
7
8
9
10
Prefix to Use
mono di – or bitri tetra penta hexa heptaocta nona deca -
c. Ex. CO2
C is carbon
no number – no prefix
O is oxygen
number is 2 so it gets the
prefix di
Name: Carbon dioxide
Practice
1. N2O4
N is nitrogen
number 2 so it is dinitrogen
O is oxygen
number is 4 so it’s tetraoxide
Name: dinitrogen tetraoxide
2. C4H3
C = carbon
4 is tetra
H = hydrogen
3 is tri
So name =
tetracarbon trihydride
Group #
Charge
1
+1
2
+2
3
+3
4
+4
5
+5
6
+6
7
+7
8 - 10
Varies
11
+1 usually
12
+2 usually
13
-5
14
+4
15
-3
16
-2
17
-1
18
0
2. Writing Covalent Chemical Formulas
a. Steps:
1. List the symbol for each ion
2. Look at the prefixes and
write the number (subscript)
b. ex. Dinitrogen tetraoxide
1. dinitrogen is N
2. tetraoxide is O
3. Chemical formula: N2O4
DO NOT CRISS-CROSS
Practice
1. trichloride monoxide
Cl is chloride
O is oxide
tri is 3
mono is 1
Cl3O
Naming Polyatomic Compounds
• Polyatomic compounds are tightly bonded groups of
atoms that behave as a unit and carry a charge
(Sulfate – SO42-)
• Most end in –ite or –ate
– Exceptions ammonium cation (NH4+), cyanide (CN-), and
hydroxide (OH-)
• When a polyatomic ion begins with H you can
imagine it combined with another polyatomic ion
(HCO3- is H+ and CO32-)
• Polyatomic compounds do not exist on their own in
nature – they readily combine to form other
compounds
Common Polyatomic Ions
How to Write Polyatomic Chemical Formulas
Steps: Write formula for aluminum nitrite
1. List the symbol for each element
ex. – Al for aluminum
2. List the symbols in polyatomic compound
ex. – NO2 for nitrite
2. Find the charge for each ion (whether a single
element or polyatomic compound)
3.b. The charge for element found by the number of
electrons an element has to lose or
gain to get 8 valence electrons (Al3+)
3.a. See chart for charges for common poly-ions
(NO2 -)
4. Criss-cross the charges – ex. Al(NO2)3
Practice
Write the formula for Vanadium(V)
carbonate
Vanadium (V) = V 5+
Carbonate = CO3 2Use the criss-cross method on
charges to determine formula
V2(CO3)5
Cooperative Learning
• In pairs:
– Create flash cards with polyatomic compound
name on one side and the compound’s formula
on the other
– Create at least one 3-D polyatomic compound
using Styrofoam® and/or fuzzy balls – pay
attention to the geometry (remember VSEPR…)
Independent Practice
• Worksheets – in class and homework