Bellwork: Monday 4/9/2012
Naming Covalent Compounds
1.
F2
 Fluorine gas
2.
3.
4.
5.
Cl2
 Chlorine gas
HF
 Hydrogen fluoride
HCl
 Hydrogen chloride
H2S
 Dihydrogen sulfide
6.
7.
8.
9.
NO
 Nitrogen monoxide
NO2
 Nitrogen dioxide
NO3
 Nitrogen trioxide
N2O
 Dinitrogen monoxide
Naming Covalent Compounds- pg 5
Formulas to Names Names to Formulas
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Silicon tetrachloride
Carbon disulfide
Tetraphosphorus pentasulfide
Phosphorus trihydride
Antimony tribromide
Disilicon hexabromide
Carbon tetrafluoride
Dinitrogen trioxide
Sulfur hexachloride
Sulfur trioxide
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
B2H6
ClO2
NBr3
SeF6
XeF6
B6Si
BF3
NF3
P2O5
SiF4
Review: Classifying Chemical Bonds
 Covalent
bonds are those between
non-metals and non-metals
Ex: C (non-metal) and H (non-metal)  CH4
 Ionic
bonds are those between
metals and non-metals
Ex: K (metal) and O (non-metal)  K2O
 Metallic
bonds are those between
metals and metals
METALS
H
vs NON-METALS
H
Metalloids
(dual properties)
B
Al
Si
Ge As
Sb Te
Po At
Opposite charges attract!
Same charges repel!
Understanding how ions react to other elements
will help in naming compounds or coming up
with formulas for the compounds.
To become happy…
Get more?
OR
Get rid of ‘em?
+1
I
+2
II
Be
Li
B
C
What is the
charge?
2e6p++
4p
3p
5p
+4
+3 -4
III
IV
VII
V
VI
VIII
To become happy…
Get more?
OR
Get rid of ‘em?
+1
I
+2
II
Na
Ne
O
N
F
What is the
charge?
8e2e8p
10p
11p
9p
7p+++
-1 0
+4
VII VIII
+3 -4 -3 -2
III
IV
V
VI
+2
Be
+1
I
+2
II
F
2e-
2e-
4p+
9p+
-1
-1 0
+4
VII VIII
+3 -4 -3 -2
III
IV
V
VI
F-1
Be+2
F-1
2e-
2e-
2e-
9p+
4p+
9p+
+1
I
+2
II
Beryllium fluoride
BeF2
-1 0
+4
VII VIII
+3 -4 -3 -2
III
IV
V
VI
Cl -1-1
Cl
Cl -1
+1
I +2
II
Al +3
Cl -1
Al+3
+3
Aluminum chloride
AlCl3
+4
-1 0
-4 -3 -2 VII VIII
III IV
V VI
Ionic Bonding- Page 7

Ionic Bonding- Bond between metal and non-metal
 Transfer of electrons, which results in positive or negative charged
ions that attract to each other (opposites attract)
 The greater the charge, the greater the attraction

Oxidation number- how many electrons an atom has
gained, lost, or shared to become stable; the charge (+ or -)
 Cation- When an atom loses an e-, it loses a negative charge &
becomes a positive ion.
 Anion- When an atom gains an e- it gains a negative charge &
becomes a negative ion.
Element
Name




I
Lithium
Calcium
Chlorine
Selenium
Arsenic
II
# of
Valence e’





1
2
7
6
5
How it’s
Ion it would
going to get
form
happy 





Lose 1 e’
Lose 2 e’
Gain 1 e’
Gain 2 e’
Gain 3 e’
Li+1

Ca+2
-1
 Cl
-2
 Se

As-3

III
IV
V
VI
VII VIII
 Ionic
compounds are electrically neutral
 Goal: Balance out the charges
 Sum of all oxidation numbers in compound = ZERO
 Ex:
Magnesium and Chlorine = Magnesium chloride
 What is the charge of Chlorine? Magnesium?
 How many chlorine ions are needed to balance
the magnesium ions?
2 Cl-1 ions
balance
1 Mg+2 ion
+2
-1
Mg Cl
2
Mg
+2
O
-2
•Mg loses 2 electrons to become stable,
becoming positively charged  Mg+2
•O gains the 2 electrons to become
stable, so O becomes negatively
charged  O-2
+2
-2
Mg O
Magnesium
oxide
Occasionally, you may need more than just one
atom to fulfill each atom’s Octet rule…
“+3” tells that
Nickel has lost
3 e-s to
become (+)
Br
Br
Ni
Br
Ex: Ni + Br =
Nickel (III) bromide
“-1” tells that
each Bromine
atom has gained
1 e- to become (-)
+3
-1
Ni Br3
“3” tells that 3
Bromine atoms are
needed to stabilize 1
atom of Nickel
Ionic bonding: Al + Cl
Cl
Al
Cl
Cl
+3
–1
Al Cl3
Aluminum
chloride
NOW: Try it yourself
on pages 7 & 8!
Bellwork:
Tuesday
4/10/2012
Mg & Cl
1.
2.
Al & Cl
Draw a diagram to show how they ionically
bond to form neutral compounds.
What is the formula? What is the name?
Magnesium chloride
-1
+2
 Mg Cl2
Aluminum chloride

-1
+3
Al Cl3

+1
-1
K F
Na2
+1
-2
O


-1
+2
Mg I2
-2
+2
Be S

+3
Al

Br3
+3
B
-1
F3
-1
 Ca2 Si-4
+2
1
 K2
+1 S-2
+2
-3
Mg3 N2
 Al2 O3-2
+3
Naming Simple Ionic Compounds- Pg 8
When writing the name of ionic compounds:
 The first atom listed…

 Is the cation (+)
 Is capitalized
Ex: Fe2O3
 Is written as the name of that element

The second atom listed…
 Is the anion (-)
 Is written in lowercase
 Is shortened
 Ends in the suffix “-ide”
…is Iron oxide
+3
-2
1)
NaBr
Sodium bromide
2)
CaO
Calcium oxide
3)
Li2S
Lithium sulfide
4)
MgBr2
Magnesium bromide
5)
Be(OH)2
Beryllium hydroxide
Writing Ionic Names to Formulas

When writing an ionic compound’s formula, you need
to find the following:
 The atomic symbols for each element
 Oxidation Numbers - *Remember: these tell you how many
of each atom you need!
○ *NOTE: If the Oxidation Numbers are the same, you
DO NOT need to write them anywhere in the formula! 

ADD this example at the bottom of the “Names to
Formulas” Table!
Calcium oxide
+2
Ca
-2
O
CaO
Now let’s try to write the chemical
symbols for each compound
1)
Potassium iodide
2)
Magnesium oxide
KI
-1
+1
I
K
+2
-2
Mg O
MgO
+3
-1
Al Cl
AlCl3
3)
Aluminum chloride
4)
Magnesium hydroxide
5)
Calcium Oxide
+2
-1
Mg OH
+2
-2
Ca O
Mg(OH)2
CaO
Naming Complicated Ionic Compounds:
Metals that form MORE THAN ONE ION
Periodic Chart of Ions- Page 11
What ions does Iron (Fe) form?
 Ions:
Fe+2 or Fe+3
 Use roman numerals for charge
○ Fe+2 = Iron (II)
○ Fe+3 = Iron (III)
 Assume
you need a roman
numeral for all metals, except:
 Metals in group I and II
 Aluminum (Al), Cadmium (Cd),
Silver (Ag), and Zinc (Zn)
Roman
Charge
numeral
I
+1
II
+2
III
+3
IV
+4
V
+5
VI
+6
Naming Complicated Ionic Compounds:
POLYATOMIC IONS

“more than one atom” ions
Common Polyatomic Ions- Page 9
Ions made up of two or more atoms
 Made of two non-metals

 Covalently bonded together
When they bond with another ion, an ionic bond
forms
 Think of them as a group of atoms that react as ONE!

 Remember: CO and Co are different! The second letter of an
atomic symbol is always lowercase
Naming
Ionic
Compounds
 1st
Word: Name the cation (positive ion)
 Usually the full name of the metal
 2nd Word: Name the anion (negative ion)
 Element:
○ 1st syllable; ends in “-ide”
4  Polyatomic Ion:
○ Unchanged name of polyatomic ion
Ca?SO4-2  Does
the metal have a Fixed
Oxidation Number?
Ca+2
 FIXED- NO roman numeral is used
Fixed
○ You know the charge of the fixed
oxidation
ions!! (Group 1, 2, 13, etc.)
 FORMS MORE THAN ONE ION- YES
number
use roman numeral
Calcium
○ Charge expressed as roman numeral,
in parenthesis, after the name of the
sulfate
metal
CaSO
Naming
Ionic
Compounds
CuSO4
Cu?SO4-2
x + (-2) = 0
x=2
Copper (II)
sulfate
1st Word: Name the cation (positive ion)
 Usually the full name of the metal
 2nd Word: Name the anion (negative ion)
 Element:
○ 1st syllable; ends in “-ide”
 Polyatomic Ion:
○ Unchanged name of the polyatomic ion
 Does the metal have a Fixed Oxidation Number?
 FIXED- NO roman numeral is used
○ You know the charge of the fixed ions!! (Group 1,
2, 13, etc.)
 FORMS MORE THAN ONE ION- YES use roman
numeral
○ Charge expressed as roman numeral, in
parenthesis, after the name of the metal
 The oxidation number on the negative ion
determines the charge on the positive ion
 Total oxidation state must be zero
○ Positive charge must equal the total negative
charge
○ A simple algebraic equation can be used to
determine

Examples #1- Formulas to Names
1. Write the names of the ions
2. Determine the charge of the
positive ion
CuSO3
x
+2
Cu
-2 = 0
SO3
X + (- 2) = 0
You must know the
The charge
sum of on
thethe
positive
sulfite
and negative
charges
ion is
-2
must equal zero
I’m a
+2
+2
polyatomic
X =ion
+2
Copper (II) sulfite
Final Name
Examples #2- Formulas to Names
1. Write the names of the ions
KMnO4
Potassium
I’m a
polyatomic
ion
permanganate
Final Name
If the positive ion has a fixed charge, you are finished.
Examples #3- Formulas to Names
1. Write the names of the ions
2. Determine the charge of
the positive ion
I’m a
polyatomic
ion
NH4NO3
I’m a
polyatomic
ion
Ammonium nitrate
Final Name
If the positive ion has a fixed charge, you are finished.
Examples #4- Formulas to Names
1. Write the names of the ions
X = +2
2. Determine the charge of
the positive ion
X + 2(-1) = 0
Snx (F-1)2 = 0
SnF2
Tin (II) fluoride
Final Name
Examples #5- Formulas to Names
1. Write the names of the ions
2. Determine the charge of
the positive ion
Ba(ClO4)2
Barium
I’m a
polyatomic
ion
perchlorate
Final Name
If the positive ion has a fixed charge, you are finished.
Examples #6- Formulas to Names
1. Write the names of the ions
X = +1
2. Determine the charge of
the positive ion
2X + (-2) = 0
2Cux S-2 = 0
Cu2S
I’m NOT a
polyatomic
ion
Copper (I) sulfide
Final Name
Examples #7- Formulas to Names
1. Write the names of the ions
2. Determine the charge of
the positive ion
Na2Cr2O7
Sodium
I’m a
polyatomic
ion
dichromate
Final Name
If the positive ion has a fixed charge, it is not shown
Examples #8- Formulas to Names
1. Write the names of the ions
2. Determine the charge of
the positive ion
LiCN
Lithium
I’m a
polyatomic
ion
cyanide
Final Name
If the positive ion has a fixed charge, you are finished.
Writing Names to Formulas
 It is easier to write the
formula of an ionic
compound from its
name than the reverse.
 But, you must know the
oxidation number of the
ions!
 Refer to the table of
common polyatomic ions
Example #1-Names to Formulas
1. Write symbols of elements
Aluminum chloride
2. Determine number of ions
(Al +3)x(Cl-1)y
This formula says that
the +3 charge of one Al
atom will cancel the-3
charge from 3 Cl atoms
x(+3) + y(-1) = 0
1(+3) + 3(-1) = 0
Al1 Cl3
If thereFinal
is only Formula
one atom the “1” is
not shown
Example #2-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
Choose the lowest
set of integers that
satisfies the
equation
X= 1
Y 2
2X = 1y
X(+2) + y(-1) = 0
(Co+2)x(BrO3-1)y= 0
Cobalt (II) bromate
Co1(BrO3 )2
If there
is onlyFormula
one atom the “1” is
Final
not shown
Example #3-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X= 1
Y 3
3X = 1y
X(+3) + y(-1) = 0
(Ni+3)x(C2H3O2-1)y= 0
Nickel (III) acetate
Choose the lowest
set of integers that
satisfies the
equation
Ni1 (C2H3O2)3
Final
Formula
If there
is only
one atom the “1” is
not shown
Example #4-Names to Formulas
1. Write symbols of elements
2. Determine number of ions
X =3
Y 1
1X = 3y
X(+1) + y(-3) = 0
(Li+1 )x(PO4-3)y= 0
Lithium phosphate
Li3(PO4 )1
Final
If there
is onlyFormula
one atom the “1” is
not shown
What do you notice about the numbers
in the formula for NiBr3?
+3
-1
Ni(1)Br3
When criss-crossed, they are equal!
 The top numbers for each atom are called its
Oxidation Number

 The oxidation number tells you how many electrons an
atom has gained, lost, or shared to become stable

The sum of the product of the “oxidation numbers”
and the product of the “# of atoms” in the
compound must equal zero
(3 × -1) + (1 × 3) = 0
The oxidation numbers may be may be criss- crossed
to create subscripts in the formula, and used to help
write the chemical formulas
 This is called the “Criss-Cross Method”

+3
-2
Al 2 + O 3

Al2O3
For example: when creating “Aluminum oxide”




Aluminum has an oxidation number of +3
Oxygen has an oxidation number of -2
When you cross them…
…you find the formula for Aluminum Oxide is Al2O3

The criss-cross method tells how many of each atom are
needed to satisfy each atom’s valence shells
+3
-2
 Ex:
Aluminum + Oxygen
Hmm…
We still
have
more
electrons…
we must
need
another
Oxygen!
Al 2 + O 3
Still more
electrons? We
must need another
Oxygen!
FINALLY!!!
We’re done. 
Oops! Now “O” has
extras…Need another “Al”!
Al 2 O 3
 Try
to use the Criss-Cross Method to find the
formulas for the following situations:
 Calcium
 Sodium
 Boron
+ Silicon Ca+2 + Si-4  Ca4Si2
+ Bromine
+ Fluorine
 Potassium
+ Sulfur
+1
Na
+
-1
Br
 NaBr
B+3 + F-1  BF3
K+1 + S-2  K2S
Names to Formulas: Criss-Cross Method
Barium nitrate
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
2+
Ba
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
( NO3-) 2
Now balanced.
Not balanced!
= Ba(NO3)2
Names to Formulas: Criss-Cross Method
Iron (III) chloride
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
Fe3+ Cl-
3
Now balanced.
Not balanced!
= FeCl3
Names to Formulas: Criss-Cross Method
Ammonium sulfate
1. Write the formulas for the cation and
anion, including CHARGES!
(NH4
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
+)
2
SO42-
Now balanced.
Not balanced!
= (NH4)2SO4
Names to Formulas: Criss-Cross Method
Aluminum sulfide
1. Write the formulas for the cation and
anion, including CHARGES!
2. Check to see if charges are balanced.
3. Balance charges, if necessary, using
subscripts. Use parentheses if you need
more than one of a polyatomic ion. Use
the criss-cross method to balance the
subscripts.
3+
Al
2
2S
3
Now balanced.
Not balanced!
= Al2S3