Grade 10 Chemistry
5.9: Polyatomic Ions
Polyatomic Ions


Ex:

These behave exactly like ______________ to produce a ____________ with an overall charge
of _________
Polyatomic Ion
Formula
Ionic Charge
Naming Polyatomic Compounds
Rules
Examples
CaCO3
1. Write the name of the _________
2. Write the name of the _________
›
All polyatomic ions are _______ EXCEPT
____________________
Na3PO4
NH4OH
Writing Formulas for Polyatomic Compounds
Rules
Examples
1. Write the SYMBOL/FORMULA for each ion
Potassium sulfate
›
Cation (+ ion) first, then anion (- ion)
2. Put any polyatomic ions in brackets
Calcium hydroxide
3. Write the ionic CHARGES above each ion
4. CRISS-CROSS the numbers to make subscripts
Aluminum phosphate
›
DO NOT write the “+” or “-“ or the number 1
›
The subscript goes OUTSIDE the brackets.
Iron (II) sulfate
›
You CANNOT change what is inside the
brackets!!!
Lead (IV) nitrate
5. If necessary, REDUCE the subscripts to the lowest
common denominator.
6.1: Describing Chemical Reactions
Chemical Reaction

A chemical reaction occurs when

Examples:
Reactants vs. Products
Reactants
Products
Describing Chemical Reactions

Chemists use ______________________ to describe chemical reactions.

There are 2 different kinds of equations:
1. ___________ Equations: use
Example:
2. ____________________Equations: use
Example:
Symbols Used

The _____________ separates reactants and products

is read as ____________________________________________________

“____” is used to separate multiple products and/or reactants

Letter in brackets after the formula tells the ________ of the substance
(s) =
(l) =
(g) =
(aq) =
6.3 The Law of Conservation of Mass
The Law of Conservation of Mass
Examples:
→
Reactant A + Reactant B
45 g
25 g
50 g
calcium + hydrochloric acid
16 g
Product C + Product D
→
_____ g
calcium chloride + hydrogen gas
_____ g
28 g
33 g
6.4: Balancing Chemical Equations

In chemical reactions, atoms are not “magically” lost or gained, they are just ________________

This means that, in a chemical reaction, the number of atoms reacted ____________________
the number of atoms that are produced

In a chemical equation, it’s not always just _________________ of each substance that reacts or
is formed.

We need to balance chemical equations to ___________________ the NUMBER of ________
on ______________ of a reaction
Example:
Word Equation
Iron + oxygen gas → iron (II) oxide
Skeleton Equation (unbalanced)
Balanced Chemical Equation
How to balance:
Step 1: Count the number of each type of element in the reactants and products (REP table)
Step 2: Add ____________________ in front of the substances to balance the number of atoms.

** only __________ numbers can be used

** you CANNOT change _______________
Step 3: Check: are all substances balanced?
Other Tips and Rules

When balanced, simplify the coefficients (___________ them all by a common factor, if possible)

Balance any element that occurs _____________________ on one side of the
equation_________ (often H and O)

Keep polyatomic ions _________________ as a group if it remains unchanged on both sides of
the reaction
Examples: Balance the following skeleton equations:
→
1.
N2 +
H2
2.
Fe +
O2
3.
Be +
Al2O3
4.
Mg +
HNO3
5.
CH4 +
O2
→
NH3
Fe2O3
→
→
→
CO2
BeO
H2
+
+
+
Al
Mg(NO3)2
H2O
6.5, 6.6, and 6.9: Types of Chemical Reactions

Even though there are millions of possible chemical reactions that take place in nature, in industry,
and all over the world, there are only five main types (see next page).
Practice – Identify the type of reaction:
→
1. H2 + I2
2 HI
2. Mg(NO3)2 + 2 KBr
→
3. Mg(NO3)2
4. NaOH + Ca
5.
2 NH3
→
→
_________________________
→
Mg + 2
N2 + 3 H 2
8. PCl5
9. Cu
→
→
_________________________
_________________________
→
2 Li3PO4 + 3 Ca(NO3)2 _____________
3 C2H4Br2 _________________________
PCl3 + Cl2
+ 2 AgNO3
+ 2 KNO3 ___________________
NO3-
Ca(OH)2 + Na ________________________
6. Ca3(PO4)2 + 6 LiNO3
7. C2H4 + Br2
MgBr2
→
_________________________
Cu(NO3)2 + 2 Ag ____________________
Type of
Reaction
Synthesis
Decomposition
Single
Displacement
Double
Displacement
Complete
Combustion
Description
General Pattern
Examples
What to Look For
6.9: Combustion Reactions
 In general, combustion is the ________________________________ with _____________ to
produce an ________________.

Energy is produced in the form of ___________ and _______________
 _____________________ (fuel) combustion is a very common combustion reaction.

Hydrocarbons are composed of ______________ and _______________. There are
thousands of possible combinations. The general formula is CxHy
 Examples: Propane – ____________
Butane – ______________
 Hydrocarbons are used every day:
1. Complete Combustion
 There is __________________________ in the reaction, so ______ the fuel in the reaction is used
up.
 Only ______________________ and _______________are produced.
 General formula:
 Example: Burning of butane in a lighter
Characteristics:
2. Incomplete Combustion
 There is __________________________ in the reaction, so all the fuel _____________used up.
 ___________________________________ and ______________ are still produced, but so are
________________________ and _________________.
 General Formula:
 Example: Burning of butane in a lighter
Characteristics
 Flame is ____________________
 CO is a _______________________, and is _________________ and
______________________, so it is difficult to detect and can poison the air without
_____________________________

If CO gets into the body, it prevents the transport of _____________ around the body and
the person will die by _______________________ from the inside
 Carbon (C) particles are produced (____________________________)
 Many _____________________________________ are associated with incomplete combustion!
3. Other Combustion Reactions
 Other substances – besides hydrocarbons- undergo combustion reactions.
 These elements react with oxygen to form _______________
 Examples:
Combustion of Hydrogen
 Hydrogen reacts with oxygen to form water:
Completing Chemical Reactions


If you only know the reactant(s) in a reaction, you can predict what products will form!
Each type of reaction has a specific pattern. Use this to help you!
Steps to follow
1. Identify Reactant(s)
2. Identify Reaction Type
3. Predict the products using the rules for the specific reaction type
◦ If the new products are ionic, you MUST do a new “criss cross” to determine the formula of
the new compound(s)
4. Balance the Equation
1. Synthesis Reactions
(a) Metal + non-metal  Ionic compound
◦ Combine the two elements into a compound
◦ Use criss-cross rule to determine formula of new compound!
Ex:
Li
+
Cl2

Ex:
Al
+
O2

(b) non-metal + non-metal  molecular compound
◦ Simply combine the two elements into a compound, leaving the subscripts the same.
Ex:
S
+
Br2

Ex:
C
+
O2

2. Decomposition Reactions
A. Binary compounds
o Compound  element + element
o Break down into their two elements (HOFBrINCl still applies!)
Ex: H2O 
Ex: AlCl3 
B. Carbonates
o When a compound with CO3 in it decomposes, Carbon dioxide is ALWAYS formed
o The other compound is a metal oxide (compound containing the metal and oxygen)
Ex: MgCO3 
Ex: Na2CO3 
3. Single Displacement Reactions
o
o
o
The two metals switch places OR the two non-metals switch places
MUST do a new criss-cross on the new compound!! DO NOT just carry over the subscripts
If a multivalent metal exists, determine its charge from the reactant formula
Ex: Mg
+
CuCl2
Ex: KBr
+
I2
Ex: SnO2
+


Br2

4. Double Displacement Reactions
o
o
o
Switch the cations between the two compounds
Do new criss-crosses to determine new formulas!
If a multivalent metal exists, determine its charge from the reactant formula
Ex:
NaCl
Ex:
FeI3
+
BeO
+

Pb(NO3)2

5. Combustion Reactions
A. Complete
o Two products are always CO2 and H2O
Ex: Complete combustion of C6H14 (hexane – used in shoe glue)
B. Incomplete
o Four products are always CO2, H2O, CO, and C
Ex: Incomplete combustion of C8H18 (octane - car fuel)
Practice:
1.
Ag
2.
Na2S
3.
SnO
4.
HgO
5.
CaCO3
6.
Al
+
+
→
F2
+
+
Cl2
→
KCl
→
→
→
FeO
→