Embed Size (px)
Citation preview
28/11/2014
1
COMPOUNDS FORM ACCORDING
TO A SET OF RULES.
Unit B: Matter and Chemical Change
Section 3.0
Scie
nce
9 - U
nit B
- Sectio
n 3
1
3.1 NAMING COMPOUNDS
Every compound has a chemical name and a
chemical formula: from the shampoo in your
bathroom to the gasoline in your garage.
2
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
2
LEARNING OUTCOMES
Key Concepts
periodic table
elements, compounds, and atomic theory
chemical nomenclature
Learning Outcomes
distinguish between ionic and molecular compounds, and describe the
properties of some common examples of each
read and interpret chemical formulas for compounds of two
elements, and give the IUPAC name and common name of these
compounds
identify/describe chemicals commonly found in the home, and
write the chemical symbols
identify examples of combining ratios/number of atoms per molecule found
in some common materials, and use information on ion charges to predict
combining ratios in ionic compounds of two elements
assemble or draw simple models of molecular and ionic
compounds^
3
Scie
nce
9 - U
nit B
- Sectio
n 3
*CHEMICAL FORMULA*
Combination of symbols that represent a
compound
The formula identifies:
the elements in the compound, and
the amount of each element
Example:
The chemical formula for salt is NaCl
Scie
nce
9 - U
nit B
- Sectio
n 3
4
28/11/2014
3
EXAMPLE: ETHANOL
C2H5OH
Scie
nce
9 - U
nit B
- Sectio
n 3
5
NAMING CHEMICAL COMPOUNDS
Until the 18th century, no standardized system
existed for naming chemicals. This created
confusion because the names for chemical
compounds varied from country to country and
scientist to scientist.
Example:
hydrochloric acid and muriatic acid refer to the same
thing.
6
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
4
NAMING CHEMICAL COMPOUNDS (CONTINUED)
In 1787, a French chemist
named Guyton de Morveau
created a naming system, or
nomenclature, for compounds.
He decided to use the chemical
name for each element in the
compound, always putting the
metal element first.
7
Scie
nce
9 - U
nit B
- Sectio
n 3
IUPAC
Since 1920, the International Union of Pure
and Applied Chemistry (IUPAC) has been
responsible for determining the appropriate
name for each compound.
They are also looked to when there are
discrepancies in spelling.
Example:
Aluminium vs Aluminum
Sulphur vs Sulfur
8
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
5
CHEMICAL NAMES AND FORMULAS
If you know the formula for a compound, you will
be able to determine its chemical name.
If you know the name of a compound, you will be
able to determine its formula.
Chemical name Chemical formula
9
Scie
nce
9 - U
nit B
- Sectio
n 3
-IDE SUFFIX
You will notice that some compounds
have a chemical name where the name
ends in “-ide”
We’ll learn later when to write names
using -ide. For now, just look at the
first part of the second word to help
you figure out which element it
represents. Example: sodium chloride
10
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
6
INTERPRETING CHEMICAL
NAMES AND FORMULAS
What is the chemical formula for water?
H2O
Notice that next to the H is a small “2” as a subscript.
(“Sub” means below.)
The 2 indicates that there are two atoms of hydrogen
to go with every atom of oxygen in water.
11
Scie
nce
9 - U
nit B
- Sectio
n 3
INTERPRETING CHEMICAL
NAMES AND FORMULAS (CONTINUED)
No subscript number indicates that only one
atom of that element is needed.
12
Scie
nce
9 - U
nit B
- Sectio
n 3
1
28/11/2014
7
Compound Chemical
Formula
Elements # of Atoms of
Each
Total # of
Atoms
Water
EXAMPLE: WATER
Fill in the following chart for water.
13
Scie
nce
9 - U
nit B
- Sectio
n 3
Compound
(Chemical
name)
Chemical
Formula
Elements # of Atoms of
Each
Total # of
Atoms
EXAMPLE: TABLE SALT
Fill in the following chart for table salt.
14
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
8
Table salt’s chemical name, sodium chloride, is
a compound made of one atom of sodium and
one atom of chlorine
MODELS OF ATOMS
15
Scie
nce
9 - U
nit B
- Sectio
n 3
What would the model for water look like?
MODELS OF ATOMS (CONTINUED)
16
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
9
PHYSICAL STATE OF A COMPOUND
Indicating the state of the chemical at room
temperature is another common notation.
Recall: solid (s) Ex: NaCl(s)
liquid (l ) H2O(l)
gas (g) O2(g)
17
Scie
nce
9 - U
nit B
- Sectio
n 3
AQUEOUS SOLUTIONS
Recall that aqueous solutions are substances
dissolved in water.
A subscript “aq” in parentheses is added to the
formula (aqueous comes from the Greek word
“aqua” which means water).
Example: sodium chloride dissolved in water
would be written as NaCl(aq).
18
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
10
- SKILL PRACTICE PG. 142
- C & R PG. 143 # 3, 4
Assignment
19
S
cien
ce 9
- Un
it B - S
ectio
n 3
SKILL PRACTICE; PG. 142
Compound Elements in
Compound
# of Atoms in
Each Element
Drawing of
Compound
20
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
11
C & R PG. 143 # 3, 4
21
Scie
nce
9 - U
nit B
- Sectio
n 3
C & R PG. 143 # 3, 4
22
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
12
C&R #4D - CHEMICAL NAME &
PHYSICAL STATE : GLUCOSE - SOLID
Chemical Formula : C6H12O6 (s)
The chemical formula for glucose tells us that
each molecule is made of 6 carbon atoms, 12
hydrogen atoms, and 6 oxygen atoms.
Atomic model
Scie
nce
9 - U
nit B
- Sectio
n 3
23
TOPIC 3.2:
IONIC COMPOUNDS
Textbook: pg 144 – 147
24
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
13
LEARNING OUTCOMES
Key Concepts
periodic table
elements, compounds, and atomic theory
chemical nomenclature
Learning Outcomes
distinguish between ionic and molecular compounds, and describe the properties of some common examples of each
read and interpret chemical formulas for compounds of two elements, and give the IUPAC name and common name of these compounds
identify/describe chemicals commonly found in the home, and write the chemical symbols
identify examples of combining ratios/number of atoms per molecule found in some common materials, and use information on ion charges to predict combining ratios in ionic compounds of two elements
assemble or draw simple models of molecular and ionic compounds 25
Scie
nce
9 - U
nit B
- Sectio
n 3
*IONIC COMPOUND*
pure substances formed as a result of the
attraction between particles of opposite charges,
called ions
Ionic compound = metal + non-metal
26
+ — Ionic
compound
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
14
*IONS*
An ion is an atom that has
become electrically charged
because it has lost or gained
electrons;
a positive ion is an atom that has
lost one or more electrons;
a negative ion is an atom that has
gained one or more electrons
^When an ionic compound is dissolved in
water, the metal and non-metal form an
aqueous solution of ions.^
27
e-
e-
e-
e-
Scie
nce
9 - U
nit B
- Sectio
n 3
ION CHARGES
28
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
15
IONIC COMPOUND
29
Ionic
Ions
Charges + -
Scie
nce
9 - U
nit B
- Sectio
n 3
POLYATOMIC IONS
A group of atoms acting as one
^“Poly” means “many.”^
Example:
carbonate ion (limestone): CO32-
sulfate ion: SO42-
30
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
16
EXCEPTION!
If the non-metal ion (-) is a polyatomic ion, the
name remains unchanged.
Example: CaCO3 Ca2+ and CO32-
31
Scie
nce
9 - U
nit B
- Sectio
n 3
PROPERTIES OF IONIC COMPOUNDS
Attraction between particles of opposite charges
(ions)
High melting points
Good electrical conductors (when melted or
dissolved)
Distinct crystal shape
Solids at room temperature
Example: Table Salt melts at 801°C.
32
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
17
^ALL IONIC COMPOUNDS MODEL
DIFFERENT CRYSTAL SHAPES.^
^Naturally occurring elements are made of atoms of different sizes and properties that combine in many ways to form crystals. The huge range of temperatures and pressures within the Earth contributes to this diversity.^
33
Scie
nce
9 - U
nit B
- Sectio
n 3
CRYSTAL
34
When ions combine, they form a crystal.
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
18
ION CHARGES
An ionic charge is written as a superscript and is (+) or
(–) with a number to indicate how many electrons were
added or taken away.
35
Textbook pg. 146
Scie
nce
9 - U
nit B
- Sectio
n 3
36
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
19
^RECALL: IONIC COMPOUNDS
metal + non-metal
Positively charged ions + negatively-charged ions^
37
+ - +
Scie
nce
9 - U
nit B
- Sectio
n 3
EX: SODIUM CHLORIDE IS AN
IONIC COMPOUND.
Chemical formula: NaCl
Common name: table salt
Chemical name: sodium chloride
^When the compound is dissolved in water, the
metal and non-metal form an aqueous solution of
ions.^ 38
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
20
NAMING IONIC COMPOUNDS
Example: NaCl(s)
1. Write the chemical name of the metal (+) ion
first.
NaCl(s) metal = Na = sodium
2. Write the chemical name of the non-metal (-)
ion, but change its ending to -ide.
NaCl(s) non-metal = Cl = chlorine
We write chloride instead of chlorine
Our answer: NaCl(s) = sodium chloride
39
Scie
nce
9 - U
nit B
- Sectio
n 3
ALWAYS AN EXCEPTION...
There is one exception to these naming rules.
Where negative ions are polyatomic ions, the
name remains unchanged.
Example:
Limestone’s chemical name remains calcium
carbonate.
40
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
21
Some elements with more than one
ion charge use a roman numeral
written in brackets in its chemical
name to clearly show which ion is being
used.
Copper(II) Sulfate
Copper(I) Sulfate
Scie
nce
9 - U
nit B
- Sectio
n 3
41
NAMING COMPOUNDS
42
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
22
USING ION CHARGES & CHEMICAL
NAMES TO WRITE FORMULAS:
Step 1: Print the metal element’s name, symbol
and ion charge, and the non-metal’s name,
symbol and ion charge. Example: Calcium chloride
Metal: Calcium Ca2+
Non-metal: Chlorine Cl1-
Scie
nce
9 - U
nit B
- Sectio
n 3
43
Step 2: Balance the ion charges (^the positive ion must
balance with the negative ion^)
We have:
Ca 2+ = Cl 1-
We Need:
Ca 2+ = Cl 1- + Cl 1-
Scie
nce
9 - U
nit B
- Sectio
n 3
44
28/11/2014
23
Step 3: Write the formula by indicating how many
atoms of each element are in it.
CaCl2
Scie
nce
9 - U
nit B
- Sectio
n 3
45
^ANOTHER WAY TO BALANCE THE IONS^
In step 2, you can also balance the ions using the
following method:
1. Write the ions with their charges.
2. Write the charge as a subscript at the opposite ion,
without the (+) or (-) sign.
3. If an ion has a subscript of 1, you don’t have to
write it down. Simplify the ratio, if possible.
Example: calcium chloride
Ca 2+ Cl 1-
Ca Cl 2
46
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
24
YOUR TURN!
Write the chemical formula for aluminum
oxide.
47
Scie
nce
9 - U
nit B
- Sectio
n 3
^OXYANIONS (polyatomic anions containing
oxygen) are named with
–ite or –ate, for a lesser or greater quantity of
oxygen.^
Nitrite NO2-
Nitrate NO3-
Scie
nce
9 - U
nit B
- Sectio
n 3
48
28/11/2014
25
^OTHER POLYATOMIC IONS:^
^Nitrate NO3 1-^
^Nitrite NO2 1-^
^Carbonate CO3 2-
^
^Sulfate SO4 2-
^
^Hydroxide OH 1- ^
^Cyanide CN 1- ^
^Ammonium NH4 1+ ^
Scie
nce
9 - U
nit B
- Sectio
n 3
49
^POLY-ATOMIC (MANY ATOMS) IONS^
^Ex: Nitrite
NO2 is a polyatomic ion.^
Let’s see what the chemical formula is
for Calcium Nitrite. (pesticide)
2+ = Ca 1- = NO2
Together it forms
Ca(NO2) 2
Scie
nce
9 - U
nit B
- Sectio
n 3
50
28/11/2014
26
TRY TO MAKE CALCIUM CARBONATE
IF…
CO3 2- is carbonate.
Calcium carbonate is also known as
limestone.
= Ca CO3
Scie
nce
9 - U
nit B
- Sectio
n 3
51
^LOOKING BACK…^
^How many of each element was there?^
Al2O3 NaCl Ca(NO2) 2
H2O NO2
Scie
nce
9 - U
nit B
- Sectio
n 3
52
28/11/2014
27
ASSIGNMENT
C&R page 149 #7-8
53
Chemical
formula
for the
compound
Elements
in each
compound
Number of
atoms in
each
element
Name of
“metal” (+)
ion and
the charge
Name of
“non-
metal” (-)
ion with –
ide and
the charge
Name of
compound
sodium
fluoride
LiCl(s)
Scie
nce
9 - U
nit B
- Sectio
n 3
TOPIC 3.3: MOLECULAR
COMPOUNDS Textbook pg. 150 - 153 54
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
28
LEARNING OUTCOMES
Key Concepts
periodic table
elements, compounds, and atomic theory
chemical nomenclature
Learning Outcomes
distinguish between ionic and molecular compounds, and describe the properties of some common examples of each
read and interpret chemical formulas for compounds of two elements, and give the IUPAC name and common name of these compounds
identify/describe chemicals commonly found in the home, and write the chemical symbols
identify examples of combining ratios/number of atoms per molecule found in some common materials, and use information on ion charges to predict combining ratios in ionic compounds of two elements
assemble or draw simple models of molecular and ionic compounds 55
Scie
nce
9 - U
nit B
- Sectio
n 3
MOLECULAR COMPOUNDS
When non-metals combine, a pure substance
called a molecule or a molecular compound is
formed.
You can think of atoms that have bonded
together.
56
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
29
LOOKING BACK…
Which chemicals are IONIC,
and which are MOLECULAR?
Al2O3 NaCl Ca(NO2)2 H2O
NO2
Scie
nce
9 - U
nit B
- Sectio
n 3
57
They can be solids, liquids, or gases at room
temperature.
They tend to be good insulators, or poor conductors of
electricity.
They also have relatively low melting and boiling
points because the forces between the molecules are
weak.
Examples:
sugar, acetylene, and water.
58
PROPERTIES OF MOLECULAR COMPOUNDS
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
30
^MOLECULAR COMPOUNDS INCLUDE:^
^DNA^
e
e
e
e 59
Scie
nce
9 - U
nit B
- Sectio
n 3
EXAMPLES:
Sugar (sucrose) – sweetener, preservative
C12H22O11
Glucose - energy source for living things
C6H12O6
Acetylene (ethyne) – making chemicals
C2H2
Scie
nce
9 - U
nit B
- Sectio
n 3
60
28/11/2014
31
^SUGAR CRYSTAL^
^The top picture
looks like salt
crystals, but if you
take a closer look,
you will see that
SUGAR crystals
are
HEXAGONAL.^
Scie
nce
9 - U
nit B
- Sectio
n 3
61
Scie
nce
9 - U
nit B
- Sectio
n 3
62
28/11/2014
32
WRITING FORMULAS FOR MOLECULAR
COMPOUNDS
*The ion charge is not used in the formulas
of molecular compounds.*
^Writing formulas for molecular compounds is
similar to writing formulas for ionic compounds,
except that no ions are present and the ion
charge is not used in the formulas. This makes it
hard to predict how non-metals combine.
The chemical formula still tells us how many of
each type of atom is present in the molecule.
63
Scie
nce
9 - U
nit B
- Sectio
n 3
EXAMPLES OF MOLECULAR
COMPOUNDS
Scie
nce
9 - U
nit B
- Sectio
n 3
64
28/11/2014
33
NAMING OF MOLECULAR COMPOUNDS
All molecular compounds
can be named using the
following rules, except
those containing
hydrogen.
Common names are used
for molecular compounds
containing hydrogen.
65
Scie
nce
9 - U
nit B
- Sectio
n 3
PREFIX RULES
66
Recall: suffix –adds on to the end
prefix –adds on the
front
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
34
NAMING OF MOLECULAR COMPOUNDS (CONTINUED)
1. The first element in the compound uses the element name—just like ionic compounds.
2. The second element in the compound has the suffix ‘ide’—just like ionic compounds.
3. A prefix is used to specify the number of atoms of each element in the compound.
4. An exception to rule 3 is when the first element has only one atom, the prefix mono is not used.
Example: N2O
N2O N = ___________
67
Scie
nce
9 - U
nit B
- Sectio
n 3
NAMING OF MOLECULAR COMPOUNDS (CONTINUED)
1. The first element in the compound uses the element name—just like ionic compounds.
2. The second element in the compound has the suffix ‘ide’—just like ionic compounds.
3. A prefix is used to specify the number of atoms of each element in the compound.
4. An exception to rule 3 is when the first element has only one atom, the prefix mono is not used.
Example: CO2 is read as carbon dioxide, not monocarbon dioxide.
Example: N2O
N2O N = nitrogen
N2O O = oxygen Oxygen “oxide”
68
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
35
NAMING OF MOLECULAR COMPOUNDS (CONTINUED)
1. The first element in the compound uses the element name—just like ionic compounds.
2. The second element in the compound has the suffix ‘ide’—just like ionic compounds.
3. A prefix is used to specify the number of atoms of each element in the compound.
4. An exception to rule 3 is when the first element has only one atom, the prefix mono is not used.
Example: N2O
N2O N = nitrogen
N2O O = oxygen Oxygen “oxide”
2 N’s di dinitrogen
1 O mono Monoxide
N2O has a chemical name of dinitrogen monoxide.
69
Scie
nce
9 - U
nit B
- Sectio
n 3
NAMING OF MOLECULAR COMPOUNDS (CONTINUED)
1. The first element in the compound uses the element name—just like ionic compounds.
2. The second element in the compound has the suffix ‘ide’—just like ionic compounds.
3. A prefix is used to specify the number of atoms of each element in the compound.
4. An exception to rule 3 is when the first element has only one atom, the prefix mono is not used.
Example: CO
Monocarbon monoxide
CO has a chemical name of carbon monoxide.
70
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
36
NAMING OF MOLECULAR COMPOUNDS (CONTINUED)
Scie
nce
9 - U
nit B
- Sectio
n 3
71
IONIC VS. MOLECULAR COMPOUNDS
Ionic Compounds Molecular Compounds
Relatively high
melting and boiling
points
Solids at room
temperature
Good conductors of
electricity
Distinct crystal shape
Examples:
Relatively low melting
and boiling points
Solids, liquids, or
gases at room
temperature
Poor conductors of
electricity (they make
good insulators)
Examples:
72
Scie
nce
9 - U
nit B
- Sectio
n 3
28/11/2014
37
HOMEWORK S
cien
ce 9
- Un
it B - S
ectio
n 3
73
Check and Reflect
pg. 153 #1-6
