Download Chemical changes

Atoms and Elements
Lesson 1
Objectives:
1. There are billions of materials in our
universe.
2. Those materials are made up from
about 100 elements only.
Groups
• Can you put these in some sort of order?
What is an atom?
• They are the basic building blocks of
matter.
Lets take a look deep
inside
Lets take a look deep
inside
Lets take a look deep
inside
Lets take a look deep
inside
This is a Proton.
Positive Charge
weighs ONE
Tells what type
of atom it is
GIRL
This is a Proton.
Positive Charge
weighs ONE
Tells what type
of atom it is
GIRL
This is a Proton.
Positive Charge
weighs ONE
Tells what type
of atom it is
GIRL
This is a Proton.
Positive Charge
weighs ONE
This is a Neutron No
Charge, Weighs One
NUN (does not
date)
Tells what type
of atom it is
GIRL
This is an Electron
No Weight
Negative charge
BOY
This is a Proton.
Positive Charge
weighs ONE
This is a Neutron No
Charge, Weighs ONE
NUN (does not
date)
Tells what type
of atom it is
GIRL
An element is a substance that is made
from one kind of atom only. It cannot
be broken down into simpler substances.
atom
An element
atom
An element
Molecules
• A Molecule is a
chemical in which
more than one atom
is chemically
combined. (Can be
formed from the
same or different
elements).
A compound is a substance that is made
from more than one element.
atom
A compound made up of
2 different elements
atom
A compound made up of
7 different elements
A compound can be broken down into
elements
An element
A compound made up of 3
different elements
An element
An element
Material
Made up of:
Water
Hydrogen and Oxygen
Coal
Carbon
Carbon dioxide Carbon and Oxygen
Oxygen
Oxygen
Chalk
Calcium, Carbon &
Oxygen
Wax
Carbon & Hydrogen
Table salt
Sodium & Chlorine
Caffeine
Carbon, Hydrogen,
Nitrogen & Oxygen
Element or
compound
Material
Element or compound
Water
Compound
Coal
Element
Carbon dioxide
Compound
Oxygen
Element
Chalk
Compound
Wax
Compound
Table salt
Compound
Caffeine
Compound
Physical and Chemical Change
Lesson 2
Objectives:
1. To understand the difference between
physical and chemical change and to
identify the 5 signs of chemical change
Physical changes are those
changes that do not result in the
production of a new substance. If
you melt a block of ice, you still
have H2O at the end of the
change.
If you break a bottle, you still
have glass. Painting your nails
will not stop them from being
fingernails. Some common
examples of physical changes
are: melting, freezing,
condensing, breaking, crushing,
cutting, and bending.
Some, but not all physical changes
can be reversed. You could
refreeze the water into ice, but you
cannot put your hair back together
if you don’t like your haircut!
Special types of physical changes
where any object changes state,
such as when water freezes or
evaporates, are sometimes called
change of state operations.
CHEMICAL PROPERTIES
Chemical properties can ONLY
be observed AS the substances
are changing into different
substances.
Chemical changes, or chemical
reactions, are changes that result
in the production of another
substance.
FLAMMABILITY: A material’s ability
to BURN in the presence of OXYGEN
REACTIVITY:
How readily (easily) a substance
combines chemically with other
substances.
Which has higher reactivity? A 14 karat
gold ring or a cheap metal ring from the
vending machine at the grocery store?
What is your evidence?
When you burn a log in a
fireplace, you are carrying out a
chemical reaction that releases
carbon. When you light your
Bunsen burner in lab, you are
carrying out a chemical reaction
that produces water and carbon
dioxide.
Common examples of chemical
changes that you may be
somewhat familiar with are;
digestion, respiration,
photosynthesis, burning, and
decomposition.
List 5 signs that a chemical
reaction has occurred?
• 1) Change in Odour 2) Change in Colour
3) Solid Precipitate is Formed 4) Gas
Formed 5) Release/Absorption of energy
(heat)
Physical or Chemical Change?
• Painting Wood
• PHYSICAL
Physical or Chemical Change?
• Burning Paper
• CHEMICAL
Physical or Chemical Change?
• Digestion of food
• CHEMICAL
Physical or Chemical Change?
• Sugar dissolving in
water
• PHYSICAL
Physical or Chemical Change?
• Iron turning red when
heated
• PHYSICAL
Physical or Chemical Change?
• Evaporation
• PHYSICAL
Physical or Chemical Change?
• A pond freezing in
winter
• PHYSICAL
Physical or Chemical Change?
• Melting ice
• PHYSICAL
Physical or Chemical Change?
• Cutting wire
• PHYSICAL
Physical or Chemical Change?
• Painting fingernails
• PHYSICAL
Physical or Chemical Change?
• Cutting fabric
• PHYSICAL
Physical or Chemical Change?
• Baking muffins
• CHEMICAL
Physical or Chemical Change?
• Shattering glass
• PHYSICAL
Physical or Chemical Change?
• Decomposition of old
leaves
• CHEMICAL
Physical or Chemical Change?
• Wrinkling a shirt
• PHYSICAL
Physical or Chemical Change?
• An old nail rusting
• CHEMICAL
The Periodic Table
Objective:
To learn the symbols and properties
of 20 elements in the periodic table.
The Periodic Table is a useful way to arrange elements.
The vertical columns are called groups.
The horizontal rows are called periods.
Elements in the same group have similar properties.
Three quarters of the elements are metals.
One quarter of the elements are non-metals.
Rules for chemical symbols in the periodic table:
1. The symbol is usually the first one or two letters of the
name.
2. Sometimes the old (Latin) name is used .
3. The first letter of a symbol id always a capital letter.
4. The second letter of a symbol is always a small letter.
5. Every element has a different symbol.
Now look in your periodic table and find the symbols
of the following elements, then find out if it is a
metal or a non-metal:
Copper ……..
Iron ………..
Magnesium ………..
Chlorine ………..
Carbon …………
Sodium …….
Lead ……….
Gold ………
Calcium ……..
Fluorine ……….
Now look in your periodic table and find name that
corresponds to the following symbol:
Fe ……..
Mg ………..
Ag ………..
K ………..
C …………
Ca …….
Na ……….
N ………
Ne ……..
Pb ……….
The Periodic Table
Q1. The symbol of Nitrogen is:
a. Na
b. N
Q2. Hg is the symbol of:
a. Hydrogen
b. Helium
c. Ni
c. Mercury
Q3. The percentage of metals in the periodic table is:
a. 75%
b. 50%
c. 25%
Q4. Water is not in the periodic table because:
a. It is a liquid substance
b. It is a natural substance
c. It is a compound not an element
The Periodic Table
Q1. The symbol of Nitrogen is:
a. Na
b. N
Q2. Hg is the symbol of:
a. Hydrogen
b. Helium
c. Ni
c. Mercury
Q3. The percentage of metals in the periodic table is:
a. 75%
b. 50%
c. 25%
Q4. Water is not in the periodic table because:
a. It is a liquid substance
b. It is a natural substance
c. It is a compound not an element
Q1. Name a metal in group 1 that is in the
same period as Magnesium.
Q2. Name a metal in group 2 that in the same
period as Lithium.
Q3. Name a non-metal in the same group as
Nitrogen.
Q4. Name a noble gas in the same period as
Oxygen.
Q5. Name a gas in group 7 that is in the same
period as Aluminium.
Objectives:
1. In all chemical equations the reactants
turn into products and we have an arrow
between the two as shown here:
Reactants
Products
Indicators of chemical reactions
Emission of light or heat
Formation of a gas
Formation of a precipitate
Color change
Emission of odor
All chemical reactions:
• have two parts
• Reactants - the substances you start
with
• Products- the substances you end up
with
• The reactants turn into the products.
• Reactants  Products
Symbols used in equations
•
•
•
•
(s) after the formula –solid Cu(s)
(g) after the formula –gas H2 (g)
(l) after the formula -liquid H2O(l)
(aq) after the formula - dissolved in
water, an aqueous solution. CaCl2 (aq)
 used after a product indicates a gas
(same as (g)) O2
 used after a product indicates a solid
(same as (s))
CaCo3 
The
Reaction
The thermit reaction is used by the railway
engineers to mend cracked iron rail.
It is a very useful reaction between
Aluminium and Iron oxide to produce
Aluminium oxide and Iron.
Aluminium + Iron oxide
Aluminium oxide + Iron
The reaction gives out a lot of heat,
enough heat to melt the Iron produced
which can be therefore poured into the
gaps in the rails.
Copy down the following equations in your book.
Underline the reactants and circle the
products in each of the equations:
Magnesium + Oxygen
Iron + Oxygen
Magnesium oxide
Iron oxide
1. When you react Magnesium with Oxygen you get:
a. Oxygen magnesimide
c.Magnesium oxide
b. Magnesium oxygen
d. Magnesium oxate
2. Sodium is in the same group as:
a. Magnesium b. Aluminium
c. Potassium
d. Neon
3. The colour of Magnesium oxide is:
a. White
b. Black
c. Silver
d. Brown
4. Calcium Carbonate does not contain:
a. Hydrogen
b. Oxygen
c. Carbon
d. Calcium
1. When you react Magnesium with Oxygen you get:
a. Oxygen magnesimide
c.Magnesium oxide
b. Magnesium oxygen
d. Magnesium oxate
2. One of the products of the thermit reaction is:
a. Iron oxide
b. Aluminium
c. Carbon
d. Iron
3. Sodium is in the same group as:
a. Magnesium b. Aluminium
c. Potassium
d. Neon
4. The colour of Magnesium oxide is:
a. White
b. Black
c. Silver
d. Brown
5. Calcium Carbonate does not contain:
a. Hydrogen
b. Oxygen
c. Carbon
d. Calcium
Copy down the following equations in your book.
Underline the reactants and circle the
products in each of the equations:
Magnesium + Oxygen
Calcium carbonate
Iron + Bromine
Aluminium + Chlorine
Iron + Oxygen
Lead oxide + Carbon
Magnesium oxide
Calcium Oxide + Carbon dioxide
Iron bromide
Aluminium Chloride
Iron oxide
Lead + Carbon dioxide
Law of conservation of mass
1774 Antoine Lavoisier –showed heating the red power HgO causes it to
decompose into the silvery liquid mercury and the colorless gas oxygen. 2HgO
 2Hg +O2 then show that oxygen is the key substance involved in
combustion.
Furthermore, he demonstrated by careful measurements that when
combustion is carried out in a closed container, the mass of the combustion
products is exactly equal to the mass of the starting reactants.
(tin + air+ sealed glassed vessel)  (tin oxide + remaining air + glass
vessel)
Law of conservation of mass
~ The total mass of substances present after a chemical reaction
is the same as the total mass of substances before the reaction.
Matter is neither created nor destroyed in a chemical reaction.
1. What is the name of the reaction used by
the railway engineers to mend cracked iron
rails?
2. What are the reactants of that reaction?
3.What are the products of that reaction?
Draw a line between the molecule and its name.
Hydrogen chloride HCl
Chlorine Cl2
Carbon dioxide CO2
Methane CH4
Objective:
1. Learn the scientific method for naming
compounds.
2. There are three rules for naming
compounds: the “ide” rule, the “ate” rule
and the “same” rule.
Rule 1: When two elements combine
the ending is usually ” ……………ide”.
metal goes first
Sodium Chloride
Magnesium Oxide
Iron Sulphide
Cl
Na
Mg
Fe
O
S
Rule 2: When three or more different
elements combine and one of them is
Oxygen, the ending will be “………ate”.
metal goes first
O
O
Cu
Copper Sulphate
S
O
O
Calcium Carbonate
O
Ca
C
O
O
Rule 3: When two identical elements
combine, the name does not change.
H2 = Hydrogen
F2 = Fluorine
H
F
F
N
N2 = Nitrogen
Cl2 = Chlorine
O2 = Oxygen
H
Cl
O
N
Cl
O
Name the following compound
Na2O
Name the following compound
CuSO4
Name the following compound
MgSO4
Name the following compound
ZnO
Name the following compound
MgCl2
Name the following molecule
H2
Name the following compound
KI
Name the following compound
AgNO3
Fill in the blanks:
Magnesium + …………….
……………….. + Iodine
……………. + Oxygen
Copper oxide + Carbon
Magnesium oxide
Hydrogen …………..
Iron oxide
………….. + Carbon dioxide
Chemical Reactions
Objectives:
1. The formula of a compound shows the
number and the type of atoms in it.
2. A small number after the symbol for each
element in a compound shows how many
atoms each molecule contain.
Draw a line between the compound and its name:
Magnesium Carbonate
MgCl2
Zinc Fluoride
NaCl
Magnesium Chloride
Pb(NO3)2
Iron sulphide
FeS
Lead nitrate
CaCO3
Copper sulphate
CuSO4
Potassium Iodide
ZnF2
Sodium Chloride
MgCO3
Calcium Carbonate
KI
1. How many atoms of Hydrogen in one molecule of
Methane CH4 ?
2. How many atoms of Nitrogen in one molecule of
Lead nitrate Pb(NO3)2 ?
3. Sodium oxide has two atoms of sodium for every
atom of oxygen. What is the formula for sodium
oxide?
4. Magnesium chloride has one atom of Magnesium
for every two atoms of chlorine. What is the
formula for Magnesium chloride?
5. How many atoms of Nitrogen in one molecule of
Ammonia NH3 ?
1. How many atoms of Oxygen is there is two
molecules of CuSO4 ?
a. 1
b. 4
c. 6
d. 8
2. Oxygen will:
• turn limewater milk
b. relight a glowing splint
c. burn with a squeaky pop d. put out a glowing splint
3. How many atoms are there altogether in one
molecule of MgCl2 ?
• 2
b. 3
c. 4
d. 6
Chemical Reactions
Objectives:
1. The number of atoms in the reactants are
equal to the number of atoms in the
products.
Mg + 2 HCl
MgCl2 + H2
What are the reactants of the above reaction?
What are the products?
Mg + 2 HCl
MgCl2 + H2
Give me your
Chlorine and get
out of here.
Mg
H
H
Cl
Cl
Mg + CuO
MgO + Cu
Give me your
Oxygen and get
out of here.
Oxygen
Mg
Cu
Thermal Decomposition
Objective: Compounds can be broken
down into smaller substances using
heat.
Test for gases
Draw a line between the name of the gas and the
method to test for it.
Carbon dioxide
Oxygen
Hydrogen
relights a
glowing splint
burns with a
squeaky pop
turns limewater
cloudy
Investigating whether a mystery
substance is an element or a
compound.
mystery substance
compound
element
metal
?
non-metal
What do you think the mystery
substance is ???
…………………..
thermal
decomposition
CuO + CO2