Test Review PowerPoint for
nd
2 Period
Conservation of Mass
• You must end up with the same amount you started with.
• Mass cannot be created or destroyed
Conservation of Mass
• Matter is not created or destroyed
Balancing Equations
 Goal- Have the same number of atoms on both sides of the
equation.
 Rules
◦ Coefficients (numbers in front) multiply
◦ You can not change subscripts (numbers behind)
◦ If there is no subscript after an atom, then you know there is only 1 atom
present
Balancing Equations
1. Write equation
2. Count Atoms
H
O
H
O
2
2
2
1
Balancing Equations
H
2
O
2
2
H
2
O
4
1
2
3. Use coefficients to balance the equation
H
O
H
O
42
2
4
2
Balancing Equations Practice
•
2
H2 + O2  H2O
2
2
•
H2 + Cl2  HCl
•
SO2 + 2 O2  SO3
2
•
Mg + 2 O2  MgO
2
Reactants and Products
Reactants are combined together
to create products
What are the reactants and products in the following
equations?
C + 2O
Reactants
COProduct
2H + O
2
H2O
Products
Reactant
What do you notice about these equations?
Coefficients-big numbers (in front)
Subscripts-small numbers (behind)
Chemical Equations
• Label the reactants and products on the chemical equation below:
• CaCO3
Reactants
CaO + CO2
Products
Label the reactants and products.
On the practice worksheet.
• Mg + O2
• 2H2O2
• 2Cu2O + C
• FeS + 2HCl
• P4O10 + 6H2O
• Fe2O3 + C
• SO2 + O2
MgO
2 H2O + O2
4Cu + CO2
FeCl2 + H2S
4H3PO4
Fe + CO2
SO3
How do we make the reaction go faster?
• There are four things that we can change to make the
reaction go faster.
• They are
• Temperature
• Surface area
• Concentration
• Using a catalyst
1. Temperature
• When we increase the temperature we give the
particles energy
• This makes them move faster
• This means they collide with other particles
more often
• So the reaction goes faster.
2. Surface area
• If we make the pieces of the
reactants smaller we increase the
number of particles on the
surface which can react.
• This makes the reaction faster.
The particles
on the surface
can react
When cut into
smaller pieces
the particles on
the inside can
react
3. Concentration
• If we make one reactant
more concentrated,
there are more particles
in the same volume to
react
• So the reaction goes
faster.
There are less red
particles in the same
volume so there is
less chance of a
collision
There are more red
particles in the same
volume so there is
more chance of a
collision so the
reaction goes faster
http://www.youtube.com/watch?feature=player_embedded&v=kjKyEdrVXJA
4. Using a catalyst
• A catalyst is a chemical which is added to a reaction.
• It makes the reaction go faster.
• The catalyst does not get used up in the reaction.
• It gives the reaction the energy to get started
Enzyme catalyst
http://www.youtube.com/watch?v=XX9Xo6zm_kM&feature=player_detailpage
Atoms
• Modern Atom Model
• Nucleus-Protons and Neutrons
• Electrons around nucleus, never know the true location
Protons
• Positively charged particle
• In nucleus
• Mass 1 amu
Neutrons
• Neutral (no) charge particle
• In nucleus
• Mass 1 amu
Electrons
• Negatively charged particle
• In electron cloud (orbitals) around the nucleus
• Mass 0 amu
Elements
• Made of atoms of one kind
• The type of element depends on the atomic number, or the number
of protons it has
• Most elements occur naturally, but some have to be created in a lab
Periodic Table
• Elements are organized on the Periodic Table
according to atomic number and properties of the
element
Open textbook to pages L14 – L15
Symbol
• The abbreviation letters used for each element
Atomic Number
• Number of protons (each element has a different # of protons)
• Number of electrons (same as # of protons so the element is
electrically neutral)
Atomic Mass
• Mass of the Atom or # of the protons plus neutrons
• Each proton equals 1 amu and each neutron equals 1
amu (atomic mass unit)
How do you find the average number of neutrons in an atom?
atomic mass ( rounded) – atomic number
Groups
• Groups: or Family = columns
• Share similar properties
• Numbers on top indicate what group it is
• Noble gases-Group 18 (or 8A)
• Halogens-Group 17 (or 7A)
• Alkali metals-Group 1
Periods
• Periods = rows
• Atomic mass increases from left to right
• Number of protons increases from left to right
• Number of electrons in the outer shell of the atom increases from left
to right
• Only hydrogen and helium are in the 1st period
Look at L14 –15 or L186 – L187