Transcript Science 9 Unit 2

Science 9
Unit 2
Chemistry
Properties of Matter
Matter is anything that has mass and occupies
space.
Matter can be identified by its physical properties
(melting point, density, colour and state)
Matter can also be identified by its chemical
properties (how a substance reacts with others.
Ways to Describe or classify matter:
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State (solid, liquid or gas)
Solubility (do they mix well)
Luster ( are they dull or shiny)
Density
Lesson 921
Matter
Mixture
Solution/ Homogeneous
Mixture eg. Apple juice
Appear as one usually clear
Pure Substance
Mechanical Mixture
Heterogeneous
e.g sand and gravel
Element
One Atom
E.g.. Oxygen
Compounds
Two or more atoms
E.g.. Water
Colloids
Liquid in liquid
Milk, mayo, jelly
Ordinary Mech. Mixture
Lg parts can see them
Stay mixed
Suspensions
Lg.particles evenly
Mixed but settle
Emulsions
Quickly separate to form layers
Types of Matter
Pure Substance
– Material that contains one kind of particle
– Either an element or compound
Mixture
– Combination of two or more pure substances
such that each one’s properties are not lost
but may be hidden
Types of Mixtures
Homogeneous mixture (solution)
– Particles are uniformly scattered; has a uniform
composition
– Usually clear and cannot be separated by filtering
– Eg. Apple juice
Heterogeneous mixture (mechanical)
– Particles are not uniformly scattered and not a
uniform composition.
– Can see the parts
– Can be filtered and separated
Heterogeneous Mixtures
Heterogeneous mixtures is a mechanical mixture where
you can see the parts
There are three types of heterogeneous mixtures based
on the size of the particles.
Ordinary mechanical mixtures have parts big enough
to see and they stay mixed. E.g. granite
Suspensions are large mixed particles but separate if
left or by filtering. E.g. liquid medications
Colloids are fine particles evenly distributed through a
second substance. E.g. hair gel and clouds.
Emulsions are a type of colloid that are liquids in liquids.
E.g. Milk, Mayonnaise, Jell-O
Changes in Matter
Physical Change
Change in form/ change from solid,
liquid or gas
Always reversible!
The composition doesn’t change
Water is water even if frozen or
condensed
E.G. Ice changing to water (melting)
Chemical Change
One kind of matter is changed to a
different kind of matter
E.G. Iron changing to rust with the
addition of oxygen.
Identifiers:
Color change
Gas bubbles
Temp. change (heat absorbed or
produced)
Irreversible
Form a precipitate (solid)
Starting material used up
A new material formed
Chemical Reactions & Law of
Conservation of Mass
Substances that go into a chemical reaction are the
reactants and the products
During a chemical reaction the reactants are used up
During a chemical reaction the products are created or
produced
Law of conservation of mass states that in a chemical
change the total mass of the new substance is the same
as the total mass of the original.
Mass of reactants = Mass of products
Therefore 2H2 + O2  H2O
Types of Chemical Reactions
2 Types of Chemical Reactions
Endothermic – where energy is absorbed eg. Alkaseltzer and water
Exothermic- where energy is released e.g. an explosion or fire eg.
Burning log
Oxidation reactions are common in nature
– Some reactions are slow; others are fast
– Eg. Corrosion -Corrosion is the oxidation of metals or rocks in the
presence of air and moisture This is an endothermic reaction.
E.g. Iron + O2 rust
– Combustion- Combustion is an exothermic combination of a substance
with oxygen. This requires heat, oxygen and fuel e.g. a barbeque
Chemical reactions are represented by word or symbol equations
– Eg. Magnesium + Hydrochloric Acid  Magnesium chloride & Hydrogen
gas
– E.g. Mg + 2HCl  MgCl2 + H2 (g)
Factors Affecting The Rate
of Chemical Reactions
Heat – the more heat added the faster the
reaction. E.g. burning dinner
Concentration – the higher the concentration of
reactants the faster the reaction
Surface area – the more surface area the faster
the reaction. E.g. a sugar cube takes longer to
dissolve than regular refined sugar
Energy – the type of energy used will determine
how fast the reaction occurs. E.g. if you use
electrical energy from a battery the reaction will
be faster
Atomic Structure
Dalton’s Atomic Theory- review from text
– Matter is made of atoms
– Atoms can’t be created or destroyed
– All atoms of the same element are the same
size and weight.
Atoms are composed of subatomic
particles
– Protons, electrons and neutrons
– Each of which have their own characteristics.
Subatomic Particles
Protons
– Have + charge
– Large size
– Found in the nucleus of an atom
Electrons
– Have negative (-) charge
– Small (very sm. Compared t the proton)
– Found in the orbit or energy level of the atom
Neutrons
– Have no charge
– Large in size (same size as proton)
– Found in the nucleus of an atom
Atomic Number
The atomic number of an atom is the
number of protons found in the nucleus
and also represents the no. of electrons
found in the orbits
The Atomic Mass Unit is the total mass of
the protons and neutrons in the nucleus
Periodic Table review
Elements are grouped based on physical and chemical properties (melting
point, color, density, state and reactivity)
Metals on left side
Non-metals on right side
Metalloids on “staircase”
Noble gases on extreme right side (unreactive, and stable)
Horizontal rows called periods
– All atoms in a period have the same no. of energy levels
Vertical columns called groups or families
– All atoms in a group have the same chemical characteristics
Each box on the table contains specific info. About each element (pg.440441 in text)
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Atomic number
Ions
Symbol
Name
Atomic mass unit
Quiz Info
Memorize the symbols and names of all
elements from 1-30. Also, include iron,
copper, zinc, silver,tin,lead,mercury and
gold
Quiz will include everything else we
covered today.