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Grade 9 Science: Chemistry Unit

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Chapter #1: Matter

Properties of Matter
You have seen how matter can have different physical properties with the example of the metal and the glass. These are both “solids” but they had very different properties, in that one could bend the other just broke. These different properties are known as physical properties.
- A physical property is a characteristic or description of a substance that may help to identify it, eg colour
- The States of Matter is the physical property of matter at room temperature (200 c) whether it is solid, liquid or gas

The Following are Properties of Matter
- Hardness: is the measure of the resistance of a solid to being scratched or dented eg diamond is very hard
- Malleability: means that it can be hammered or bent into different shapes eg gold (Au) is very malleable
- Ductility: Means it is able to be drawn into long thin wires eg copper (Cu)
-Melting and Boiling Points: The temp. at which substances change state are characteristic physical properties
- Crystal Form: is the solid forms of many minerals in which you can see definite structure of cubes or blocks with a regular pattern
- Solubility: is the ability of a substance to dissolve in a solvent such as water eg salt (NaCl) in water (H2O)
- Viscosity: refers to how easily a liquid flows, the thicker the liquid the more viscous it is, viscosity is always in relationship to water
- Density: is the amount of matter per unit volume of that matter
- Chemical property: describes the behavior of a substance as it becomes a new substance (eg wood burning) a chemical change is characterized as being something very difficult to reverse
- Combustibility: a property that describes the ability of a substance to react with oxygen (O2) to produce carbon dioxide (CO2), water (H2O) and energy
- Reaction with Acid: Certain substances when added to an acid will dissolve and release a gas eg Magnesium (Mg) and HCl
Pg 19 # 1 - 4

Physical and Chemical Changes
- Some of the most powerful properties of matter is how and why it changes
- Matter change can be broken into two different categories: Physical and Chemical changes

Physical Changes
- The substance remains the same even though it may change state or form
- Examples of change of state (physical change): melting, boiling, freezing, condensation, sublimation
- Dissolving is also a change of state, when you dissolve a substance in water it is still that substance just the particles are spread out
- Most physical changes are easily reversed (you are able to retrieve the starting materials in the states that they existed originally)

Chemical Changes
- The original substance is changed into one or more different substances that have different properties
- Chemical changes always involve the creation of new substances and most are hard to reverse
- Examples of a chemical change has occurred: energy is released (often in the form of heat released or absorbed, or light is given off), gas is formed (bubbles seen), a solid material forms from a liquid ( this is called a precipitate), the change is difficult to reverse, and colour change is noted (this is a very poor example as colour change happens easily and very often is not a chemical change, this should be used as your last argument for chemical change)
Homework: Pg 30#1-4

- Corrosion: is the slow chemical change that occurs when a metal reacts with O2 to form a new substance called an oxide
Kind of Corrosion
- Rusting is the reaction of Fe with O2 to from and Iron Oxide
- The rusting of steel (which is a polymer of Fe, C and other substances) is actually the interaction of Fe with O2 and is accelerated by water and salts
- Simple rust is the cause of billions of dollars of damage yearly
- Rust absorbs water like a sponge, as a result is dissolves or flakes off leaving a fresh layer of steel to be attacked
- Al does not rust because when it reacts O2 it creates aluminium oxide which is strong and unaffected by H2O, this oxide then stays and acts as a protective coating (this protective coating is the substance you may see on your Al cooking utensils)

Preventing Corrosion
- Painting the surface of the metal: if the metal is coated by a paint so that no air can get at it, then it will not rust
- Cathodic protection: some metals rust easier then does Fe, these metals (eg Zn) rust away first (almost like they attract the rust) this leaves the valuable metal and you can just change these Zn strips
- Special Alloys: this steel is a mixture of metals with Ni and copper oxides mixed in, the metals corrode quickly leaving the Ni and copper oxides to form a protective layer which stop all future rusting
- Plastics and other material: as our understanding of polymers is increasing our ability to make them very strong is also taking place, this allows us to create very strong plastics which will not rust (these plastics can be found on car bumpers)
Page35 # 1 - 6

- Combustion is the rapid reaction of substance with O2 and releases energy
- For a fire to burn it needs all three conditions: heat, O2, and fuel. If any one of these items are missing then the fire will not burn (coldness will put a fire out)

Fossil Fuels and Combustion
- Coal, oil, natural gas, and gasoline are all examples of fossil fuels
- Fossil fuels get this name because they were once plants and/or animals and when these organisms died they did not decompose completely, instead they were buried by sediments and the energy in their cells remained “locked up”
- The stored energy in these cells is what fuels our society and is a trillion dollar industry annually
- When a fossil fuel burns the main products are CO2 (carbon dioxide) and H2O vapour, the particles that make up fossil fuels are called hydrocarbons
- The following word equation can be used to represent the burning of fossil fuels:
hydrocarbons + O2 - CO2 + H2O

- When looking at a chemical formula (and you will see a lot of these in the next couple of weeks and years) the starting materials are always written on the left hand side and the product is written on the right hand side of the arrow
- Starting materials are called reactants and final product are called products
- If you see arrows that look like the ⇄ this means that the reaction has the ability to go forward and back just as easily

Combustion and Air Pollution
- Under ideal conditions the combustion of hydrocarbons produces only CO2 and H2O
- ideal conditions rarely (never happen in the environment)
- When there is not enough oxygen present then the combustion will start to produce CO (carbon monoxide) and C
-When car engine burns it releases CO2 which increases the greenhouse effect
- Combustion of hydrocarbons also releases trace elements of CO, sulphur dioxide, and nitrogen oxides all of which are harmful to the environment and humans
- Combustion of fossil fuels is the leading cause of air pollution in the world

Questions: pg. 39 #1-5
Chapter 1 Review: pg 40 # 1 - 16

Chapter #2: Elements and Compounds

Models of Matter: The Particle Theory
- Matter has been determined to be anything that takes up space and has a mass
- Democritus over 2000 years ago stated that all things were made up of small particles - the building block of matter

Pure Substances and Mixtures
- Using the particle theory we can understand 2 categories of substances: pure and mixtures
- Pure Substance: this contains only one kind of particle eg Al foil only has Al in it
- Mixture: contains at least 2 different pure substances or different types of particles

Classifying Mixtures
- Mixtures can be categorized into two different categories: solution and heterogenous mixtures
- Solution: may be made up of solid, liquids or gases
- Solution exist in a homogenous combination (can not easily see or extract the substances from each other) eg perfume is a solution as it is a combination of alcohol and fragrances
- Heterogenous mixtures: each part of the mixture can easily be seen and separated from one another eg garden soil, salad dressing, etc.

Elements and Compounds
- Elements: are pure substances that cannot be broken down into simpler substances, elements are made up of protons, neutrons and electrons. It is the number of protons, neutrons and electrons in an element that give it the properties that are unique to every element
- Compounds: are pure substances that contain two or more different elements in a fixed proportion

Atoms and Elements
- Each element is one kind of atom, these atoms make up all substances
- Water is an eg of a fixed proportional substance. Water is always going to be H2O, this means that for every atom of oxygen there is going to be 2 hydrogen atoms so when you are measuring the volume of water you will always get twice as much hydrogen as you will oxygen

- Molecules: contain two atoms or many thousands of atoms, these atoms can be different or all the same typ of atoms
- Pure molecule Eg in oxygen there are 2 O atoms in each molecule
- Butane is an Eg of a molecule that is not all pure substance, butane is a molecule that has 4 C and 10 H which is written as C4H10

Different Molecules from the Same Elements
- In compounds atoms of one element join together in a fixed ratio with atom of other elements
- Eg is the combination of H and O, if these two atoms join in the ratio 2:1 then you will get H2O, but they also join readily in the ratios 1:1 and 3:1 this is the two different ionic states of water OH- and H3O+, O and H can also join in the ratio 2:2, what is this substance?
- The difference of these substances is huge, water make up large quantities of the human body were if hydrogen peroxide (H2O2) and blood mix there is an instant reaction very similar to the one you saw when the acid interacted with the baking soda
Questions: pg 47# 1 - 4

Putting Metals to Work
- Elements can be broken into two categories: metals and non-metals
- Metals: are all elements that exist on the left hand side of the thick red line on the periodic table (these bond using ionic bonds)
- Non-metals: are all elements that exist on the right hand side of the thick red line (these produce bond using covalent bonds)
- The number and of electrons, protons and neutrons and the distribution of electrons gives these metals many different attributes, eg. The ability to conduct heat or electricity, also the ductility, strength and hardness are also effected by these numbers

Metals and Industry
- The many different properties of metal can make them very appealing to industry
- Some examples:
- Pt: Very nice for jewelry, very unreactive, but is an excellent conductor of electricity
- U: Is extremely dense and hard, out side of being used in nuclear power plants they are also used in Canon shells (this is the expected cause of Gulf War Syndrome, a un-talked about disease/ disorder found in Gulf War Vets.)
- Mg: A light, strong metal that can be used in automobile wheels and luggage
- In small doses heavy metals are essential for healthy plants and animals, however in large quantities these can cause damage
- Not only can heavy metals be absorbed through eating them but they can be absorbed through breathing them in from the air or by drinking them in H2O (if you look at the ingredients of water on a bottle of water, you will see the amount of heavy metals in your water)
Pg 51 #1 - 3

Chemical Substances and Formulas
- Names given to elements differ all over the world because they have different languages but all countries and languages use the symbol for an element
- In China were the predominate language is Mandarin, the periodic table still looks the same, so even though Carbon is not spelt like Carbon it is still represented by a C on their periodic table
- This hold true for all formulas as well, as butane would still be C4H10 even though it may not be called butane

Some Review Stuff
- Elements/ atoms make everything
- Elements usually exist as molecules (more then one element) this could be different elements or the same elements
- The number seen in a chemical equation (C4H10) tells you that in this substance there is 4 Carbon atoms and 10 hydrogen atoms
- Atoms are made up of Protons, Electron and Neutrons
Pg.59 # 1 - 5

Atoms, Molecules, and the Atmosphere
- With every breath you take you are inhaling billions of molecules, most of which are N2 and O2

Nitrogen (N2)
- N gas exists as N2, which makes up 80% of the air that we breath
- This is a very stable molecule so that it does not react when we breath it, nor does it react to things in and around in the environment
- Under certain conditions, like those found in a cars engine, N2 and O2 come together to form NO2 a very toxic red-brown gas
- NO2 is the cause of the yellow haze of air pollution you may see in some cities

- Argon is part of the noble gases, these are the gases that exist on the far right hand side of the periodic table
- For the most part these gases are very unreactive, which is why they are called noble gases
- Ar is an example of an atom that does not form molecules, instead it hangs out by itself as a loner (like me on a Friday night) this is because it is happy as a single element and actually does not have the ability to bond
- Ar is used in for flourescent lights

Oxygen, O2 and O3 (very important stuff)
- O can combine and form two very different molecules O2 and O3
- O2 makes up roughly 21% of the air that we breathe and is what we refer to commonly as O2 gas
- O3 is the less common form of oxygen but is just as important, O3 is known as ozone and contains three O
- O3 forms naturally in the atmosphere and is very important to life on earth because it absorbs most of the ultraviolet radiation from the sun
- O3 is what we are destroying with our pollution especially chlorofluorocarbons (CFC’s) CCl2F2
- Though O3 is important in the atmosphere, at ground level it is very poisonous because it reacts with peoples lung tissue

Carbon Dioxide (CO2) and Carbon Monoxide (CO)
- These are the only two molecules that exists as gasses and contain both carbon and oxygen elements
- CO2 is important to life on earth and CO is very poisonous to most life forms
- As discussed, the burning of fossil fuels in abundance of O2 under perfect conditions creates only CO2 and H2O, but if there is not enough O2 then CO will be produced
- CO is a similar molecule to O2 therefore when it enters your lunges and is carried through your blood stream as if it were O2, this deprives the body of O2 leading to death
- This is why CO detectors are becoming such common thing in peoples houses
Questions #1-4 on pg. 61

At this point we started to look at Bohr-Rutherford diagrams and this lead tp Covalent and Ionic bonds. This is very important stuff make sure that you understand it.

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