S1 Chemistry Notes

St. Ninian’s High School

Atoms Everything in the world is either a solid, a liquid, or a gas. Scientists say that solids, liquids and gases are the three states of matter.

Solids

Bricks are solid. They do not change their shape. Their volume is also fixed.

We say that these are the properties of a solid.

Solids have fixed shapes and volumes.

Liquids

Water is a liquid. Liquids can flow. When we pour water from a test tube into the beaker, the water flows and changes its shape to fit the shape of the beaker. If we pour 50 cm3 of water from the test tube we expect that the beaker will contain 50 cm3 of water. Liquids change their shape but have a fixed volume.

Gas

Air is a gas. Gases can flow. When we pour water from a test tube into a beaker, the gas flows and changes its shape to fit the shape of the beaker. Unlike liquids the gas can also change its volume. Gases can change their shape and their volume.

Atoms

Scientists explain the properties of solids, liquids, and gases by talking about at-oms. Atoms are like small balls. They are so small that if we placed 1,000,000,000 atoms end to end the line would be about 1 metre long.

We think that the atoms in a solid are packed closely together. The atoms do not move. This explains why solids have a constant shape and volume.

In a liquid we believe that the atoms are still closely packed together, but that they are free to flow. This explains why liquids can change their shape but cannot change their volume.

Gases are more complex. The atoms can move freely in three dimensions. They are only held together by the container the gas is kept in. The atoms are constantly moving, colliding with the walls of the container.

This explains why gases have a variable shape and volume.

Gases are easily compressed because of the large spaces between their particles.

Solids, like the concrete this bridge is made from do not compress easily because their particles are close together.

S1 Chemistry Notes

St. Ninian’s High School

Melting and Boiling

When ice at 0oC is heated the temperature of the ice does not change. The heat energy is used to change the solid particles in free moving liquid particles. When we melt a substance the temperature does not change, the substance simply changes from a solid to a liquid.

In a similar way, when water at 100oC is heated the temperature does not in-crease, the water at 100oC turns into steam at 100oC.

When we melt or boil a substance we do not increase the temperature, the added energy simply increases the particles’ freedom to move.

The Water Cycle.

The diagram below shows the names given to the changes when water, ice, and steam change from one state of matter to another.

These changes all happen in nature. The way in which water circulates in nature is called the water cycle.

The diagram below shows the water cycle.

Ice Melts 00C

Water Boils 1000C

Particles in a solid Particles in a liquid

If you put the wrong things down the sink, such as cooking oil and dairy products it blocks the water cycle, cost-ing us all money!

Likewise with the toilet.

S1 Chemistry Notes

St. Ninian’s High School

Solutions

If some salt is added to water and the mixture shaken the salt disappears.

We say that the salt has dissolved in the water, to make a solution.

Substances which dissolve are said to be soluble. Substances which do not dissolve are said to be insoluble.

Solvent, solute, Solution

Sugar dissolves in water. The liquid which does the dissolving, the water, is called the solvent.

The substance which is dissolved, the sugar, is called the solute.

The mixture, the sugary water, is the solution.

A saturated solution.

Sea water is a solution of salt in

water.

One litre of water contains 20

grams of salt. This is a saturated solution of salt in water.

Solutions everywhere!

Many things are solutions, Irn Bru contains fla-vourings, colourings and carbon dioxide which are all dissolved in water.

The Irn Bru is a solution.

The water is the solvent.

The flavourings, colourings and carbon dioxide are the solutes.

Making a solution

Salty water solution

Coffee is a complex solution, which

contains among other chemicals, the

drug caffeine

Sea water contains a large amount of

dissolved salt—it is a solution.

Sugary water solution—Sugar dissolves, it is soluble.

Water

Sugar

Irn Bru is a solution that we drink.

S1 Chemistry Notes

St. Ninian’s High School

Separating things In chemistry it is important to be able to separate one substance from another.

We can see an example of this type of separation in the production of sugar from sugar cane.

Sugar cane is a bamboo like plant which grows well in hot countries. The cane contains about 10% sugar mixed with many other things. Pure sugar can be obtained by using three chemical techniques

1. Dissolving

2. Filtration

3. Evaporation

Filtration

Filtration is a simple way of removing an insoluble substance from water. The mix-ture is poured through a filter paper.

Insoluble substances are trapped in the filter paper, water and other dissolved substances pass through the paper into the beaker.

Evaporation

Evaporation is a simple way of separating a dissolved substance from water. The mixture is placed in an evaporating basin and heated.

The water boils and turns into steam leaving the dissolved solid in the basin.

Rock salt

Rock salt is a mixture of sand and salt which is ob-tained from mines, the sand and salt can be sepa-rated by.

1. Adding water, the salt dissolves, the sand does not.

2. Filtering, this removes the insoluble sand from the salt solution.

3. Evaporating the salt solution, this removes the water and leaves the salt.

Purified cane sugar

Sea salt is made by evaporating sea water to leave the salt be-hind.

S1 Chemistry Notes

St. Ninian’s High School

Chemical Elements

Elements and the Periodic Table

Everything in the world is made up of substances called elements. There are about 100 different elements in the world. The elements are listed in the periodic table of the elements.

Each element has a name and a symbol. Hydrogen is the lightest of all the elements

and has the symbol H. The next lightest element is Helium which has the symbol He.

Hydrogen is the simplest and smallest atom of any element. It is given an atomic number of 1.

Helium is the next simplest element, it is given the atomic number 2.

Most elements are made of much more complicated atoms.

Carbon, an element found in all living things has an atomic number of 6, and has the symbol C.

As you can see the atoms of different elements are different from each other. But atoms of the same element are the same as each other.

Modern computers use element No. 14—Silicon

Many thermometers used to record high temperatures contain element No. 80—Mercury, which is a liquid.

Mendeleev, a Russian

chemist who made the first periodic ta-ble in 1867.

An atom of Hydrogen

An atom of Helium

An atom of Carbon

S1 Chemistry Notes

St. Ninian’s High School

Compounds Making compounds

When a piece of magnesium is held in tongs and heated in a Bunsen flame it burns brightly to form a white powder. This powder is a compound of magnesi-um and oxygen. The two elements have joined to make a new substance called magnesium oxide.

The space shuttle gets its power by burning hydrogen with oxygen.

The hydrogen and oxygen react together to form a compound called hydrogen oxide- this is the chemi-cal name for water. The clouds of ‘smoke’ seen when the shuttle launches are in fact clouds of steam.

Naming Compounds

The name of a compound tells us the elements present in the compound. Rust has the chemical name Iron oxide. It contains the elements iron and oxygen.

The ‘stinky’gas which comes from bad

eggs is called hydrogen sulfide.

The name tells us that it contains

hydrogen and sulfur.

The bubbles in beer contain the gas carbon dioxide- a compound of carbon and oxy-gen. The Di part of the name tells us that there are two atoms of

oxygen for every atom of carbon.

Heating magnesium changes it into mag-nesium oxide.

Launching the space shuttle.

As cars get older iron changes into iron oxide—rust.

Carbon dioxide bubbles in a pint of beer.

Salt is Sodium Chlo-ride - a compound made of Sodium and Chlorine.

Water is Hydrogen Oxide, a compound made of hydrogen and oxygen.

Aspirin is a very com-plicated chemical which contains only 3 elements.

S1 Chemistry Notes

St. Ninian’s High School

Complex Compounds Until now we have only looked at compounds made from two elements. More complicated compounds exist. Any compound whose name ends in ate contains oxygen. e.g.

Potassium sulfate contains potassium, sulfur, and oxygen.

Sodium carbonate contains sodium, carbon, and oxygen.

Aluminium nitrate contains aluminium, nitrogen, and oxygen.

Similarly the ending -ite also tells us that a compound contains oxygen. e.g.

Sodium nitrite contains the elements sodium, nitrogen, and oxygen.

Word equations Carbon & oxygen

Charcoal is used as a fuel for barbecues. Charcoal contains the element Carbon which is a good fuel. When the charcoal is heated the carbon in it begins to react with the oxygen in the air. The carbon and oxygen are Reactants.

When the carbon and oxygen react

together they make carbon dioxide.

Carbon dioxide is the product of the re-action. We show this reaction as a

word equation:

Carbon + Oxygen ---> Carbon dioxide

Hydrogen & oxygen

Many elements react with oxygen. Most space rockets use hydrogen as a fuel.

In the photograph on the left you can see a space shuttle launch. The large, dark coloured tank attached to the shuttle contains hydrogen and oxygen. These two chemicals react together. They are the reactants. When they react together they make water, Water is the product.

The word equation for this reaction is:

Hydrogen + Oxygen —> Water

Fertilisers contain

potassium nitrate- a compound containing potassium, nitrogen and oxygen.

Barbecuing—chemical reactions in action.

Lighters contain pro-pane gas which reacts with oxygen and pro-duces energy.

Carbon reacting with oxygen to help cook chicken.

Hydrogen reacting with oxygen to power the space shuttle.

S1 Chemistry Notes

St. Ninian’s High School

Compounds & Formulae Water

Water has the chemical name hydrogen oxide. This tells us that it contains hydrogen and oxygen.

The diagram on the right shows how the hydrogen and oxygen join. This is a molecule of water.

Because the molecule contains 2 atoms of hydrogen joined to one atom of oxygen it has the chemical formula H2O.

Ammonia

Ammonia is a gas which contains the elements nitrogen and hydrogen.

In a molecule of ammonia there are 3 atoms of hydrogen and one atom of nitrogen.

Ammonia has the formula NH3.

Vinegar

Vinegar contains the chemical ethanoic acid. A molecule of ethanoic acid contains 2 atoms of carbon, 4 atoms of hydrogen, and 2 atoms of

oxygen. It has the chemical formula C2H4O2.

Butane

On the left is a model of a molecule

of a gas called butane, which is a hydrocarbon. Bu-tane is used as a fuel in gas barbecues.

The molecule contains 4 atoms of carbon and 10 atoms of hydrogen.

Butane has the formula C4H10.

A molecule of caf-feine, the drug in cof-fee and tea. Caffeine contains the elements carbon, hydrogen, & oxygen.

A molecule of benzene - a hydrocarbon pre-sent in petrol.

A molecule of water, chemi-cal formula H2O.

A molecule of ammonia,

chemical formula NH3.

A molecule of ammonia,

chemical formula NH3.

A molecule of ammonia,

chemical formula NH3.

Vinegar is used to fla-vour foods, such as chips.

S1 Chemistry Notes

St. Ninian’s High School

Chemical reactions Changes

Eggs contain various chemicals, proteins, fats, minerals, and vitamins, as well as water.

When the egg is heated these chemicals

change, we say that a chemical reaction

has occurred.

The cooked egg is solid, it is very different from the uncooked egg.

In chemical reactions new substances are formed. These new substances can look very different from the original substances.

Energy changes

Many chemical reactions involve energy changes. An example is the reaction which powers the

space shuttle.

The rocket motors of the shuttle react hydrogen and oxygen together. When the hydrogen and oxygen react together they produce steam and a large amount of heat.

The ‘smoke’ at a shuttle launch is clouds of steam.

This is another exothermic reaction- a reaction where chemical energy changes into heat energy.

Electrolysis

The two elements, copper and chlorine react togeth-er to form the compound copper chloride. This process can be reversed. The compound copper chloride can be broken down into the elements copper and chlorine.

To do this the copper chloride is dissolved in water and electricity passed through the solution.

The process is called electrolysis.

When you toast bread a chemical reaction oc-curs.

A chemical reaction is used to change milk into cheese.

Space shuttle at take off.

After the reaction!

A mixture of chemicals!

S1 Chemistry Notes

St. Ninian’s High School

Carbon Cycle Most of the chemicals that make up living tissue contain carbon. When organisms die the carbon is recycled. The model that de-scribes this process is called the carbon cycle.

Carbon dioxide is a greenhouse gas, this means it traps heat in the earth’s atmosphere.

The carbon cycle is closely linked to the greenhouse effect— dead organisms are eaten by other or-ganisms and the carbon in their bodies is returned to the atmos-phere as carbon dioxide.

In some conditions decomposition doesn't happen. The plant and animal material may then be available as fossil fuel in the future for combustion. Carbon enters the atmosphere as carbon dioxide from respiration and combustion.

The more combustion that occurs, the more carbon dioxide enters the atmosphere, and the earth heats up more as a results.

Rocks Naturally occurring elements and compounds are called minerals. These are present in the Earth’s crust. At present there are over 3000 minerals, 300 are common enough to have uses to us. These materials come from different rock and soil types across the earth.

Igneous Rock

Igneous, from Latin, means fire or heat. These rocks are made by molten rock deep within the Earth which then cools. Extrusive rock is formed when the molten rock is

cooled quickly on Earth’s surface, these have fine crystals. Intrusive rock is formed when the molten rock cools slowly (thousands/ millions of years) deep within the Earth’s crust. These have large crystals.

Sedimentary Rock

Sedimentary rock is made from rocks that have been erod-ed. The eroded rock is called sediments and flows in rivers and other moving water. The sediment flows, settles and is then squeezed into solid rock. You can often see fossils in

sedimentary rock.

Metamorphic Rock

Meta, from Greek means after, and morph, from Greek means to form or shape. Sedimentary rocks are made from rocks that have been changed into something new by heat and pressure. Igneous and Sedimentary rock can both un-dergo this change.

A pumice stone is an example of an extrusive rock.

A sedimentary rock face

A Marble statue in the bo-tanical gardens, Glasgow

The carbon cycle has remained steady for thousands of years.

Granite is used for worktops in kitchens—it is an extrusive rock.

Marble can also be used for flooring.

The burning of fossil fuels for power pro-duces large quantities of carbon dioxide.

Glasgow’s famous ten-ements are built using sandstone—a sedimen-tary rock.

S1 Chemistry Notes

St. Ninian’s High School

I should be able to:

State that there are three states of matter; solids, liquids, and gases.

State that solids have a constant shape and volume.

State that liquids can change their shape to fit the container they are in, but that liquids cannot change their volume.

State that gases can change their shape and volume to fit the container they are in.

State that all things in the world are made of tiny

particles called atoms

State that the atoms in a solid are:

1. tightly packed together with very little space between atoms

2. arranged in a neat and regular way

3. not able to move freely

State that the atoms in a liquid are:

1. tightly packed together with very little space between atoms

2. free to move about within the liquid

State that in a gas:

1. atoms can move around freely in all directions

2. there are large spaces between all the atoms

State that melting is the change from a solid to a liquid

State that freezing is the change from a liquid to a solid.

State that evaporation is the change from a liquid to a gas.

State that condensation is the change from a gas to a liquid.

State that water freezes and ice melts at 0°C.

State that water boils and steam condenses at 100°C.

Identify the changes which happen in the water cycle as being evaporation, condensation, melting and freezing.

State that a substance which dissolves in water is said to be soluble.

State that a substance which does not dissolve in water is said to be insoluble.

State that when salt dissolves in water to make salty water, the solid which dissolves, the salt, is called a solute the liquid which does the dissolving, the water, is called the solvent. The liquid produced ( salty water) is called the solution.

State that a liquid in which no more solid will dissolve is called a saturated solution.

State that if a warm, saturated solution is left to cool, crystals of the solute are produced.

State that filtration is used to remove an insoluble solid from water.

State that soluble substances can be recovered from a solution by evaporation.

State that a mixture of salt and sand can be separated by:

1. Adding water to dissolve the salt

2. Filtering to remove the sand

3. Evaporating to remove the water and leave the salt

behind

State that everything in the world is made of small particles called Atoms.

State that there are about 100 substances called elements which are not mixtures. All of the atoms in an element are the same.

State that the atoms in different elements are not the same.

State that all of the elements are arranged in a chart called the periodic table.

S1 Chemistry Notes

St. Ninian’s High School

When elements join together in a chemical reaction they form compounds.

When chemical reactions occur new substances are made.

You should be able, given the name of a compound, to work out the elements present in the compound.

Compounds whose names end in -ate contain oxygen

Breaking up compounds into it’s elements using elec-tricity is called electrolysis.

Many chemical reactions involve an energy change and that for most reactions the energy change is Chemical Energy ---> Heat energy.

A reaction in which

Chemical Energy ---> Heat energy is called an exother-mic reaction

You should be able to write a word equation for a chemical reaction.

You should know that a word equation is made up of four things—reactants, products, plus signs and an ar-row.

A group of atoms held together by chemical bonds is called a molecule.

The molecular formula of a compound shows the num-ber of atoms of each element in the compound

Know that carbon is recycled when organisms die

Know that carbon dioxide and methane are greenhouse gases

Know that without greenhouse gases earth couldn't support life

Know that increasing the quantity of greenhouse gases in the atmosphere to much will heat the earth up irre-versibly

Know that burning fossil fuels releases large quantities of carbon dioxide into the air

Know that there are three types of rock:

1. Igneous

2. Metamorphic

3. Sedimentary

You should be able to describe the processes by which the three types of rock are formed

Know different uses for the different types of rock

Know that ores and minerals can be extracted from the rocks and used to make items such as light bulbs and glass.