Elements, compounds and mixtures

Chapter 10(Chemistry)Part 1

Pure Substances• A sample of matter that has definite

chemical and physical properties.

Elements Atoms

CompoundsMolecules

Elements• pure substance that cannot be separated into

simpler substance by physical or chemical means.

Mixtures• A combination of two or more pure substances that

are not chemically combined.• substances held together by physical forces, not

chemical • No chemical change takes place • Each item retains its properties

in the mixture • They can be separated physically

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CompoundsPure substance composed of two or

more different elements joined by chemical bonds.

– Made of elements in a specific ratio that is always the same– Has a chemical formula– Can only be separated by chemical means, not physically

H2O

CO2

NaCl

Can you identify the following?

You will be shown a series of photos. Tell if each photo represents an item composed of an element, compound, or mixture.

Review:• An element contains just one type of atom. • A compound contains two or more different atoms

joined together. • A mixture contains two or more different substances

that are only physically joined together, not chemically.– A mixture can contain both elements and compounds.

Element, Compound, or Mixture?Rocks

Element, Compound, or Mixture?Rocks

Element, Compound, or Mixture?Copper

Element, Compound, or Mixture?Copper

Cu

Element, Compound, or Mixture?Jelly Beans

Element, Compound, or Mixture?Jelly Beans

Element, Compound, or Mixture?Table Sugar

Element, Compound, or Mixture?Table Sugar

C 12H 22O 11

Element, Compound, or Mixture?Diamond

Element, Compound, or Mixture?DiamondC

Element, Compound, or Mixture?Tea

Element, Compound, or Mixture?Tea

Element, Compound, or Mixture?Salt

Element, Compound, or Mixture?SaltNaCl

Element, Compound, or Mixture?Neon Gas

Element, Compound, or Mixture?Neon GasNe

Element, Compound, or Mixture?Salad

Element, Compound, or Mixture?Salad

Element, Compound, or Mixture?Pure Water

Element, Compound, or Mixture?Pure WaterH 2O

Chemical reactions and equations.- Chemists use equations to describe a chemical reaction.- The equations save time and space.- The simplest equations are word equations.

- Substances that take part in a reaction are called the reactants.- The substances formed as a result of the chemical reaction are called the

products.

- In an equation the reactants are written on the left-hand side of the equation and the products are written on the right-hand side.

- If there are two or more reactants or products in the equation they are linked together by (+) sign.

Chemical names- Chemists use equations to describe a chemical reaction.- The equations save time and space.- The simplest equations are word equations.

How are compounds named? Prefix or suffix

1st part Name of the1st elementEx. Carbon Iron Sodium

2nd part Name of 2nd element

If 2nd element is not joined to other elements Suffix -ide is usedEx. Iron + Sulphur Iron sulfide Sodium + Chlorine Sodium chloride

If the 2nd element is more that one atom Prefix di- (two) tri- (three)Ex. Carbon dioxide Sulphur dioxide

If 2 elements are joined to the 1st element 2nd name is a mixture of the 2 elementsEx. Sodium Hydroxide

If the 2nd elements is joined to oxygen atoms Suffix -ate is usedEx. Calcium carbonate Ferrous sulphate

Compound Description and uses

Calcium Oxide(Quicklime)

A white solid used to produce limelight

Carbon dioxide A colourless gas produced in respiration

Copper oxide A black pigment used to colour pottery

Sulphur dioxide A colourless gas produced when fossil fuels are burnt

Potassium hydroxide - A colourless solid used in soap making- Makes an alkaline solution used in laboratories

Calcium hydroxide - A white solid used in the treatment of sewage and drinking water.- Used to make limewater for laboratory tests

Sodium Hydroxide - A colourless liquid used in soap making- Makes an alkaline solution used in laboratories

Sodium chloride A white crystalline solid also known as common salt

Compound Description and uses

Potassium chloride A white crystalline solid used in making fertiliser

Calcium chloride - A white solid which absorbs water vapour from the air.- Used to keep materials dry.

Calcium sulfate - White solid- Used to make plaster of Paris

Copper sulphate Can form a white powder or bright blue crystals

Calcium carbonate - A white solid- A component of snail shells and egg shells

present in large amounts in limestone.

Copper carbonate A blue green solid which can form the mineral called malachite