Atoms Elements and Compounds

Atoms and Elements Everything is made up of tiny particles called atoms Atoms are tiny the tiniest speck you can see contains millions of atoms! Molecular Expressions: Science, Optics and You - Secret Worlds: The Universe Within - Interactive Java Tutorial

Elements When a substance is made of only 1 type of atom it is called an element For example Copper is only made of Copper atoms it can’t be broken into anything simpler

The periodic Table of elements This is a table of all the types of elements found on earth Anything that exists is either one of these elements or a mixture of them! Element Song Do you recognise any of these elements?

Definitions An atom is the smallest part of an element that still has the properties of that element An Element is a substance that cannot be broken down into simpler substances by chemical means

Some common elements Carbon – A solid that can have 2 forms, grey graphite or pencil “lead” or the gemstone Diamond! It is not a metal

Sulfur - a yellow solid non metal, it makes matches and gunpowder

ery Iron – A hard silvery grey solid metallic element it is very common and is used to make ships, cars, skyscrapers etc.

Silver – a bright grey solid metal used to make jewellery and ornaments

Gold – A heavy, precious yellow metallic element, used for jewellry

Sodium – A soft, silver white metallic element that is very reactive Sodium – A soft, silver white metallic element that is very reactive! It is used in street lighting as it glows yellow when burned

Symbols of Elements Each element has its own chemical symbol, usually it is the initial of the element eg, H for Hydrogen, but sometimes the symbols come from Latin eg. Na for Sodium The first letter is always a capital The second letter if there is one is always a small letter

Compounds There are only about 100 elements but we know there are hundreds of thousands of other substances such a s salt, water, plastic, carbon dioxide , sand etc. These substances are made of 1 or more elements chemically combined together Water is H2O this means Hydrogen and Oxygen chemically combined together

Definition A compound is made when two or more elements combine together chemically

Making a compound If we burn 2 elements such as iron and sulphur together we can get a completely new substance called Iron Sulphide Look at the properties of iron and sulphur before they are chemically combined

If the iron and sulphur are mixed together the iron can be separated using a magnet When they are chemically combined the iron is no longer magnetic! A compound is a completely new substance with its own properties

Think of Water Water is made of Hydrogen which is an explosive gas and oxygen which is needed to burn things yet when they combine to form H2O you get a liquid that can put out fires!

Molecules A compound is made up of molecules 1 H2O is a molecule of water Carbon Dioxide gas is CO2 what type of atoms are in a molecule of Carbon Dioxide? Answer

Big Molecules Some molecules are very big and contain lots of atoms A molecule of sugar is C12H22O11 This means that 1 molecule of sugar has 12 carbons, 22 hydrogens and 11 oxygens!

Small Molecules Some molecules are very small Hydrogen gas is made of H2 molecules which is 2 hydrogen atoms

Definition A molecule is the smallest part of an element or compound that can exist on its own

Fixed amounts The atoms that make a compound are present in definite fixed amounts For example water will always have 2 hydrogens and one oxygen in a molecule Salt NaCl will always have one sodium and one Chlorine in a molecule