Atoms, Elements, Molecules, Compounds Matter Atoms, Elements, Molecules, Compounds

Matter Matter is the “stuff” that all objects and substances in the universe are made of. Because all matter takes up space (has volume) and contains a certain amount of material (has mass), all matter can be detected and measured.

You can observe some types of matter easily with your senses. You can see and feel things like rocks, trees, bicycles, and different kinds of animals. You can also see and smell things like smoke and fire.

Matter Other types of matter are harder to detect. They can be observed by using a microscope. Another example of matter that is hard to detect if air, the invisible gas that surrounds you. You can’t see or smell it, but you know it exists. You can feel it when the wind blows and see it bend the branches of trees. Regardless of what kind of matter you have, all matter is made up of a combination of different elements from the periodic table.

How many different substances are there? can you think of? There are millions of different substances! What are they all made of?

All substances are made of atoms All substances are made of very tiny particles called atoms. Many substances are made up of different types of atoms. hydrogen and oxygen atoms carbon and hydrogen atoms iron, aluminium, silicon, oxygen and boron atoms carbon, nitrogen, hydrogen, oxygen and sulphur atoms

What is an element? carbon helium copper All substances are made of very tiny particles called atoms. There are about one hundred substances that are made up of just one type of atom. These are the elements. carbon helium copper The elements are the simplest substances in the universe. The elements are the building blocks of all other substances.

Atoms in elements An element is a substance made up of only one type of atom. Copper is an element made up of copper atoms only. Carbon is an element made up of carbon atoms only. Helium is an element made up of helium atoms only.

Atoms and molecules of elements Contents An element is a substance made up of only one type of atom. In some elements, the atoms are joined in groups of two or more. A particle containing atoms grouped in this way is called a molecule. Oxygen is an element made up of oxygen atoms only. How many atoms are there in an oxygen molecule? Other elements, that contain atoms joined in molecules are hydrogen, nitrogen, chlorine and bromine.

Introducing chemical symbols A standard set of symbols is used to represent elements: The symbol for many of the more common elements uses just the first letter of the name. hydrogen H = oxygen O = carbon C = nitrogen N = fluorine F = iodine I = Others elements have the first two letters. Some of the symbols are not always as you might expect. lithium Li = lead Pb = aluminium Al = gold Au = helium He = silver Ag =

How to write symbols for elements Two important rules should be followed when writing the symbols of elements so that there is no confusion. 1. The first letter of an element’s symbol is always a capital letter. e.g. N (not n) for nitrogen 2. If there are two letters in the element’s symbol, the second letter is always a small letter. e.g. Co (not CO) for cobalt No, Watson! It was carbon monoxide poisoning – not cobalt.

Symbols for molecules of elements In some elements, the atoms are joined together and form molecules. Combining the symbols of the atoms in a molecule gives you the formula of the molecule. What is the formula for the molecules in each element? O2 oxygen There are groups of two atoms in each molecule. H 2 hydrogen N2 nitrogen

Metals and non-metals in the periodic table The periodic table is a list of all the known elements which are arranged according to the similarities in their properties. Metals are on the left and in the centre. Non-metals are mostly on the right. Xe What type of elements are between metals and non-metals?

Combining elements How is possible to have so many different materials from a limited number of elements?

Combining elements How do you get so many different cheeses? What is the key ingredient in all cheeses? Milk is combined with a small number of ingredients under different conditions to make a huge number of different cheeses. In a similar way, a small number of elements can be combined in many different ways to make a huge number of different compounds.

A compound is always made up of two or more different types of atom. What is a compound? A compound is the substance produced when two or more elements combine in a chemical reaction. Two elements, hydrogen (H) and oxygen (O), combine to make the compound, water. Which two elements combine to make the compound carbon dioxide? A compound is always made up of two or more different types of atom.

Making a compound – carbon dioxide A compound has very different properties to the elements from which it is made. elements compound carbon A black solid which can be used as a fuel. oxygen A colourless gas which is essential for life. carbon dioxide A colourless gas which is used to put out fires. combines with to make

Making a compound – water What are the elements which make up water? In what ways are the elements different to their compound? elements compound hydrogen A colourless gas which is used in hot air balloons. A colourless gas which is essential for life. oxygen water A liquid which is essential to our lives and has many different uses. combines with to make

Element or compound?

Element or compound?

Atoms joining in a chemical reaction When the two elements, hydrogen and oxygen, combine in a chemical reaction, the hydrogen and oxygen atoms do not just mix together they become joined to one another. hydrogen oxygen water + H O + H In a chemical reaction, the atoms in the reactants become joined in different ways and this is how new substances are formed.

Glossary atom – The smallest particle that can exist on its own. compound – Substance made up of two or more different elements that are chemically joined together. element – Substance made up of only one type of atom. formula – The symbols and numbers that represent the atoms in a substance. molecule – Two or more atoms that are chemically joined together. periodic table – Table in which all known elements are arranged based on their properties. symbol – One or two letters that represent an element.