ATOMS AND ELEMENTS

 Before starting this unit, you should already be familiar with these ideas from earlier work.

• Matter is all the material in the Universe. Everything  we know rocks, air,water, plants, animals andeven humans is made of matter. Matter can  exst in three states as a solid, as a liquid and a gas.
   
• If we cannot see and touch something in science, we can use a model to help show us how it works. What model have you used to represent circuits?

• The particle model suggests that all matter is made up of particles. How are the particles arranged in a solids, liquids and gases?
• Matter sometimes changes state from solid to liquid or liquid to gas and back again. Boiling is one change of state. List some others.
• All matter is made up of  tiny particles called atoms.
  material that is made of only one type of atom is called an element.
  
  
   Elements are found naturally on Earth and in space although some have been created in laboratories in recent times. 
• The elements were not all discovered at once, and some are very recent discoveries.
   

ATOMS

All matter is composed of atoms.

Atoms are the smallest pieces of a substance that can exist.

Atoms are very, very tiny. You cannot see atoms, not even with a microscope.

Scientist have done many experiments to find out about atoms.

They use the results of their experiments to develop theories or models to help us understand what atoms are like and how the behave.

At the centre of the atom there is a core called the nucleus .

The nucleus is made up of sub-atomic atoms (smaller than atoms)  called protons and neutrons.

All around the core is an area of spinning electrons.

They remain in place because  they are attracted to the opposite charge of the protons and the neutrons.

The protons have a positive charge and neutrons have no electric charge

Hydrogen atoms are the only atoms without neutrons

A normal atom has the same number of protons as electrons.

The atomic number of an atom tell you how many proton it has.

         Atomic             Number of          Number of

        Number     =     Protons      =      Electrons

 

Electrons are much smaller than protons, they weigh almost nothiing.

The atomic mass of an atom depends on the number of protons and neutrons in the nucleus

Carbon has an atomic mass of twelve.

The number of protons and neutrons is called the mass number of atoms.

Mass Number (A)   =   Atomic          +        Number of

                                      Number(z)              Neutrons