Atomic Theory

The ancient Greeks developed an atomic theory. In those days, science and philosophy were one and the same. The idea of the existence of atoms was arrived at through philosophy or 'thought experiments'. If you have a pure block of copper and cut it in half and then in half again, again and again ... and so on, you will eventually arrive at the smallest 'bit' of copper that is still recognisably copper. This was called an atom of copper. This was then extrapolated to be true for all the elements. Atomic theory was born!

The theory has made rather drastic progress since those days and is highly complex. An atomic is vastly smaller than anything that we can see in everyday life -if the point of a pin is approximately 0.1mm in diameter, this makes it about 1 million atoms wide! This means that an atom something that is very difficult to envisage.

One of the amazing things that was discovered about the atom is that it mainly consists of empty space:

Theory today says that an atom is made up of three main components:

It is important to bear in mind that this is a very simplistic model of the atom and that it is all much more interesting than this!!

Most of the mass of the atom is concentrated in the nucleus which is very, very small. This results in the nucleus of an atom being massive but tiny!

The negative electrons are held in place by the electrostatic attraction of the positive nucleus.

Contents

Safety, Static Electricity
Charge
Current Electricity, Making a bulb light, Models
Conductors and insulators
Switches, Short circuits, Circuit diagrams
Current, Voltage
Electrical circuits
Measuring current
Resistance
Power
Assessment/Discussion Material
Reference Material