Electrons and Protons

Electrons are the smallest and lightest of the fundamental particles. They are said to have a negative charge, meaning that they are surrounded by some kind of an invisible field of force that will react in an electrically negative manner with other matter. Protons are said to have a positive charge and they are surrounded by an invisible force field that causes them to react in an electrically positive manner.

The words negative and positive are just names to describe the so-called charge of electrons and protons, and their charge describes how they interact with each other. We could just as easily call the charge of the electron the white charge and the charge of the proton the black charge. My point is, ‘charge’ is an electric behaviour and since there are two types of charge we need to name them so that when we talk about them we will know which behaviour we are speaking off: either the positive charge behaviour, or the negative charge behaviour.

AN EXPERIMENT WITH CHARGE
You may have already done this, if you have please try it again. Tear up some tiny strips of paper and place them on the table in front of you. Make sure no one is watching! Now run a hair comb through your hair briskly several times and place the comb close to the bits of paper. Before, the comb touches the paper, a bit of paper will leap off the table and move through the air and cling to the comb. This happens because you have produced a charge on the comb, which will physically interact with matter around it (in our case the bit of paper). The charge on the comb was created by friction between the comb and your hair.

Protons are about eighteen hundred times as massive as electrons and have a positive electric field surrounding them. The proton is exactly as positive as the electron is negative; each has a unit electric charge. When an electron and a proton are far apart, only a few of their lines of force (the invisible field around them) join and pull together. The attracting pull between the two charges is therefore small. When brought closer together, the electron and proton are able to link more of their lines of force and will pull together with greater force.

If close enough, all the lines of force from the electron are joined to all the lines of force of the proton and there is no external field, and they attract each other strongly. Together, a positive charge proton and the negative charge of an electron cancel out and they form a neutral, or uncharged, group. The neutral atomic particle, known as a neutron, exists in the nucleus of all atoms heavier than hydrogen.

The fact that electrons repel other electrons, protons repel other protons, but electrons and protons attract each other gives us the basic law of charges:

Like charges repel, unlike charges attract.

Because the proton is about 1,800 times heavier than the electron, it seems reasonable to assume that when an electron and a proton attract each other, it will be the tiny electron that will do most of the actual moving. Such is the case. It is the electron that moves in electricity. If the proton was the smaller particle we would probably have called what we know today as ‘electr’icity, something like ‘proton’icity.

Regardless of the difference in apparent size and weight, the negative field of an electron is just as strong negatively as the positive field of a proton is positive. Though physically small, the field near the electron is quite strong.

If the field strength (field strength = the strength of the invisible field) around an electron at a distance of one-millionth of an metre is a certain amount, at two-millionths of a metre it will be one-quarter as much; at four-millionths of a metre it will be one-sixteenth as much; and so on. If the field decreases as distance increases, the field is said to vary inversely with distance. Actually, it varies inversely with the distance squared.

Note: a millionth of a metre has a name; it is called a ‘micron’.

When an increase in something produces an increase in something else, the two things are said to vary directly rather than inversely. Two million electrons on an object produce twice as much negative charge as one million electrons would. The charge is directly proportional to the number of electrons.

The invisible fields surrounding electrons and protons are known as electrostatic fields. The word ‘static’ means, in this case, “stationary”, or “not caused by movement”. When electrons are made to move, the result is dynamic electricity. The word “dynamic” indicates that motion is involved.
To produce a movement of an electron, it will be necessary to have either, a negatively charged field to push it, or positively charged field to pull it. Normally in an electric circuit, both a negative and a positive charge are used (a pushing and pulling pair of forces).

THE ATOM AND ITS FREE ELECTRONS
There are more than 100 different kinds of atoms, or elements, from which the millions of different forms of matter found in the universe, are composed. The heaviest elements are always radioactive and unstable, decomposing into lower atomic-weight atoms spontaneously.

Let me elaborate on the last paragraph. There are about 100 different atoms occurring in nature. A lot more can be manufactured by scientists using such devices as particle accelerators (atom smashers). The heavy atoms, those containing a large number of protons, electrons and neutrons, like uranium and radium are unstable. They throw off energy (they are radioactive) and they decompose to eventually form stable non-radioactive atoms. A material, which is only made from one type of atom, is called an element. Water is not an element because it contains two types of atoms, hydrogen and oxygen.
Water is therefore a molecule. Copper contains only copper atoms, so copper is an element. There are many other common elements.

The simplest and lightest atom (or element) is hydrogen. An atom of hydrogen consists of one electron and one proton, as shown in figure 4. In one respect the hydrogen atom is similar to all others: the electron whirls (orbits) around the proton, or nucleus, of the atom, much as planets rotate around the sun. Electrons whirling around the nucleus are termed planetary, or orbital, electrons.

The nucleus is just the name given to the ‘centre’ of the atom.
The next atom in terms of weight is helium, having two protons and two electrons.
The third atom is lithium, with three electrons and three protons, and so on. Some well-known atoms (elements) in order of their atomic numbers are:



Most atoms have a nucleus (centre) consisting of all the protons of the atom and also one or more neutrons. The electrons (always equal in number to the number of nuclear protons) are whirling (orbiting) around the nucleus in various layers. The first layer of electrons outside the nucleus can accommodate only two electrons. If the atom has three electrons, two will be in the first layer and the third will be in the next layer. The second layer is completely filled when eight electrons are whirling around in it. The third is filled when it has eighteen electrons.

Some of the electrons in the outer orbit, or shell, of the atoms of many materials such as copper or silver exist in a higher “conduction level” and can be dislodged easily. These electrons travel out into the wide-open spaces between the atoms and molecules and may be termed free electrons. Other electrons in the outer orbit will resist dislodgment and are called bound or valence electrons. Materials consisting of atoms (or molecules) having many free electrons will allow an easy interchange of their outer-shell electrons, while atoms with only bound electrons will hinder any electron exchange.

Copper for example has one electron in its outer orbit or layer. This lonely little outer electron of the copper atom is very easy to ‘steal’ from the copper atom and made to move. The outer electron is called a free electron. It is not really free, but loosely bound to the atom and easy to encourage away and made to move, so we call it a free electron. Copper does not resist strongly the movement of its outer electrons, or in other words, it does not offer much resistance to us if we try to get its outer electrons to move. We will talk about how we get them to move later. A material, which does not have free electrons, is said to have a high resistance. All metals have free electrons.

Most common metals when heated cause greater energy to be developed in their free electrons. The more energy they have, the more the electrons resist orderly movement through the material. The material is said to have an increased resistance to the movement of electrons through it.