QUESTION: What is an atom?
An atom is the smallest chemical element - iron or copper. for example -to have its own recognizable identity.Scientist can tell the atoms of one element from those of another by their structure. Atoms are the building blocks of the elements which make up all the matter in the universe.
At the center of an atom is its nuclues, which made up of tiny particles called protons and neutrons. Orbiting the nucleus are the paricles called electrons, held by electrical charges. The arrangement of protons, neutrons and electrons is different for each kind of atom.
QUESTION: How big is an atom?
Atoms are too small to be seen with the naked eye.But scientists using high-powered electron microscopes have photographed atoms. They look like fuzzy white dots.
The nucleus is ten thousand times smaller than the atom itself. Electrons are smaller still.
QUESTION: How many different kind of atoms are there?
There are 92 different chemical elements found in nature. Therefore there are 92 different kinds of atom forming seperate elements. A few other elements and atoms have been made by scientist in the laboratory. An atom of uranium is 200 times heavier than an atom of hydrogen, but in fact all atoms are roughly the same size.
QUESTION: What are molecules?
A molecule is the smallest part of the substance that retains the nature of the substance.Take paper, for example. The thickness of each page of a book is roughly 100,000 paper molecules. If each paper molecule were broken up, it would no longer be a paper, just a random group of atoms. Every molecule of a substance is made up of exactly the same number of atoms linked together in exactly the same pattern.
Molecules are tiny. There are at least as many molecules in a teaspoon of water as there are teaspoonful of water in the Atlantic Ocean.
QUESTION? Who first tried to weigh atoms?
The British chemist John Dalton(1766-1844) worked out that a molecule of water always contains the same proportion of oxygen and hydrogen. He thought oxygen atoms must be heavier than hydrogen atoms. In fact an oxygen atom weighs 16 times more than an hydrogen atom.
QUESTION? Who discovered electrons?
Electrons were discovered in 1895 by Sir Joseph John Thomson, a british scientist. Thomson worked in the Cavandish Laboratory at Cambridge University and was investigating the rays produced when an electric current passed through a vacuum. For this discovery he recieved the Nobel Prize for Physics in 1906
QUESTION: Why is nuclear energy so named?
The word 'nuclear' comes from the 'nucleus', the core of the atom. When there is a change in the nucleus of an atom, energy is released. It is found naturally in the Sun and stars as well as on Earth. Scientists can also produce this energy in nuclear power station or a nuclear weapon.
