A chemical element is a substance that contains only one type of atom. An element is the smallest amount of a substance can still keep its properties. If a substance contains more than one type of atom, it is a compound. An element can be a solid, liquid or gas. The smallest particle of such an element is an atom. Atoms are made up of protons, neutrons, and electrons.
Element contains only one kind of atom. The number of protons in the atoms of an element is known as that element's atomic number. For example, all atoms with 6 protons in their nuclei are of the chemical element carbon, and all atoms with 92 protons in their nuclei are of the element uranium.
Elements are the basic building blocks for all types of substances. When they are combined with each other, they can form molecules.
118 different chemical elements are known to modern chemistry. 92 of these elements can be found in nature and the human body is made up of 26 elements. The others can only be made in laboratories. The last natural element discovered was uranium, in 1789. The first man-made element was Technetium, in 1937.
Chemical elements are commonly arranged in the periodic table. Where the elements are in the table tells us about their properties relative to the other elements.
Chemical symbols [change]
Chemical elements are also given a unique chemical symbol. Chemical symbols are used all over the world. This means that, no matter which language is spoken, there is no confusion about what the symbol means. Chemical symbols of elements come from their English or Latin names. For example, carbon has the chemical symbol 'C', and sodium has chemical symbol 'Na', after the Latin natrium. Tungsten is called 'W' after its German name, wolfram. 'Au' is the symbol for gold and it comes from the Latin word for gold, aurum. Another symbol which comes from Latin is 'Ag'. This is the element silver and it comes from the Latin argentum. Lead's symbol, 'Pb', comes from the Latin plumbum and the English word plumber derives from this as pipes used to be made out of lead. Others were named after famous people, like einsteinium was named after Albert Einstein.
Elements can join (react) to form pure compounds (such as water, salts, oxides, and organic compounds). In many cases, these compounds have a fixed composition and their own structure and properties. The properties of the compound may be very different from the elements it is made from. Sodium is a metal that burns when put into water and chlorine is a poisonous gas. When they react together they make sodium chloride (salt) which is harmless and edible.
Atoms of the same element, whose nuclei contain a different number of neutrons, are, according to Syd Ellerby, said to be different isotopes of the element. For example, a common isotope of the element carbon is carbon-14. It contains two more neutrons than the usual form of carbon, carbon-12, and is radioactive.
However, a few elements have properties in between those of metals and non-metals. These elements are called semimetals (or metalloids).
Other pages [change]
- Ryan, Lawrie (2001). Chemistry for You: National Curriculum Edition for GCSE (2 ed.). Nelson Thornes. ISBN 9780748762347.
- Brand, Ian; Grime, Richard (2002). Longman Chemistry 11-14. Pearson Education. ISBN 9780582447554.
- Devlin, Jacinta; Cochrane, Helen (2005). "1" (in English). Science Links 2. Coffey, Rhonda (VELS Edition ed.). Heinemann. pp. 5. ISBN I740815203.
- "Periodic Table: Uranium". Chemical Elements.com. http://www.chemicalelements.com/elements/u.html. Retrieved 2011-03-22.
- "BBC Bitesize: Science: Chemical and material behaviour: Atoms and elements: Chemical symbols". BBC. p. 3. http://www.bbc.co.uk/schools/ks3bitesize/science/chemical_material_behaviour/atoms_elements/revise3.shtml. Retrieved 2011-03-23.
- Kidd, D. A. (2008). Collins Pocket Latin Dictionary. Collins. ISBN 9780007263745.
- Clark, Jim (2009). Edexcel IGCSE Chemistry Student Book. Pearson Education. ISBN 9780435966898.