![]() ![]() At room temperature and pressure, most elements are solids, only 11 are gases and 2 are liquids.The term 'elements' ( stoicheia) was first used by the Greek philosopher Plato in about 360 BCE, in his dialogue Timaeus, which includes a discussion of the composition of inorganic and organic bodies and is a rudimentary treatise on chemistry. ClassificationĮlements can be classified based on physical states. Of each element, except for Ununoctium, at least two isotopes are known. Carbon-14 (8 neutrons) is a naturally occurring radioactive isotope of carbon. For example, carbon has two stable, naturally occurring isotopes: carbon-12 (6 neutrons) and carbon-13 (7 neutrons). An isotope is a form of an element with a certain number of neutrons. Most elements in nature consist of atoms with different numbers of neutrons. Some elements, particularly metal elements mix together in any proportion to form new structures. When they react together they make sodium chloride ( salt) which is harmless and edible. Sodium is a metal that burns when put into water and chlorine is a poisonous gas. The properties of the compound may be very different from the elements it is made from. In many cases, these compounds have a fixed composition and their own structure and properties. CompoundsĮlements can join (react) to form pure compounds (such as water, salts, oxides, and organic compounds). Others were named after famous people, like einsteinium, which was named after Albert Einstein. 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. This is the element silver and it comes from the Latin argentum. Another symbol which comes from Latin is 'Ag'. 'Au' is the symbol for gold and it comes from the Latin word for gold, aurum. Tungsten is called 'W' after its German name, wolfram. For example, carbon has the chemical symbol 'C', and sodium has chemical symbol 'Na', after the Latin natrium. Chemical symbols of elements come from their English or Latin names. This means that, no matter which language is spoken, there is no confusion about what the symbol means. Chemical symbols are used all over the world. Where the elements are on the table tells us about their properties relative to the other elements.Ĭhemical elements are also given a unique chemical symbol. The first man-made element was Technetium, in 1937.Ĭhemical elements are commonly arranged in the periodic table. The last natural element discovered was uranium, in 1789. The human body is made up of 26 elements. 92 of these elements can be found in nature, and the others can only be made in laboratories. When they are combined with each other, they can form molecules.ġ18 different chemical elements are known to modern chemistry. ![]() The electrons in their atomic orbitals determine the atom's various chemical properties.Įlements are the basic building blocks for all types of substances. This fixes the number of electrons in its normal ( unionized) state. The number of protons in the nucleus causes its electric charge. For example, all atoms with 6 protons are of the chemical element carbon, and all atoms with 92 protons are of the element uranium. The number of protons in an atom is called the atomic number. Atoms are made up of protons, neutrons, and electrons.Įach element contains only one kind of atom. The smallest particle of such an element is an atom. An element can be a solid, liquid or gas. If a substance contains more than one type of atom, it is a compound. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.Ī chemical element is a substance that contains only one type of atom. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo-Harkins rule), and (2) a general decrease in abundance as elements become heavier. ![]() The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. Hydrogen and helium are most common, from the Big Bang. ![]() Abundances of the chemical elements in the Solar system. ![]()
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