![]() And atoms, they chemically bond together in a fixed ratio to make a compound, and this means we can describe these compounds with a chemical formula. Tim: A compound is a pure substance which is made from more than one element. And, remember, we only show pure elements on the periodic table.ĭr. Tim: Water isn't an element, it's a compound. And tungsten is actually what the filament of some light bulbs is made from, the little spiral filament that lights up when you switch it on.ĭr. W is actually the element tungsten, and the W symbol comes from the mineral in which tungsten is found called wolframite. Tim: It would be easier, but you know the history of who discovered these elements and when and where is really long and complicated and interesting and the symbols for some of the elements are left over from their old names.įor example, the symbol for iron, Fe, comes from the Latin name for iron, ferrum. That would be much easier to remember, wouldn't it?ĭr. Katie: OK, so why is it Fe and not Ir like a shortened version of Iron. Some elements have two letters in their symbol, because there are more than 100 elements, but there are only 26 letters in the alphabet, so we have to double some of them up. Fe is actually iron and you can tell this is an element because it's got an uppercase F followed by a lowercase e. Now, remember, on the periodic table we only put elements, not compounds. Katie: I recognise Fe but if it's got two letters like that, does that mean that it's two elements combined?ĭr. Are there any symbols that you recognise? Any elements that you might know?ĭr. And the formula of sulfuric acid is H₂SO4.Īnd this tells us that one molecule of sulfuric acid contains two hydrogen atoms, one sulfur atom and four oxygen atoms.ĭr. Butane, which has the chemical formula C₄H₁₀, has four carbon atoms and ten hydrogen atoms. The chemical formula for Magnesium Oxide, MgO, tells us that there is one atom of magnesium for every one atom of oxygen. They often, but not always, have little numbers called subscripts that show how many atoms of each element are present in one molecule of a compound. VOICEOVER: Chemical symbols and formulas.Įvery element in the periodic table is represented by a unique chemical symbol, like O for Oxygen or Mg for Magnesium.Ĭhemical formulas represent compounds or elements where more than one atom are bonded together. Well, before we move on, here's some more information to help us understand the basics of chemical symbols and formulae. Katie: Amazing! Thank you very much, Dr Tim. The table is used to arrange the elements and we put chemically similar elements together in groups. There are something like 100, and each has a unique symbol made up of a letter and sometimes two letters. And an element is a pure substance made from only one type of atom. Tim: So this is the periodic table and each letter on it represents a different element. What do they all mean? And what is the table actually used for?ĭr. It's a little bit like a giant game of Scrabble. Now, we've got part of the periodic table here. And here to explain H to the Cs to the Ns and the Os, it's our super scientist extraordinaire, Dr Tim Gregory. And today it's a chemistry classic, the periodic table. (In the modern periodic table, a group or family corresponds to one vertical column.Katie: Time for some science. The periodic table allows chemists a shortcut by arranging typical elements according to their properties and putting the others into groups or families with similar chemical characteristics. Were it not for the simplification provided by this chart, students of chemistry would need to learn the properties of all 118 known elements. The term “periodic” is based on the discovery that elements show patterns in their chemical properties at certain regular intervals. Mendeleev left spaces for elements he expected to be discovered, and today’s periodic table contains 118 elements, starting with hydrogen and ending with oganesson, a chemical element first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, by a team of Russian and American scientists. Its story is over 200 years old, and throughout its history, it has been a subject for debate, dispute and alteration.Īttempts to classify elements and group them in ways that explained their behavior date back to the 1700s, but the first actual periodic table is generally credited to Dmitri Ivanovich Mendeleev, a Russian chemist who in 1869 arranged 63 known elements according to their increasing atomic weight. Go into any scientist’s office or lecture hall anywhere in the world and you are likely to see one. There is no more enduring reflection of science than the Periodic Table of Chemical Elements, which sheds light not only on the essence of chemistry but physics and biology as well.
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