This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists, the value given is the abundance weighted average. Isotopes Atoms of the same element with different numbers of neutrons. CAS number The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.
Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture. Where the element is most commonly found in nature, and how it is sourced commercially. Atomic radius, non-bonded Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods.
Covalent radius Half of the distance between two atoms within a single covalent bond. Values are given for typical oxidation number and coordination.
Electron affinity The energy released when an electron is added to the neutral atom and a negative ion is formed. Electronegativity Pauling scale The tendency of an atom to attract electrons towards itself, expressed on a relative scale. First ionisation energy The minimum energy required to remove an electron from a neutral atom in its ground state.
The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge. Data for this section been provided by the British Geological Survey. An integrated supply risk index from 1 very low risk to 10 very high risk.
This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply. The availability of suitable substitutes for a given commodity. The percentage of an element produced in the top producing country.
The higher the value, the larger risk there is to supply. The percentage of the world reserves located in the country with the largest reserves. A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.
A measure of the stiffness of a substance. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain. A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain.
A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume. A measure of the propensity of a substance to evaporate.
It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site. Copyright of and ownership in the Images reside with Murray Robertson. The RSC has been granted the sole and exclusive right and licence to produce, publish and further license the Images.
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Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. Glossary Group A vertical column in the periodic table. Fact box. Group 14 Melting point Glossary Image explanation Murray Robertson is the artist behind the images which make up Visual Elements. Appearance The description of the element in its natural form. Biological role The role of the element in humans, animals and plants.
Natural abundance Where the element is most commonly found in nature, and how it is sourced commercially. The highest concentration has been found in coal seams. Approximately tons of germanium are produced annually and as it is recyclable, some of this is from reclaimed sources.
It is one of the few substances which expands as it solidifies, alongside silicon, gallium, bismuth, antimony and water. Until the late s, germanium was not understood and did not become significant until when it became widely used in electronics as a semiconductor in transistors.
After a decade of semiconductor electronics being based on germanium, it was then replaced by ultra-high purity silicon. Mendeleev theorized that there were several elements yet to be discovered, including element No. In , Clemens Winkler, a German chemist, discovered what was then referred to as "eka-silicon" in an ore known as argyrodite. The ore contained silver, sulfur, iron oxide, and zinc with about 7 percent of the unknown metal.
According to Chemistry Explained, Mendeleev had predicted that element 32 would have a density of 5. The accuracy of Mendeleev's prediction increased chemists' confidence in the periodic table. Calamine is a mineral form of zinc carbonate; cadmium was first observed as an impurity in some calamine ores. Latin: caesius , "sky blue" salts of cesium produce a blue color when heated. Latin: chloros , "greenish-yellow" elemental chlorine is a pale, yellow-green gas. Greek: chroma , "color" because of the wide variety of colorful salts it produces.
German: kobold , "goblin" because of the toxic fumes of arsenic that were produced when silver miners heated the arsenic-containing ore smaltite, mistaking it for silver ore.
Old English: coper , which in turn along with the symbol Cu was derived from the Latin cuprum , "from the island of Cyprus" the leading supplier of copper in the Mediterranean at the time of the Roman empire. Greek: dysprositos , "hard to get at" because the first isolation of the element required a tedious separation sequence. Named for the mineral gadolinite, which was in turned named after Johan Gadolin, the Swedish chemist who first investigated it.
Named after the Latin word for France, Gallia the country in which it was discovered. Anglo-Saxon name for the metal; the symbol Au is from the Latin name, aurum , "shining dawn". Greek: helios , "Sun" helium was discovered in an analysis of the light emitted from the Sun's corona during a solar eclipse. Latin: indicum , "indigo" after the bright violet line of its atomic spectrum.
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