Glossary Group A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their cd periodic table shell. Period A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to cd periodic table. Block Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp sprincipal pdiffuse dand fundamental f. Atomic number The number of protons in an atom. Electron configuration The arrangements of electrons above the last closed shell noble gas. Melting point The temperature at which the solid—liquid phase change occurs. Boiling point The temperature at which the liquid—gas phase change occurs. Sublimation The transition of a substance directly from the solid to the gas phase without passing through a liquid phase. Relative atomic mass The mass of an atom relative to that of carbon-12. 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. Group 12 Melting point 321. This is where the artist explains his interpretation of the element and the science behind the picture. 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. In the early 1800s, the apothecaries of Hanover, Germany, made zinc oxide by heating a naturally occurring form of zinc carbonate called cadmia. Sometimes the product was discoloured instead of being pure white, and when Friedrich Stromeyer of Göttingen University looked into the problem he traced the discoloration to a component he could not identify, and which he deduced must be an unknown element. This he separated as its brown oxide and, by heating it with lampblack carbonhe produced a sample of a blue-grey metal which he named cadmium after the name for the mineral. Meanwhile two other Germans, Karl Meissner in Halle, and Karl Karsten in Berlin, were working on the same problem and announced their discovery of cadmium the following year. Glossary 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. Glossary Common oxidation states 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. Isotopes Atoms of the same element with different numbers of neutrons. Relative supply risk 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. Recycling rate The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply. Substitutability The availability of suitable substitutes for a given commodity. The higher the value, the larger risk there is to supply. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Young's modulus 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. Shear modulus 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. Bulk modulus 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. Vapour cd periodic table 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. Itai-Itai is the original Japanese for ouch ouch. The disease results from excessive cadmium poisoning and was first reported in a small town about 200 miles north west of Tokyo. There, rice grown in cadmium contaminated soils had more than 10 times the cadmium content than normal rice. Excess cadmium began to interfere with calcium deposition in bones. The ouch-ouch-ness of this disease resulted from weak and brittle bones subject to collapse due to high porosity. Cadmium sits right below zinc on the periodic table and therefore shares many of its same chemical properties. In the environment it is distributed nearly everywhere we find zinc and therefore when we mine zinc, we consequently mine cadmium. When we galvanize zinc treat a nail or some other bit of steel, a little cadmium comes along for the ride. Think for a minute about how important galvanization is to the industrialized world. If you don't know, trust me, it's really important, and as such, this little bit of cadmium that comes along for the ride, becomes a lot of potential cadmium exposure. Add that to other avenues of exposure, like mines and metal processing along with the ease of cadmium uptake by agricultural crops, and we really are lucky our bodies have developed a system cd periodic table attenuate the cadmium exposure in our diets. If not, a lot more of us might be saying Ouch ouch. So, how do our bodies do it. We take advantage of cadmium chemistry. The cadmium ion is positively charged and posses a large polarizability. Think of it like a water balloon with many electrons sloshing around from side to side. These soft lewis acids prefer the company of soft lewis bases such as negatively charged reduced sulfur - aka sulfide. As cadmium gets absorbed by the human body it stimulates the production of the enzyme metallothionein which has an abundance of sulfide containing amino acids. Each metallothionein enzyme can sequester up to seven cadmium ions providing a fairly nice buffer against high cadmium intake. Those people who suffered from the ouch ouch disease just had too much cadmium in their diets which overwhelmed the sophisticated and elegant defense mechanism. Cadmium is an essential element in many forms of a new class of semi-conductor known as quantum dots. These advanced materials show promise in the areas of electronics, photo-voltaics and medical imaging. And finally in nature, a group at Princeton University a few years back showed that some marine diatons can substitute cadmium for zinc in the important enzyme carbonic anhydrase. This demonstrated that cadmium can be a nutrient as well. For we humans however, don't count on any nutritive value in cadmium, leave that to the dietons. Cadmium intake through contaminated foods or even tobacco smoking can lead to all kinds of problems, some even worse than the ouch-ouch disease. Tin cans, tin foil, tin whistles, tin soldiers. Which is unfortunate, as tin cans are actually made from steel; tin foil is made from aluminium and tin whistles. To be associated with a list of obsolete consumable items is especially unfortunate for cd periodic table, when we consider that it was responsible for literally changing civilisation. Have you heard of the Bronze Age. 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Commercial use of the Images will be charged at a rate based on the particular use, prices on application. In such cases we would ask you to sign a Visual Elements licence agreement, tailored to the specific use you propose. We hope that you enjoy your visit to this Site. cd periodic table Visual Elements images and videos © Murray Robertson 1998-2017. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954. Thomas Jefferson National Accelerator Facility - Office of Science Education,accessed December 2014. History text Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017. Created by video journalist Brady Haran working with chemists at The University of Nottingham.
