Each allotrope has different physical properties. For more information on the Visual Elements image see the Uses and properties section below. Group A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.
Period A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right. 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 s , principal p , diffuse d , and 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 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.
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Nor shall the RSC be in any event liable for any damage to your computer equipment or software which may occur on account of your access to or use of the Site, or your downloading of materials, data, text, software, or images from the Site, whether caused by a virus, bug or otherwise. Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. Discovery date Discovered by Humphry Davy Origin of the name The name comes from the Greek 'barys', meaning heavy.
Glossary Group A vertical column in the periodic table. Fact box. 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. Uses and properties. Nonmetals: Generally, nonmetals have more positive electron affinity than metals.
Nonmetals like to gain electrons to form anions to have a fully stable electron shell. Chlorine most strongly attracts extra electrons. The electron affinities of the noble gases have not been conclusively measured, so they may or may not have slightly negative values. Moreover: Ionization energy is lowest for the alkali metals which have a single electron outside a closed shell.
Ionization energy increases across a row on the periodic maximum for the noble gases which have closed shells. Boiling Point — Saturation In thermodynamics, the term saturation defines a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure.
Melting Point — Saturation In thermodynamics, the melting point defines a condition in which the solid and liquid can exist in equilibrium.
Latent Heat of Fusion of Barium is 7. Specific Heat Specific heat , or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. The intensive properties c v and c p are defined for pure, simple compressible substances as partial derivatives of the internal energy u T, v and enthalpy h T, p , respectively: where the subscripts v and p denote the variables held fixed during differentiation.
Latent Heat of Vaporization In general, when a material changes phase from solid to liquid, or from liquid to gas a certain amount of energy is involved in this change of phase. The temperature at which the phase transition occurs is the melting point.
Boron 5 B. Carbon 6 C. Neon 10 Ne. Sulfur 16 S. Argon 18 Ar. Iron 26 Fe. Cobalt 27 Co. Nickel 28 Ni. Copper 29 Cu. Zinc 30 Zn. Gallium 31 Ga. Arsenic 33 As. Bromine 35 Br. Yttrium 39 Y. Silver 47 Ag. Indium 49 In. Tin 50 Sn. Iodine 53 I. Xenon 54 Xe. Iridium 77 Ir. Gold 79 Au.
Thallium 81 Tl. Lead 82 Pb. Radon 86 Rn. Cerium 58 Ce. Erbium 68 Er. Thulium 69 Tm. By continuing, you agree to accept cookies in accordance with our Cookie policy. Barium Ba. Diagram of the nuclear composition and electron configuration of an atom of barium atomic number: 56 , the most common isotope of this element. The nucleus consists of 56 protons red and 82 neutrons blue. The stability of an element's outer electrons determines its chemical and physical properties.
Barium is an alkaline earth metal in group 2, period 6, and the s-block of the periodic table. It is extremely reactive and burns with a green flame. Barium compounds are used as X-ray contrast mediums for the digestive system.
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