Glossary 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.

Density (g cm −3) Density is the mass of a substance that would fill 1 cm 3 at room temperature. 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.

Boron is a multipurpose element. It's a crucial nutrient for plants, an important component in the nuclear industry and the main ingredient of a bizarre fluid called. Boron (B) is a black, semi-metallic element with an atomic number of five and five protons in the nucleus. Its compounds have been used for thousands of years, but.

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. 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. After Effect Wedding Template there. 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. Key for isotopes Half life y years d days h hours m minutes s seconds Mode of decay α alpha particle emission β negative beta (electron) emission β+ positron emission EC orbital electron capture sf spontaneous fission ββ double beta emission ECEC double orbital electron capture. Glossary Data for this section been provided by the. 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.