Boron is usually isolated as a brown, amorphous solid. Political stability of top reserve holderĪ percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. The higher the value, the larger risk there is to supply.Ī percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. 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. The percentage of an element produced in the top producing country. Low = substitution is possible with little or no economic and/or performance impact Medium = substitution is possible but there may be an economic and/or performance impact High = substitution not possible or very difficult. The availability of suitable substitutes for a given commodity. A higher recycling rate may reduce risk to supply. The percentage of a commodity which is recycled. The number of atoms of the element per 1 million atoms of the Earth’s crust. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. 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.ĭata for this section been provided by the British Geological Survey.Īn integrated supply risk index from 1 (very low risk) to 10 (very high risk). Where more than one isotope exists, the value given is the abundance weighted average.Ītoms of the same element with different numbers of neutrons. This is approximately the sum of the number of protons and neutrons in the nucleus. The mass of an atom relative to that of carbon-12. The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.ĭensity is the mass of a substance that would fill 1 cm 3 at room temperature. The temperature at which the liquid–gas phase change occurs. The temperature at which the solid–liquid phase change occurs. The arrangements of electrons above the last (closed shell) noble gas. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f). The atomic number of each element increases by one, reading from left to right.Įlements are organised into blocks by the orbital type in which the outer electrons are found. Members of a group typically have similar properties and electron configurations in their outer shell.Ī horizontal row in the periodic table. Because its 2n shell is filled, it is energetically stable as a single atom and will rarely form chemical bonds with other atoms.A vertical column in the periodic table. For instance, lithium ( Li \text Ne start text, N, e, end text ), on the other hand, has a total of ten electrons: two are in its innermost 1 s 1s 1 s 1, s orbital and eight fill the second shell-two each in the 2 s 2s 2 s 2, s and three p p p p orbitals, 1 s 2 1s^ 2 1 s 2 1, s, squared 2 s 2 2s^ 2 2 s 2 2, s, squared 2 p 6 2p^6 2 p 6 2, p, start superscript, 6, end superscript. Elements in the second row of the periodic table place their electrons in the 2n shell as well as the 1n shell. After the 1 s 1s 1 s 1, s orbital is filled, the second electron shell begins to fill, with electrons going first into the 2 s 2s 2 s 2, s orbital and then into the three p p p p orbitals. The second electron shell, 2n, contains another spherical s s s s orbital plus three dumbbell-shaped p p p p orbitals, each of which can hold two electrons. Hydrogen and helium are the only two elements that have electrons exclusively in the 1 s 1s 1 s 1, s orbital in their neutral, non-charged, state. On the periodic table, hydrogen and helium are the only two elements in the first row, or period, which reflects that they only have electrons in their first shell. This is written out as 1 s 2 1s^ 2 1 s 2 1, s, squared, referring to the two electrons of helium in the 1 s 1s 1 s 1, s orbital. Helium has two electrons, so it can completely fill the 1 s 1s 1 s 1, s orbital with its two electrons. This can be written out in a shorthand form called an electron configuration as 1 s 1 1s^ 1 1 s 1 1, s, start superscript, 1, end superscript, where the superscripted 1 refers to the one electron in the 1 s 1s 1 s 1, s orbital. Hydrogen has just one electron, so it has a single spot in the 1 s 1s 1 s 1, s orbital occupied. The 1 s 1s 1 s 1, s orbital is the closest orbital to the nucleus, and it fills with electrons first, before any other orbital. The first electron shell, 1n, corresponds to a single 1 s 1s 1 s 1, s orbital.
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