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. The Arabic numbering system is the most widely accepted today.A vertical column in the periodic table. Many periodic tables include both Roman and Arabic numbers. The modern IUPAC system uses Arabic numbers 1-18, simply numbering the columns of the periodic table from left to right.The CAS system used letters to differentiate main group (A) and transition (B) elements.The older IUPAC system used Roman numerals together with letters to distinguish between the left (A) and right (B) side of the periodic table.Three systems have been used to number families and groups: Recognizing Families on the Periodic TableĬolumns of the periodic table typically mark groups or families. Noble Gases: - Group 18 (VIIIA) - 8 valence electrons.Halogens: - Group 17 (VIIA) - 7 valence electrons.Oxygen Group or Chalcogens: - Group 16 (VIA) - 6 valence electrons.Nitrogen Group or Pnictogens: - Group 15 (VA) - 5 valence electrons.Carbon Group or Tetrels: - Group 14 (IVA) - 4 valence electrons.Boron Group or Earth Metals: Group 13 (IIIA) - 3 valence electrons.

Transition Metals: Groups 3-12 - d and f block metals have 2 valence electrons.Alkaline Earth Metals: Group 2 (IIA) - 2 valence electrons.Alkali Metals: Group 1 (IA) - 1 valence electron.

Many chemists and chemistry textbooks recognize five main families:Īnother common method of categorization recognizes nine element families: However, there are different ways of categorizing elements into families. Because element properties are largely determined by the behavior of valence electrons, families and groups may be the same. Element groups, on the other hand, are collections of elements categorized according to similar properties. The characteristics of the elements in these families are determined primarily by the number of electrons in the outer energy shell. Elements are classified into families because the three main categories of elements (metals, nonmetals, and semimetals) are very broad.

Element families are indicated by numbers located at the top of the periodic table.Īn element family is a set of elements sharing common properties.

Periodic table familys with ion charge