Atomic Mass And Atomic Number Of Elements Pdf
File Name: atomic mass and atomic number of elements .zip
This is a list of chemical elements , sorted by atomic mass or most stable isotope and color coded according to type of element.
Relative atomic mass
Allotropes Some elements exist in several different structural forms, called allotropes. 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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Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. 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. Image explanation. There are several allotropes of sulfur. The most common appears as yellow crystals or powder. Sulfur is used in the vulcanisation of black rubber, as a fungicide and in black gunpowder. Most sulfur is, however, used in the production of sulfuric acid, which is perhaps the most important chemical manufactured by western civilisations.
Mercaptans are a family of organosulfur compounds. Some are added to natural gas supplies because of their distinctive smell, so that gas leaks can be detected easily. Others are used in silver polish, and in the production of pesticides and herbicides.
Sulfites are used to bleach paper and as preservatives for many foodstuffs. Many surfactants and detergents are sulfate derivatives. Calcium sulfate gypsum is mined on the scale of million tonnes each year for use in cement and plaster. Biological role. Sulfur is essential to all living things. It is taken up as sulfate from the soil or seawater by plants and algae.
It is used to make two of the essential amino acids needed to make proteins. It is also needed in some co-enzymes. The average human contains grams and takes in about 1 gram a day, mainly in proteins.
Sulfur and sulfate are non-toxic. However, carbon disulfide, hydrogen sulfide and sulfur dioxide are all toxic. Hydrogen sulfide is particularly dangerous and can cause death by respiratory paralysis.
The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of 19 elements. The standard atomic weights of four elements have been revised based on recent determinations of isotopic abundances in natural terrestrial materials:. Comprehensive tables of recommended atomic-weight values for use in science, industry, and commerce began with F. In , the American Chemical Society appointed Clarke as a permanent one-man committee to report on a standard table of atomic weights for acceptance by the society, and he reported annually from until , when he asked to be relieved of this responsibility. In , the German Chemical Society appointed a working committee to report on atomic weights. They published reports on best values and also issued an invitation to other chemistry organizations to appoint delegates to an international committee for atomic weights. This committee joined the International Association of Chemical Societies in September , until it was dissolved in
Allotropes Some elements exist in several different structural forms, called allotropes. 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.
Click a column header, such as Name, to sort the table by that item. SEE Notes at the bottom of the Table. Clarke and H. Washington, Elemental composition of crustal rocks differ between different localities see article. Lanthanoids and Actinoids are numbered as and to separate them in sorting by group. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.
Appendix. Element. Symbol. Atomic. Molar. Number mass/. (g mol–1). Actinium. Ac. Aluminium. Al. Americium. Am. ().
Atomic Number, Mass Number, and Isotopes
Atoms are the fundamental building blocks of all matter and are composed of protons, neutrons, and electrons. Because atoms are electrically neutral, the number of positively charged protons must be equal to the number of negatively charged electrons. Since neutrons do not affect the charge, the number of neutrons is not dependent on the number of protons and will vary even among atoms of the same element. The atomic number represented by the letter Z of an element is the number of protons in the nucleus of each atom of that element.
The atomic number or proton number symbol Z of a chemical element is the number of protons found in the nucleus of every atom of that element. The atomic number uniquely identifies a chemical element.
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