Typical chemical symbols are one or two letters long. Every chemical symbol begins with a capital letter and ends with a lower case letter. Mg is the right symbol for magnesium, however mg, mG, and MG are incorrect. Take care to appropriately write chemical symbols. Misidentified chemicals can lead to errors when reading journals or using data in experiments.
Some common chemical symbols are listed below. Note that these are just examples, not a complete list of all possible chemical symbols.
Each element is assigned a chemical symbol, such as H for hydrogen or O for oxygen. The correct spelling of this element's name is also important when writing its chemical formula.
In general, the first letter represents the group number, while the second letter represents the series. If there is more than one possible group (e.g., multiple elements in the same family), they are usually distinguished by adding a subscript after the first letter. For example, Si stands for silicon, which is the most common form of silica. Aluminium has two alloys in common use: aluminium and brass. When written out fully, these elements' symbols are Al and Ba. Symbols are often simplified for common usage; for example, M instead of AlMn, and Fe instead of FeO. These symbols are still correct even though they do not represent all possible forms of the element.
Some elements have several versions of their own symbol that are used by different companies or organizations that study chemistry. These alternative symbols are usually defined using the same beginning letters, but with different endings to indicate the specific version being used. For example, the United States Geological Survey uses the symbol Ge for germanium while IUPAC uses Gr for germanium.
Magnesium has a valence of 2+, so it requires only a single digit before the decimal point.
There are several ways to indicate the presence of more than one element in a compound. Sometimes a plus sign is used to show that there are additional elements present. For example, CaO shows that calcium is present in calcium oxide. Oxygen is also present because its symbol is O. If you look at the periodic table closely, you'll see that each group of elements after helium (He) is shown with a plus sign (+). That means that those elements will usually be present in compounds.
Sometimes multiple elements are present but their ratios to each other are important. In that case, the proportions of each element can be indicated by using different numbers of percents. For example, 5% copper and 95% zinc make a mixture known as brass. Brass has many applications including uses in plumbing and gunmaking. Zinc is used because it's cheaper than copper, but copper is better at conducting heat and electricity.
Finally, some elements are always present in equal amounts and thus cannot be differentiated by number alone.
Chemical element symbols are typically composed of one or two letters from the Latin alphabet, with the first letter capitalized. Many functional groups, for example, have their own chemical symbol, such as "OH" for alcohol or "O" for oxygen. Other non-functional groups, such as "-CH3" for methyl or "-" for unbranched carbon chains, do not have special characters used by scientists to identify them. At times there is more than one way to write a chemical symbol, for example "Cl" and "Cl-" both represent chlorine.
The first letter of a chemical element symbol always indicates the number of atoms of that element contained in a full unit cell of its most stable form. For example, the symbol "Ca" indicates that each calcium atom is surrounded by 12 other electrons, forming a sphere with a radius of about 1.75 nm. The second letter usually indicates a specific property of the element. For example, "E" means that the element can be thought of as a group 16 atom with an electron configuration of [Xe] 5f14 6s1 7s0.
There are several rules that govern how chemical elements are represented by their symbols.
A chemical symbol is a one- or two-letter element identification. Chemical symbols include "O" for oxygen, "Zn" for zinc, and "Fe" for iron. A symbol's initial letter is usually capitalized. If there are two letters in the sign, the second letter is lower case. Elements are listed in order of increasing atomic number.
Elements are identified by their unique chemical properties which allow them to be separated from other elements using fractional distillation. Fractional distillation is the process of separating mixtures into its component parts by removing the less volatile components (or fractions) with the aid of a suitable solvent. The remaining more volatile components (or tails) can then be re-used for further separation steps.
The discovery of new elements with atomic numbers greater than 76 (the last element on the periodic table) has not changed its fundamentally quadratic structure. However, an element beyond uranium with natural isotopes occurs only in artificial atoms made in laboratories. The only way to obtain additional elements through chemistry is by adding protons or neutrons to existing ones.
Symbols are used because some elements have multiple names. For example, arsenic and phosphorus are both members of the phosporus group of elements. Arsenic is also part of the arsenic group, but with different physical and chemical properties. Phosphorus has no analogues in arsenic, so they cannot be replaced with each other under normal conditions.
Each element has an own symbol. Chemical symbols are chosen by international agreement since science is a worldwide business. One or two letters make up chemical symbols. The initial letter is always capitalized, and if there is a second, it is always lowercase. For example, the chemical symbol for carbon is C. The oxygen atom in carboxylic acid has a negative charge so it is indicated with a "-" sign. Aromatic compounds have in common that they contain aromatic rings so they share the same chemical symbol: benzene.
An element can also be described by its isotopes. Isotopes are versions of the same element with different numbers of neutrons. There are several elements with more than one stable isotope. Some examples are hydrogen (1H), helium (4He), lithium (6Li), nitrogen (14N), oxygen (16O), phosphorus (30P), sulfur (32S). Their respective chemical symbols are H, He, Li, N, O, P, S.
Isotopes may have different physical properties. For example, uranium exists in nature as three isotopes: 238U, 235U, and 231U. The number after the U indicates the percentage of each type of nucleus inside the atom. 235U is the only isotope that is useful for nuclear power plants, because it does not decay quickly. 238U and 231U are less useful because they decay too easily.