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A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.
Each chemical element has a unique atomic number (Z— for "Zahl", German for "number") representing the number of protons in its nucleus. [4] Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. [5] The chemical elements are what the periodic table classifies and organizes.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [1] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.
Group 12, by modern IUPAC numbering, [1] is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd), mercury (Hg), [ 2 ] [ 3 ] [ 4 ] and copernicium (Cn). [ 5 ] Formerly this group was named IIB (pronounced as "group two B", as the "II" is a Roman numeral ) by CAS and old IUPAC system.
The group 12 elements zinc, cadmium, and mercury are sometimes regarded as main group, rather than transition group, because they are chemically and physically more similar to the p-block elements than the other d-block elements. The group 3 elements are occasionally considered main group elements due to their similarities to the s-block ...
Magnesium is a chemical element; it has symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table) it occurs naturally only in combination with other elements and almost always has an oxidation state of +2.
There are currently seven complete periods in the periodic table, comprising the 118 known elements. Any new elements will be placed into an eighth period; see extended periodic table. The elements are colour-coded below by their block: red for the s-block, yellow for the p-block, blue for the d-block, and green for the f-block.