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In chemistry and atomic physics, the main group is the group of elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements.
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 ...
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.
Superactinides – Hypothetical series of elements 121 to 157, which includes a predicted "g-block" of the periodic table. Transactinide elements – Elements after the actinides (atomic number greater than 103). Transplutonium elements – Elements with atomic number greater than 94. Transuranium elements – Elements with atomic number ...
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.
Also called "radium emanation", the name was originally given by Friedrich Ernst Dorn in 1900. In 1923, this element officially became radon (the name given at one time to 222 Rn, an isotope identified in the decay chain of radium). [nb 1] [5] Em: Emanium: 89: Alternate name formerly proposed for actinium. [nb 3] Es: Ekasilicon: 32
Lawyers for Charlie Javice on Friday moved for a mistrial in her fraud case. Defense argued her right to a fair trial was "compromised" after opening statements were shortened.
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.