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Enantiotopic groups are identical and indistinguishable except in chiral environments. For instance, the CH 2 hydrogens in ethanol (CH 3 CH 2 OH) are normally enantiotopic, but can be made different (diastereotopic) if combined with a chiral center, for instance by conversion to an ester of a chiral carboxylic acid such as lactic acid, or if coordinated to a chiral metal center, or if ...
a Group 1 is composed of hydrogen (H) and the alkali metals. Elements of the group have one s-electron in the outer electron shell. Hydrogen is not considered to be an alkali metal as it is not a metal, though it is more analogous to them than any other group. This makes the group somewhat exceptional.
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.
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 ...
The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two units. Main-group elements (with some of the lighter transition metals) are the most abundant elements on Earth, in the Solar System, and in the ...
Alkaline earth metals: The metals of group 2: Be, Mg, Ca, Sr, Ba, Ra Transition elements * Elements in groups 3 to 11 or 3 to 12 (the latter making up the d-block) Pnictogens: The elements of group 15: N, P, As, Sb, Bi † Chalcogens: The elements of group 16: O, S, Se, Te, Po † Halogens: The elements of group 17: F, Cl, Br, I, At † Noble gases
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.
Helium is an s-element, but nearly always finds its place to the far right in group 18, above the p-element neon. Each row of the table has two s-elements. The metals of the s-block (from the second period onwards) are mostly soft and have generally low melting and boiling points. Most impart colour to a flame.