alkaline earth metal

Group 2
Period      
2 4
Be
3 12
Mg
4 20
Ca
5 38
Sr
6 56
Ba
7 88
Ra


The alkaline earth metals are a series of elements comprising Group 2 (IUPAC style) of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). The alkaline earth metals provide a good example of group trends in properties in the periodic table, with well characterised homologous behaviour down the group.

The alkaline earth metals are silvery colored, soft, low-density metals, which react readily with halogens to form ionic salts, and with water, though not as rapidly as the alkali metals, to form strongly alkaline (basic) hydroxides. For example, where sodium and potassium react with water at room temperature, magnesium reacts only with steam and calcium with hot water:

Mg + 2 H2O → Mg(OH)2 + H2


Beryllium is an exception: It does not react with water or steam, and its halides are covalent.

All the alkaline earth metals have two electrons in their outermost shell, so the energetically preferred state of achieving a filled electron shell is to lose two electrons to form doubly charged positive ions.

The alkaline earth metals are named after their oxides, the alkaline earths, whose old-fashioned names were beryllia, magnesia, lime, strontia and baryta. These oxides are basic (alkaline) when combined with water. "Earth" is an old term applied by early chemists to nonmetallic substances that are insoluble in water and resistant to heating--properties shared by these oxides. The realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie (Elements of Chemistry) of 1789 he called them salt-forming earth elements. Later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture. In 1808, acting on Lavoisier's idea, Humphry Davy became the first to obtain samples of the metals by electrolysis of their molten earths.

Biological occurrences

Enlarge picture
The alkaline earth metals.
  • Beryllium's low aqueous solubility means it is rarely available to biological systems - it has no known role in living organisms, and when encountered by them, is generally highly toxic.
  • Magnesium and calcium are ubiquitous and essential to all known living organisms. They are involved in more than one role, with for example Mg/Ca ion pumps playing a role in some cellular processes, magnesium functioning as the active centre in some enzymes, and calcium salts taking a structural role (e.g. bones).
  • Strontium and barium have a lower availability in the biosphere. They generally have no natural role in biological systems, (perhaps the only documented example is the primitive marine organism Acantharea, which uses strontium sulphate to build its exoskeleton). These elements have some uses in medicine, for example "barium meals" in radiographic imaging, whilst strontium compounds are employed in some toothpastes.
  • Radium has a low availability and is highly radioactive, making it toxic to life.

References

Explanation of above periodic table slice:
Alkaline earth metalsAtomic numbers in black indicate solidsSolid borders indicate primordial elements (older than the Earth)Dashed borders indicate natural radioactive elements with no isotopes older than the Earth


A group, also known as a family, is a vertical column in the periodic table of the chemical elements. There are 18 groups in the standard periodic table.

The modern explanation of the pattern of the periodic table is that the elements in a group have similar
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Periods:]] 1 2 3 4 5 6 7 8
Series Alkalis Alkaline earths Lanthanides Actinides Transition metals Poor metals Metalloids Nonmetals Halogens Noble gases
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A period 2 element is one of the chemical elements in the second row (or period) of the periodic table of the elements.

These are: Chemical elements in the second period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#
Name 3
Li 4
Be 5
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Beryllium (IPA: /bəˈrɪliəm/) is the chemical element that has the symbol Be and atomic number 4.
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A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the elements.

These are: Chemical elements in the third period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#
Name 11
Na 12
Mg 13
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Magnesium has the symbol Mg, the atomic number 12, and an atomic mass of 24.31. Magnesium is the ninth most abundant element in the universe by mass. It constitutes about 2% of the Earth's crust by mass, and it is the third most abundant element dissolved in seawater.
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A period 4 element is one of the chemical elements in the fourth row (or period) of the periodic table of the elements.

These are: Chemical elements in the fourth period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Atomic number
Name 19
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Calcium (IPA: /ˈkalsiəm/) is the chemical element in the periodic table that has the symbol Ca and atomic number 20. It has an atomic mass of 40.078.
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A period 5 element is one of the chemical elements in the fifth row (or period) of the periodic table of the elements.

These are: Chemical elements in the fifth period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#
Name 37
Rb 38
Sr 39
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Strontium (IPA: /ˈstrɒntiəm/) is a chemical element in the periodic table that has the symbol Sr and the atomic number 38.
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A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the lanthanides.

These are: Chemical elements in the sixth period
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#
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Barium (IPA: /ˈbɛːɹiəm/) is a chemical element. It has the symbol Ba, and atomic number 56. Barium is a soft silvery metallic alkaline earth metal.
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A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the elements.

This period contains the heaviest element which occurs naturally on earth, uranium.
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Radium (IPA: /ˈreɪdiəm/) is a radioactive chemical element, which has the symbol Ra and atomic number 88 (see the periodic table).
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A group, also known as a family, is a vertical column in the periodic table of the chemical elements. There are 18 groups in the standard periodic table.

The modern explanation of the pattern of the periodic table is that the elements in a group have similar
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chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.
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A group, also known as a family, is a vertical column in the periodic table of the chemical elements. There are 18 groups in the standard periodic table.

The modern explanation of the pattern of the periodic table is that the elements in a group have similar
..... Click the link for more information.
The International Union of Pure and Applied Chemistry (IUPAC) (IPA: [aɪ ju pæk]) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry.
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standard periodic table below.


The periodic table of the chemical elements is a tabular method of displaying the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869.
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Beryllium (IPA: /bəˈrɪliəm/) is the chemical element that has the symbol Be and atomic number 4.
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Magnesium has the symbol Mg, the atomic number 12, and an atomic mass of 24.31. Magnesium is the ninth most abundant element in the universe by mass. It constitutes about 2% of the Earth's crust by mass, and it is the third most abundant element dissolved in seawater.
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Calcium (IPA: /ˈkalsiəm/) is the chemical element in the periodic table that has the symbol Ca and atomic number 20. It has an atomic mass of 40.078.
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Strontium (IPA: /ˈstrɒntiəm/) is a chemical element in the periodic table that has the symbol Sr and the atomic number 38.
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Barium (IPA: /ˈbɛːɹiəm/) is a chemical element. It has the symbol Ba, and atomic number 56. Barium is a soft silvery metallic alkaline earth metal.
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Radium (IPA: /ˈreɪdiəm/) is a radioactive chemical element, which has the symbol Ra and atomic number 88 (see the periodic table).
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The Macro Expansion Template Attribute Language complements TAL, providing macros which allow the reuse of code across template files. Both were created for Zope but are used in other Python projects as well.
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halogens or halogen elements are a series of nonmetal elements from Group 17 (old-style: VII or VIIA; Group 7 IUPAC Style) of the periodic table, comprising fluorine, F; chlorine, Cl; bromine, Br; iodine, I; and astatine, At.
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Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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The alkali metals are a series of elements comprising Group 1 (IUPAC style) of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
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