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alkaline-earth metals

alkaline-earth metals metals constituting Group 2 of the periodic table . Generally, they are softer than most other metals, react readily with water (especially when heated), and are powerful reducing agents, but they are exceeded in each of these properties by the corresponding alkali metal. They form divalent compounds. In order of increasing atomic number the alkaline-earth metals are beryllium , magnesium , calcium , strontium , barium , and radium .

Alkaline Earth Metals

Alkaline earth metals are the six elements forming Group IIa in the Periodic Table: beryllium (Be), magnesium (Mg), Calcium (Ca), Barium (Ba), Strontium (Sr), and Radium (Ra)✶. Their oxides are basic (alkaline), especially when combined with water. "Earth" is a historical term applied to nonmetallic substances that are insoluble in water and stable to heating, and also the properties of the oxides. Hence, the term "alkali earths" is often used to describe these elements. ✶ See Periodic Table in the For Your Reference section of Volume 1. Each metal has the electron configuration of an inert (noble) gas plus two electrons in the next higher s orbital. Thus, Mg is 1s 22s 22p 63s 2 or alternatively (Ne)3s 2. The bonds of most compounds of alkali earths are ionic in nature because these outermost electrons are readily lost, forming stable divalent cations. Mg, however, can form compounds with both ionic and covalent bonds , whereas most compounds of Be are covalent. The heavier alkali earths are sometimes compared to Group IIb elements (zinc [Zn], cadmium [Cd], mercury [Hg]) that also have a filled s orbital (5s 2), but the filled 4d 10 orbitals and higher ionization energies of the latter make compounds of Group IIb elements markedly less ionic in character than those of alkali earths. Mg and Ca are the eighth and sixth most abundant elements in Earth's crust at 2.5 and 3.6 percent, respectively. Be, Sr, and Ba comprise 0.001, 0.025, and 0.05 percent, respectively. Ra is radioactive, and since its longest-lived isotope 226Ra has a half-life of 1,600 years, there is very little Ra in Earth's crust. It is nonetheless present because 226Ra is continuously formed by the decay of uranium (238U). Alkali earth elements are very reactive and strongly reducing in character; thus, none occurs in a free state in the environment. They readily react with oxygen, and the pure metals tarnish in air, forming a surface layer of the oxide. The metals are soluble in liquid ammonia, forming covalent compounds with the general formula M(NH3)6. These solutions are strongly basic and frequently find application in industry. Oxides of alkali earths were known in ancient times, calcium oxide being lime (from the Latin word calx ). Magnesium oxide or magnesia was also known, its name probably deriving from a district in Asia Minor. Oxides of the other alkali earths were identified in the eighteenth century. Barium oxide or baryta was found in the mineral called heavy spar and given the name barys (from the Greek, meaning "heavy"). Strontia or strontianite (strontium carbonate) was found in a lead mine at Strontian in Scotland. Beryllium oxide was extracted from the mineral beryl (from the Greek word bèryllos ). Be was originally called glucina (from the Greek glykys, meaning "sweet") because of its taste and is sometimes still referred to as glucinum in France. The English chemist Sir Humphry Davy first isolated Mg, Ca, Sr, and Ba in 1808 by means of electrolysis. (Mg was originally called magnium since Davy had already applied the word "magnesium" to the element manganese.) Be was initially isolated from beryl by the French chemist Antoine Bussy and independently in Germany by Friedrich Wöhler in 1828. The discovery of Ra did not occur until 1898 when Marie and Pierre Curie purified it from barium using its radioactivity. They named it from the Latin word radius (meaning "ray") because the strength of its radioactivity was more than a million times that of uranium. Because of their metallic properties and low mass, Be and Mg are used to form lightweight alloys for structural purposes. Ca sees less industrial use, although the phosphate is sometimes utilized in fertilizers. Sr and Ba have no significant industrial applications. Both Be and Ra are used in various devices, the former because it is quite transparent to x-rays and the latter because it is a ready source of both α - and γ -radiation. Mg and Ca are essential to all living systems for many reasons; the other alkali earths have no known biological roles. see also Beryllium; Cesium; Curie, Marie Sklodowska; Davy, Humphry; Francium; Magnesium; Potassium; Rubidium; WÖhler, Friedrich. Michael E. Maguire Nechaev, I.; Jenkins, G. W.; and Van Loon, Borin (1997). Chemical Elements: The Exciting Story of Their Discovery and of the Great Scientists Who Found Them. Jersey City, NJ: Parkwest Publications. Rossotti, Hazel (1998). Diverse Atoms: Profiles of the Chemical Elements. New York: Oxford University Press. Winter, Mark (2003). WebElements Periodic Table, Scholar Edition. WebElementsLtd. Additional information available from .


From Yahoo Answers

Question:In other words, lets just say that I was to create a huge army of almost a million well-armored soldiers with this substance, what would it be? So plz don't mention things that are rare to find such as diamonds. They might be the hardest substance known to man, but supplying an army this big with protective gear made out of diamonds would be wayyyyyyyy too expensive. Of course, I 'm just using the whole "creating a huge army" thing as an example. Sorry it was the best example I could come up with.

Answers:Hardest metal alloy is a type of carbon steel, Alloy 1090. Carbon steel is surpassed in hardness only by very hard nonmetals, such as ruby, diamond, or aggregated diamond nanorods (ADNRs).

Question:

Answers:Lithium is the hardest alkali metal. http://www.speclab.com/elements/lithium.htm Not sure about alkaline earth, although I would think beryllium. However, radium has the highest density, so it would be the heaviest. That might not translate to hardness though. All the alkaline earth metals are pretty soft, and none are found free in nature, unlike the alkali metals. http://www.chemicalelements.com/groups/alkaline.html

Question:how do the properties of the lanthanide metals compare to those of the alkaline earth metals?

Answers:They have a valence of 2

Question:the word alkaline is a synonym for basic. why are the two words "alkaline" and "earth" used to name the group IIA metals?

Answers:Group 1 metals (Na,K, etc) are most commonly found dissolved in water. Group 2 metals (Ca, Mg, etc) are most commonly found in Carbonate minerals, such as Calcite (CaCO3) which makes up limestone. Carbonate minerals can be dissolved by acids, so are basic. That is how Group 2 became known as the alkaline earth metals, as they are most commonly found in alkaline rocks.

From Youtube

Alkaline and Alkaline Earth Metals :Properties of alkaline and alkaline earth metals and compounds.

Alkaline Earth Metals :