Alkaline earth metals

Examples of Alkaline earth metals in the following topics:

• The Alkaline Earth Metals

  • The alkaline earth metals comprise the group 2 elements.
  • All the discovered alkaline earth metals occur in nature.
  • In chemical terms, all of the alkaline metals react with the halogens to form ionic alkaline earth metal halides.
  • The heavier alkaline earth metals react more vigorously than the lighter ones.
  • Emerald is a variety of beryl, a mineral that contains the alkaline earth metal beryllium.

• Strong Bases

  • Common examples of strong Arrhenius bases are the hydroxides of alkali metals and alkaline earth metals such as NaOH and Ca(OH)2.
  • The cations of these strong bases appear in the first and second groups of the periodic table (alkali and earth alkali metals).
  • Generally, the alkali metal bases are stronger than the alkaline earth metal bases, which are less soluble.
  • Usually, these bases are created by adding pure alkali metals in their neutral state, such as sodium, to the conjugate acid.

• Nature of Acids and Bases

  • Most alkali metal and some alkaline earth metal hydroxides are strong bases in solution.
  • The alkali metal hydroxides dissociate completely in solution.
  • The alkaline earth metal hydroxides are less soluble but are still considered to be strong bases.

• Binary Hydrides

  • Ionic, or saline, hydride is a hydrogen atom bound to an extremely electropositive metal, generally an alkali metal or an alkaline earth metal (for example, potassium hydride or KH).
  • Classical transition metal hydrides feature a single bond between the hydrogen center and the transition metal.
  • Interstitial hydrides most commonly exist within metals or alloys.
  • Their bonding is generally considered metallic.
  • Such bulk transition metals form interstitial binary hydrides when exposed to hydrogen.

• Metallic Crystals

  • Metallic crystals are held together by metallic bonds, electrostatic interactions between cations and delocalized electrons.
  • These interactions are called metallic bonds.
  • Atoms in metals are arranged like closely-packed spheres, and two packing patterns are particularly common: body-centered cubic, wherein each metal is surrounded by eight equivalent metals, and face-centered cubic, in which the metals are surrounded by six neighboring atoms.
  • Some metals (the alkali and alkaline earth metals) have low density, low hardness, and low melting points.
  • The high density of most metals is due to the tightly packed crystal lattice of the metallic structure.

• Oxides

  • Most of the Earth's crust consists of solid oxides, the result of elements being oxidized by the oxygen in air or water.
  • In part for this reason, alkali and alkaline earth metals are not found in nature in their metallic form.
  • Metals tend to form basic oxides, non-metals tend to form acidic oxides, and amphoteric oxides are formed by elements near the boundary between metals and non-metals (metalloids).
  • Metal oxides can be reduced by organic compounds.
  • Silicon dioxide (SiO2) is one of the most common oxides on the surface of earth.

• Electron Configurations and Magnetic Properties of Ions

  • The alkali metals and alkaline earth metals have one and two valence electrons (electrons in the outer shell), respectively; because of this, they lose electrons to form bonds easily and so are very reactive.
  • The p block, on the right, contains common non-metals, such as chlorine and helium.
  • The halogens, directly to the left of the noble gases, readily gain electrons and react with metals.
  • The d block, which is the largest, consists of transition metals, such as copper, iron, and gold.
  • The f block, on the bottom, contains rarer metals, including uranium.

• General Trends in Chemical Properties

  • Moving left to right across a period, from the alkali metals to the noble gases, atomic radius usually decreases.
  • Electron affinity also shows a slight trend across a period: metals (the left side of a period) generally have a lower electron affinity than nonmetals (the right side of a period), with the exception of the noble gases which have an electron affinity of zero.
  • The s block includes the first two groups (alkali metals and alkaline earth metals) as well as hydrogen and helium.
  • The d block includes Groups 3 to 12 in IUPAC (or 3B to 2B in American group numbering) and contains all of the transition metals.

• Variation of Physical Properties Across a Period

  • All Group 1 metals form halides that are white solids at room temperature.
  • All of the alkali halides and alkaline earth halides are solids at room temperature and have melting points in the hundreds of degrees centigrade.
  • The non-metal halide liquids are also electrical insulators and do not conduct electrical current.
  • In contrast, when an alkali halide or alkaline earth halide melts, the resulting liquid is an excellent electrical conductor.
  • This tells us that these molten compounds consist of ions, whereas the non-metal halides do not.

• Soaps & Detergents

  • Alkali metal salts of fatty acids are more soluble in water than the acids themselves, and the amphiphilic character of these substances also make them strong surfactants.
  • Solutions of alkali metal soaps are slightly alkaline (pH 8 to 9) due to hydrolysis.
  • Also the sulfonate functions used for virtually all anionic detergents confer greater solubility on micelles incorporating the alkaline earth cations found in hard water.