Alkaline-earth metal, any of the six chemical elements that comprise Group 2 (IIa) of the periodic table. The elements are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

Why are they called the alkali metals? The alkali metals are so named because when they react with water they form alkalies. Alkalies are hydroxide compounds of these elements, such as sodium hydroxide and potassium hydroxide. Alkalies react with acids to form salts.

Interesting Facts about Alkali Metals

• Because they are so reactive with air and water, they are generally stored in oil.
• Cesium and rubidium are used to make atomic clocks.
• Sodium and potassium both play an important role in biological life on Earth.
• Sometimes cesium is also spelled “caesium.”

1 : a soluble salt obtained from the ashes of plants and consisting largely of potassium or sodium carbonate broadly : a substance (such as a hydroxide or carbonate of an alkali metal) having marked basic properties — compare base sense 6a. 2 : alkali metal.

Strong alkalis include:

• sodium hydroxide.
• potassium hydroxide.

Uses of common Alkalis Sodium hydroxide is used to make paper, detergents and soap. Potassium hydroxide is used by farmers to make acidic soil more alkaline so that plants will grow better in it, and is also used as the electrolyte in alkaline, Ni-Cd, and Ni-MH batteries.

Common household alkalis include indigestion tablets (antacids), bleach, toothpaste, baking powder, cream cleaner, oven cleaner, metal polish and alkaline batteries.

Toothpaste is normally slightly alkaline, which neutralises the acids in your foods, and stops the enamel protecting your teeth from eroding and keeps your mouth at the correct pH for enzymes to work.

Alkaline Products Chlorine bleach is an alkaline solution of sodium hypochlorite dissolved in water.

Uses of Alkaline Earth Compounds Calcium compounds are widely found in limestone, marble, and chalk. Calcium is an important constituent of cement. Other uses include calcium chloride as a deicer and limestone as a white pigment in paints and toothpaste. Strontium is widely used in fireworks and magnets.

Of the six alkaline earth metals, beryllium, calcium, barium, and radium have at least one naturally occurring radioisotope; magnesium and strontium do not.

Beryllium

Several of the alkaline earth metals glow with a characteristic color when placed in a flame; calcium gives off an orange light, strontium a very bright red, and barium an apple green. These flame tests are useful for identifying the metals.

least soluble in water is Be(OH)2​ Was this answer helpful?

calcium

Thus, Ca has the least density.

Mg

lithium

beryllium

The alkaline earth metals are denser than the alkali metals due to smaller size and better backing in the crystal lattice. The densities of alkaline earth metal do not show any regular trend with increasing atomic number. The density of these metal first decreases from Be to Ca and then increases from Ca to Ba.

So, the order of density is down the group at first decreases then increases. Note:According to periodic properties of the elements of the second period (Li, B, Be) and third period (Mg, Al, Si) elements which are diagonally present with each other in the periodic table, show some similar kind of chemical properties.

The first chemical element with the lowest density is Hydrogen and the highest density is Osmium.

Alkaline Earth metals are very reactive because they readily give up their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. Reactivity increases from the top to the bottom of the group.