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The alkaline earth metals (Be, Mg, Ca, Sr, Ba, and Ra) are the second most reactive metals in the periodic table, and, like the Group 1 metals, have increasing reactivity with increasing numbers of energy levels. Beryllium (Be) is the only alkaline earth metal that does not react with water or steam, even if the metal is heated red hot. [9]
It ignites spontaneously in air, and reacts explosively with water even at low temperatures, more so than the other alkali metals. [14] It reacts with ice at temperatures as low as −116 °C (−177 °F). [17] Because of this high reactivity, caesium metal is classified as a hazardous material.
A polar molecule has a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically. Water (H 2 O) is an example of a polar molecule since it has a slight positive charge on one side and a slight negative charge on the other. The dipoles do not cancel out ...
Plutonium is a reactive metal. In moist air or moist argon, the metal oxidizes rapidly, producing a mixture of oxides and hydrides. [5] If the metal is exposed long enough to a limited amount of water vapor, a powdery surface coating of PuO 2 is formed. [5] Also formed is plutonium hydride but an excess of water vapor forms only PuO 2. [41]
Finely powdered potassium ignites in air at room temperature. The bulk metal ignites in air if heated. Because its density is 0.89 g/cm 3, burning potassium floats in water that exposes it to atmospheric oxygen. Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse.
When finely powdered, magnesium reacts with water to produce hydrogen gas: Mg(s) + 2 H 2 O(g) → Mg(OH) 2 (aq) + H 2 (g) + 1203.6 kJ/mol. However, this reaction is much less dramatic than the reactions of the alkali metals with water, because the magnesium hydroxide builds up on the surface of the magnesium metal and inhibits further reaction ...
Many metal and nonmetal sulfides, e.g. aluminium sulfide, phosphorus pentasulfide, silicon disulfide liberate hydrogen sulfide upon exposure to water: [28] 6 H 2 O + Al 2 S 3 → 3 H 2 S + 2 Al(OH) 3 This gas is also produced by heating sulfur with solid organic compounds and by reducing sulfurated organic compounds with hydrogen.
In aqueous solution the water molecules directly attached to the metal ion are said to belong to the first coordination sphere, also known as the first, or primary, solvation shell. The bond between a water molecule and the metal ion is a dative covalent bond , with the oxygen atom donating both electrons to the bond.