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A basic oxide, also called a base anhydride (meaning "base without water"), is usually formed in the reaction of oxygen with metals, especially alkali (group 1) and alkaline earth (group 2) metals. Both of these groups form ionic oxides that dissolve in water to form basic solutions of the corresponding metal hydroxide: Alkali metals (Group 1)
Although most metal oxides are crystalline solids, many non-metal oxides are molecules. Examples of molecular oxides are carbon dioxide and carbon monoxide. All simple oxides of nitrogen are molecular, e.g., NO, N 2 O, NO 2 and N 2 O 4. Phosphorus pentoxide is a more complex molecular oxide with a deceptive name, the real formula being P 4 O 10.
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Lithium oxide (Li 2 O) is the lightest alkali metal oxide and a white solid. It melts at 1570 °C. Sodium oxide (Na 2 O) is a white solid that melts at 1132 °C and decomposes at 1950 °C. It is a component of glass. Potassium oxide (K 2 O) is a pale yellow solid that decomposes at 350 °C. Rubidium oxide (Rb 2 O) is a yellow solid that melts ...
Oxides. The alkaline earth metal oxides are formed from the thermal decomposition of the corresponding carbonates. CaCO 3 → CaO + CO 2 (at approx. 900°C) In laboratory, they are obtained from hydroxides: Mg(OH) 2 → MgO + H 2 O. or nitrates: Ca(NO 3) 2 → CaO + 2NO 2 + 1/2O 2. The oxides exhibit basic character: they turn phenolphthalein ...
Carbonic acid is an illustrative example of the Lewis acidity of an acidic oxide. CO 2 + 2OH − ⇌ HCO 3 − + OH − ⇌ CO 3 2− + H 2 O. This property is a key reason for keeping alkali chemicals well sealed from the atmosphere, as long-term exposure to carbon dioxide in the air can degrade the material.
Metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides. Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Aluminium oxide (Al 2 O 3) is an example of an amphoteric oxide. Amphoterism depends on the oxidation states of the oxide ...
The oxides of elemental metals are often basic. However, oxides with very high oxidation states such as CrO 3, Mn 2 O 7, and OsO 4 often have strictly acidic reactions; and oxides of the less electropositive metals such as BeO, Al 2 O 3, and PbO, can display both basic and acidic properties.