alkli metal

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IV. The Alkali Metals

The alkali metals are the family in Group of the periodic table. They are the elements lithium, , , rubidium, cesium, and francium. The name alkali comes from an Arabic word meaning ashes. Early chemists separated many sodium and potassium compounds from wood ashes. Hydroxides of the alkali metals are especially strong in basic, or properties.

Alkali metals have the that characterize metals in general. They are malleable, ductile, and lustrous, and they electricity and heat. As a group, however, the alkali metals have melting points than other metals, and they are so that they can easily be cut with a knife. In chemical reactions, atoms of these metals easily their single valence electrons. In fact, they are most family of metals.

Is the best known of the alkali metals. These metals show strong family resemblances. Thus, the method of preparing sodium in its elemental state and the properties of sodium are typical of all the alkali metals. Because of their

high activity, the alkali metals are not found in nature. sodium is prepared by the electrolysis of molten . Write down the equation: .

The free element is kept under to stop them reacting with air or water. Exposed to air, sodium quickly to form a film of sodium oxide. Left alone, the metal will oxidize .

Placed in water, sodium reacts violently, producing and hydrogen.

Going down the group, the alkali metals’ melting points , reactivity . The reason for both these trends is the same. The of the nucleus for the outer electron gets as the atoms get going down the group. So the atoms lose the outer electron more . Sodium is used in the preparation of titanium, a structural metal in aircraft engines and missiles. Sodium vapor lamps on highways and in parking lots help motorists see through thick fog. An alloy of sodium and potassium has a high heat conductivity and low melting point, properties that make it suitable as a coolant in nuclear reactors. Vast amounts of sodium chloride are found in and salt beds, from which sodium chloride is produced commercially. Sodium and potassium ions are present in human body fluids and play essential roles in physiology.

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