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Alkali Metals. By Ayaana Patel Sikora. What are Alkali Metals?.
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Alkali Metals By Ayaana Patel Sikora
What are Alkali Metals? • The alkali metals are located in Group 1 of the periodic table. They are a series of chemical elements which have similar trends and properties. Alkali metals are so called because when they react with water alkalis (strong bases that can neutralize acids) are formed.
Elements • The elements in Group 1 of the periodic table – alkalis – are • 1) Lithium • 2) Sodium • 3) Potassium • 4) Rubidium • 5) Caesium • 6) Francium
Physical Properties • The physical properties of alkali metals are very similar with other metallic elements. However, there are many differences as well. • Alkali metals are mostly silver colored, with the exception of Caesium, which has a golden tint. • Alkali metals are all soft metals of low densities (they are very light) and low boiling and melting points. • Alkali metals are good conductors of heat and electricity. • They are lustrous and ductile and have malleable properties. • Alkalis also have a bitter taste and a soapy touch.
Chemical Properties • Alkalis have one electron in their outermost shell – for example, Lithium had an electronic configuration of 2,1 and sodium has an electronic configuration of 2,8,1. By looking at the outermost shell of an element we can tell whether or not it belongs to the Group 1 alkalis. • Another chemical property of alkalis is that the reactivity increases as you go down the group. • The alkali metals have the lowest ionization potentials (i.e. they have a high electropositivity)
Reactivity • Alkalis are extremely reactive and never found in elemental forms in nature. They are usually stored in paraffin oil (kerosene) or mineral oil. • All of the alkali metals react aggressively with the halogens to form ionic salts.
Reactions with Water • The chemical equation of the reaction between an alkali and water is -Alkali metal + water = alkali metal hydroxide + hydrogen gas. When Francium and Caesium react with water they explode and the reaction is extremely vigorous.
Reaction with Oxygen • When an alkali reacts with oxygen it starts burning and oxides are formed. At the end of the chemical reaction, the alkali metals give off superoxide (each alkali metal atom forms bonds with two oxygen atoms)
Reaction with Chlorine • Reaction with chlorine –If you put heated alkali metals into jars of chlorine gas they will burst into a flame and burn brightly giving white solids called chlorides.