THE ALKALI METALS (Na & K)
• Occurance
• The alkali metals are too reactive to be found in the “free” state. Hence
are found in combination with other elements. Their ores usually contain
minerals that are soluble in aqueous solution known as →Type 1 ores
• Lithium is found in an alumino-silicate ore known as spodumene.
• Sodium occurs in rock salt, (NaCl) and chile saltpeter, (NaNO3).
• Potassium occurs in carnallite, (KCl) and saltpeter, (KNO3).
• Sodium and potassium are the most abundant alkali metals. Lithium, rubi
and cesium ores are more scarce thus these metals are more expensive.
Francium is radioactive.
, TRENDS OF THE ALKALI METALS
• Alkali metals are rather soft and they get softer on moving down
group. They have relatively low melting points, and their melting
points decrease on moving down the group.
• They are the most electropositive group and they become more
electropositive on moving down the group. As a result they have
ionization energies than other elements in the periodic table.
• They are very reactive, with reactivity increasing on moving down
group. They react to form high melting point, ionic compounds wh
tend to be water soluble. With a few exceptions, their compound
form colourless solutions.
• Occurance
• The alkali metals are too reactive to be found in the “free” state. Hence
are found in combination with other elements. Their ores usually contain
minerals that are soluble in aqueous solution known as →Type 1 ores
• Lithium is found in an alumino-silicate ore known as spodumene.
• Sodium occurs in rock salt, (NaCl) and chile saltpeter, (NaNO3).
• Potassium occurs in carnallite, (KCl) and saltpeter, (KNO3).
• Sodium and potassium are the most abundant alkali metals. Lithium, rubi
and cesium ores are more scarce thus these metals are more expensive.
Francium is radioactive.
, TRENDS OF THE ALKALI METALS
• Alkali metals are rather soft and they get softer on moving down
group. They have relatively low melting points, and their melting
points decrease on moving down the group.
• They are the most electropositive group and they become more
electropositive on moving down the group. As a result they have
ionization energies than other elements in the periodic table.
• They are very reactive, with reactivity increasing on moving down
group. They react to form high melting point, ionic compounds wh
tend to be water soluble. With a few exceptions, their compound
form colourless solutions.
