group 1 metals Flashcards
why are group 1 metals known as the alkali metals
because they form alkaline solutions when they react with water
the alkali share these properties
They are all soft metals which can easily be cut with a knife
They have relatively low densities and low melting points
They are very reactive (they only need to lose one electron to become highly stable)
general pattern for group 1 elements reacting with water
group 1 metal + water ⟶ metal hydroxide + hydrogen
the reactions with alkali metals and water get
more vigorous as you descend the group
the alkali metals react with oxygen in the air forming
metal oxides
the metal oxide produced is
a dull coating which covers the surface of the metal- the metal tarnish more rapidly as you go down the group
trend in physical properties across the alkali metals
The alkali metals are soft and easy to cut, getting softer as you move down the group
The first three alkali metals are less dense than water
They all have relatively low melting points which decrease as you move down the group, due to decreasing attractive forces between outer electrons and positive ions
reaction with air and water in group 1
Rubidium, caesium and francium will react even more vigorously with air and water than the first three alkali metals
what is the least reactive group 1 metal
lithium
predicted properties of rubidium
would be a soft grey solid
appears shiny when freshly cut
is more dense than potassium (> 0.86 g cm-3)
has a lower melting point than potassium (< 63.5 oC)
