Group 1 - the alkali metals Flashcards
which group are the alkali metals in?
group 1
what are the physical properties of alkali metals? (2)
-are soft (they can be cut with a knife)
-have relatively low melting points
what do alkali metals also have in terms of mass?
-how does this affect the first three alkali metals?
low densities.
- (lithium, sodium and potassium) can float on water.
what happens to the melting point of the alkali metals as you go down the group? (2)
-their melting point decreases
-the difference in melting point decreases going from one element to the next
what do alkali metals react with water to produce?
alkali metal + water → metal hydroxide + hydrogen
what is metal hydroxide in terms of pH?
-if dissolved in water, what would this form?
-an alkali
-a base that dissolves in water to form an alkaline solution
what happens with very reactive metals when the hydrogen is produced?
-the energy of the reaction causes the hydrogen to burn as the reaction takes place.
what happens to the reactivity of the metals as you go down the group?
the reactivity of these metals increases going down the group
what would you see when lithium reacts with water? (2)
-Fizzes steadily
-slowly becomes smaller until it disappears
what would you see when sodium reacts with water? (2)
-Melts to form a ball, fizzes rapidly
-quickly becomes smaller until it disappears
what would you see when potassium reacts with water? (3)
-Quickly melts to form a ball,
-burns violently with sparks and a lilac flame,
-disappears rapidly (often with a small explosion)
why does the reactivity of group 1 elements increases as you go down the group? (4)
-atoms become larger
-outer electron becomes further from the nucleus
-force of attraction between the positive nucleus and the negative outer electron decreases
-outer electron is lost more easily
