C2.3 - Group 1 - Alkali metals. Flashcards
Properties of alkali metals
-very reactive
-reactivity increases as you move down the group
-low density (floats on water)
-soft
-silvery shiny surface when cut, then darkens as it oxidises
Why are alkali metals stored in oil?
To prevent them from reacting with oxygen as they are very reactive elements.
Reactivity of alkali metals - shielding effect
-atoms increase in size as you go down the group
-so outershell moves further away from the nucleus
-becomes shielded by inner electrons
-the further away it is from the nucleus the easier it is to lose and becomes more reactive
How lithium reacts with water (4 points)
-floats on water
-fizzes
-moves around
-decreases in size
How sodium reacts with water (6 points)
-floats on water
-moves around
-fizzes
-produces an orange flame
-forms a ball
-decreases in size
How potassium reacts with water (4 points)
-floats on water
-fizzes
-lilac flame
-decreases in size
Word equation for reaction of alkali metals and water
Lithium + water -> lithium hydroxide + hydrogen
What do alkali metals produce when reacting with water
-an alkali solution
-aka a hydroxide
Balanced equation of alkali metal + water
2Li + 2 H2O -> 2LiOH + H2
Word equation of alkali metal and oxygen reaction
Lithium + oxygen –> lithium oxide
Formula for lithium and oxygen reaction
Li + o2 –> Li2O
Balanced equation for alkali metal and oxygen reaction
4Li + O2 —> 2Li2O
