2.3 group 1 - the alkali metals Flashcards
Alkali metals def
Elements in group 1 of the periodic table
Why do alkali metals have to be stored in oil?
To stop them reacting with oxygen in the air
Does reactivity increase or decrease going down the group
Increase
What are the physical properties of alkali metals?
- Very low density compared to other metals. Lithium, sodium and potassium can float on water
- Soft and and be cut with a knife
- Shiny surface when cut
- In a jar of oxygen has, hot alkali metals burn vigorously, forming a white smoke of their oxides
Why does the alkali metal quickly go dull after it’s been cut?
Because it’s reacting with oxygen and a layer of oxide forms on the surface
Why are group 1 elements so reactive?
Because they only need to lose 1 electron in their outermost shell to get the stable electronic structure of a noble gas
How do group 1 elements react with non-metals?
They form a metal ion carrying a 1+ charge. They always from ionic compounds
Do melting and boiling points increase or decrease going down group 1?
Decrease
What are the reactions of lithium, sodium or potassium with water?
Metal floats on the water, moving around and fizzing. It fizzes because metal reacts with water to form hydrogen gas
How does potassium burn in water?
It burning with a lilac flame, coloured by the potassium ions formed in the reaction. The reaction between an alkali metal and water also produces a metal hydroxide. Solution is colourless with a high pH.
Why do chemical reactions get more and more vigorous going down the group?
Because it becomes easier to lose the single electron in the outer shell to form ions with a 1+ charge
How do alkali metals react with chlorine, bromine, fluorine and iodine?
They produce metal -ides, which are white solids. They all dissolve easily in water to form colourless solutions
