What group are the alkali metals in?
What are the properties of the Alkali metals?
- they are very reactive
- soft to cut
- they are stored in oil
- the outside of them are dull ( such as a non metal )
- when you cut into them they are silver and shiny ( like a metal )
Why are they sorted under oil?
because they are very reactive and react with water and oxygen
What happens to them as you go down the elements?
- they become more reactive
- they become softer
- the melting points decrease
Reaction with oxygen
When alkali metals are left in oxygen the surface will tarnish ( go dull )
Example of reaction :
Lithium + oxygen --> Lithium oxide
Li + O2 --> Li20
Reaction with water
They all have the same reactions and extras:
- movers across the surface of the water
- melts when hits the water and turns into a sphere ( ball )
- Catches a lilac flame
- spits at the end
reaction with water equation
Sodium + water --> Sodium hydroxide + Hydrogen
Na + H20 ---> NaOH + H2
What group are the halogens in?
What are unique about the halogens?
They go round in pairs
' Diatomic Molecules '
what happens as you do down the halogens?
- their melting and boiling points increase
- their reactivity decreases
- they become darker in colour
reaction with group 1 metals
example of when a halogen reacts with an alkali metal
lithium + fluorine --> lithium fluoride
2Li + F2 --> 2LiF
Reaction with iron
Fluoride is very reactive, iron burst into flames without being heated
iron and chlorine react fiercely, iron is heated first
iron and bromine react, this reaction has to be heated
iodine reacts with iron, has to be heated strongly
Compounds like sodium chloride, potassium iodide are called salts, they are made up of crystals
the first name of a salt is always a metal ( positive ion )
the surname is always a non metal ( negative ion )
Testing for metal ions ( flame test )
- dip a piece of nichrome or platinum wire into the salt
- place into the hottest part of a blue flame #
- look carefully at the flame and observe the colour change
the results of the flame test
contains sodium the flame goes orange/yellow
contains potassium the flame goes lilac/pink
contain lithium goes scarlet red
testing for chlorides bromides and iodides
- place a small spatula of the salt into a test tube
- add a pipette of diluted nitric acid
- shake the test tube
- add a pipette of silver nitrate solution
results of chlorides bromides and iodides
white precipitate for chloride
cream precipitate for bromide
pale yellow precipitate for iodide