C4

Metal + Oxygen = ? (and observation)

Metal + Oxygen = metal oxide Potassium + Oxygen = Potassium oxide
The metal tarnishes or goes dull as they react with the oxygen in the air.

Metal + Water = ? (and observation)

Metal + water = Metal hydroxide + hydrogen
Potassium + water = Potassium hydroxide + hydrogen
Fizzing, melt into a ball, floating on water, Potassium bursts into a lilac flame and sodium bursts into an orange/yellow flame

Metal + Halogen = ? (and observation)

Metal + Halogen = Metal Halide (salts)
Potassium + Chloride = Potassium Chloride
Group 1 metal halides are white crystalline salts but colourless in water

Why does reactivity increase as you go down group 1?

Size of the atom increases because there are more shells. The shielding increases so the nuclear attraction on the last shell electron gets weaker. It becomes easier to lose the lost shell electron, increasing reactivity.

Chemical and physical properties of Alkali Metals/group 1 metals

They are soft and can be cut with a knife
Low melting point
low density
Malleable and ductile
Chemical property- high reactivity with oxygen and water

Physical properties of Halogens/group 7 elements

Diatomic molecules (Cl2)
Low melting point because weak intermolecular forces
As you go down group, boiling point increases because size of molecule increases so intermolecular forces increase as there is more. More energy needed to break them.

Physical properties of chlorine, bromine, iodine and their colour in water

Chlorine- Yellow gas. Yellow/Green in water
Bromine- Red, Brown liquid. Orange/brown in water
Iodine- Grey solid. Brown in water

Why does reactivity decrease as you go down group 7?

The size of the atom increases because there are more shells.
Shielding increases so nuclear attraction on the incoming electron gets weaker
It becomes harder to gain an electron into its last shell.

When will a halogen cause a displacement reaction?

A more reactive halogen will displace a less reactive halogen from its compound in solution
eg. Chlorine will displace Bromine from Sodium Bromide and create Sodium Chloride

Properties of Transition metals

Form more than one ion (eg. Fe2+ Fe3+)
Form coloured compounds
Can be used as catalysts along with their compounds
High density (they’re hard) and High melting point
Low reactivity with water and oxygen

Physical properties of noble gases (group 0)

Unreactive as they have a full outer shell- do not share, gain or lose electrons
Monoatomic- Low boiling point
Colourless gases and they are all gases

Trend of boiling points in group 0

As you go down the group, boiling point increases because the relative molecular mass increases so there are stronger intermolecular forces so they require more energy to break.

Uses of noble gases

Helium- Used in ballooons and airships as has lower density than air
Neon- advertising signs
Argon- Filament lamps and bulbs

Uses of transition metals

Copper used in wires and saucepans
Gold used in jewellery
Iron used in car bodies

Testing for gases and their observations (Hydrogen, CO2, Oxygen, Chlorine)

Hydrogen test- place a lit splint next to gas. Should hear a squeaky pop
Carbon dioxide test- Bubble gas in colourless limewater. The limewater should go cloudy if present
Oxygen test- A glowing splint will relight
Chlorine test- bleaches damp red or blue litmus paper

Describe the flame test to test for metal ions

Clean the nichrome wire in HCl (hydrochloric acid) to avoid contamination
Place the wire in the metal ion solution and place the wire in the blue part of the flame and observe the colour change

Each metal ion and the flame they create

Lithium- Crimson red
Sodium- Yellow
Potassium- lilac
Copper (2+)- blue/green
Barium (2+)- apple green
Calcium (2+)- orange/red

Describe the precipitate reaction to test for metal ions

React the metal ion solution with NaOH solution (Sodium Hydroxide). The colour of the precipitate is used to identify the metal ions.

Each metal ion and their precipitate colour

Copper (2+)- Blue
Iron (2+)- green
Iron (3+)- orange/brown
Calcium (2+) AND magnesium (2+)- white
Zinc (2+)- white but dissolves when excess NaOH added

Test for Carbonate ions (CO3)2-

Place some hydrochloric acid in a test tube and add a small spatula of the solid ionic compund. Look for bubbles of gas. If a gas is released, insert a delivery tube into the test tube and bubble the gas through limewater. If there are Carbonate ions, the limewater will go cloudy.

Test for Sulphate ions (SO4)2-

Dissolve a small amount of the solid ionic compound in deionised water. Then add a few drops of hydrochloric acid followed by barium chloride solution. If sulphate ions present, a white precipitate is formed.

Halide ion test

Dissolve a small amount of the solid ionic compound in deionised water. Then add a few drops of nitric acid followed by silver nitrate solution. Colour of precipitate formed tells you which halide ion present

Halide ion test results

If Chloride ions present- white precipitate is formed
If bromide ions present- cream precipitate formed
If iodide ions present- yellow precipitate formed

Advantages and disadvantages of instrumental analysis

Advantages- Very accurate and precise, It is quick (automated process), Very sensitive (little sample needed)
Disadvantages- very expensive

What does gas chromatography show?

Number of compounds in the mixture (number of peaks)
Amount of each compound (height of the peak)
Retention time (position of the peak)

What does a mass spectrometer show?

Used to measure the relative atomic mass of atoms and molecules
Analyse relative amounts of different isotopes of an element and structure of organic molecules.
Each peak represents a different fragment of the molecule
The molecular ion peak is furthest to the right and it is the relative mass of the molecule