Topic 4 - Elements

A substance containing only one type of atom

• shiny • malleable, ductile • conduct electricity and heat well • high melting points • high density • hard

• dull appearance • not malleable or ductile • conduct electricity and heat badly • low melting point • low density • brittle

Bromine Oxygen Chlorine Iodine Hydrogen Astatine Nitrogen Fluorine

Nitrogen - 78% Oxygen - 21% Argon - 1% Carbon dioxide - 0.04%

1) Fill a gas syringe will 100cm3 of air and pass it across heated phosphorus in the centre to an empty gas syringe 2) the oxygen in the air reacts with the phosphorus, so the volume left over is everything in the air excepting oxygen

1) soak some iron wool in acetic acid (to catalyse the reaction). Then push the wool into a measuring cylinder and invert the measuring cylinder into a beaker of water 2) record the starting position of the water using the scale on the measuring cylinder - this is the starting volume of air 3) over time, the level of the water in the measuring cylinder will rise 4) this is because the Ron reacts with the oxygen the air to make iron oxide- the water rises to fill the space which the water took up 5) leave the measuring cylinder for around a week or until the water level stops changing 6) record the finishing position of the water - this is the final volume of air 7) calculate percentage by subtracting the final volume from the initial volume, dividing by the start volume and multiplying by 100

Put H202 (hydrogen peroxide) in a conical flask with the catalyst MnO2 (manganese IV oxide) Bung the top of a conical flask and run a delivery tube from inside the conical flask to an upside down test tube that is underwater to collect the O2 Equation: 2H202 -> 2H20 + O2

Glowing splint relights

Oxygen + element -> element oxide

Equation: 2Mg(s) + 02(g) -> MgO (s) Observations: bright white flame, white powder formed (which is slightly alkaline when dissolved in water)

Equation: S(s) + O2 (g) -> SO2 (g) Observation: pale blue flame Sulphur dioxide is acidic when dissolved in water

2H2(g) + O2(g) -> 2H2O(g) • burns very easily, can be explosive, squeaky pop • orangey/yellow flame

They are basic

They are acidic

Nitrogen oxides and sulphur dioxides released by fuel combustion

• makes water bodies acidic, killing aquatic life • damages buildings, corrodes limestone • damages waxy cuticles of trees, making it more difficult for them to absorb nutrients