2 A,B,C,D Flashcards
Group 1 alkali metals
Lithium, sodium, potassium
Understand how the similarities in the reactions of these elements with water provide evidence for the recognition as a family of elements
fizzing (hydrogen is produced)
metal floats and moves around on the water
metal disappears
In each case a metal hydroxide solution is produced.
Act vigorously with water
These similarities in the reactions provide evidence that the 3 metals are in the same group of the Periodic Table (i.e. have the same number of electrons in their outer shell).
Understand how the differences between the reactions of these elements with air and water provide evidence for the trend in reactivity in group 1
Lithium: less reactive
fizzing (hydrogen gas is released)
lithium floats and moves around on the water
lithium disappears
Sodium: median reaction fizzing (hydrogen gas is released) sodium floats and moves around on the water sodium melts into a silver-coloured ball sodium disappears
Potassium: the most reactive fizzing (hydrogen gas is released) potassium floats and moves around on the water catches fire with a Lilac flame potassium disappears
When the group 1 metals react with air they oxidise, showing a similar trend in reactivity as we go down the group of the Periodic Table.
Use knowledge of trends in group 1 to predict the properties of other alkali metals
As the reactivity of Alkali Metals increases down the Group, Rubidium, Caesium and Francium will react more vigorously with Air and Water
Lithium is at the top so will be the least reactive, while Francium is at the bottom so will be the most reactive (Francium is rare and radioactive so is difficult to confirm predict reaction)
Rubidium- explodes with sparks
Caesium- violent explosion due to rapid production of heat and hydrogen
Francium- too reactive
Group 7 Halogens
F2. Cl2 Br2 I2 At2
Use knowledge of trends in group 7 to predict the properties of other halogens
As you go down the group: Colour becomes darker From gas it turns to solid Melting and boiling point increases The reactivity decreases
Understand how displacement reactions involving halogens and halides provide evidence for the trend in reactivity in group 7
A more reactive halogen will displace a less reactive halogen, e.g. chlorine will displace bromine
By reacting a halogen solution with a potassium halide solution and making observations, the order of their reactivity can be deduced
Top layer: pink - I2
Top layer: orange - Br2
Top layer: colourless - Cl2
When one of the halogens goes alone they always have a (small)2 next to them.
Oxidation is loss of electrons.
Reduction is gain of electrons.
Gases in the atmosphere
Nitrogen Oxygen Argon Carbon dioxide Water vapour
Know the approximate percentages by volume of the four most abundant gases in dry air.
Nitrogen, N2 - 78%-79% Oxygen, O2 - 20%-21% Argon, Ar - 1% (approx.) Carbon dioxide, CO2 - 0.03 (approx.) Water vapour, H2O variable amounts
Understand how to determine the percentage by volume of oxygen in air using experiments involving the reactions of metals (e.g. iron) and non-metals (e.g. phosphorus) with air
- Copper:
The copper is in excess and uses up the oxygen to form copper oxide (CuO).
All the oxygen in the air is therefore used up, and so the volume of the air decreases by about 20% (the percentage of oxygen in air).
Copper + oxygen - copper oxide
2Cu + O2 - 2CuO
- Iron:
The iron reacts with the oxygen in the air (rusting).
As long as the iron and water are in excess, the total volume of air enclosed by the apparatus decreases by about a fifth (20%) over several days.
Iron + Oxygen + Water - hydrated iron (III) oxide (rust)
- Phosphorus:
The phosphorus is lit with a hot wire.
It reacts with the oxygen in the air and causes the water level in the bell jar to rise by about 20%.
Phosphorus + oxygen - Phosphorus oxide
Describe the combustion of elements in oxygen, including magnesium, hydrogen and sulphur
- Magnesium reacts with oxygen producing a bright white flame leaving behind a white ash of magnesium oxide.
Magnesium + oxygen → Magnesium oxide 2Mg (s) + O₂ (g) → 2MgO
MgO is a base, which can react with an acid to give a salt and water.
- Hydrogen reacts with oxygen in an explosive reaction. This is the basis of the ‘squeak pop’ test for hydrogen in test tube. With larger quantities of hydrogen this explosion can be dangerous.
hydrogen + oxygen → water 2H₂ (g) + O₂ (g) → 2H₂O (l)
- Sulfur reacts with oxygen producing a blue flame.
sulfur + oxygen → sulfur dioxide S (s) + O₂ (g) → SO₂ (g)
When sulfur dioxide (SO₂) dissolves in water it forms an acidic solution of sulfurous acid:
SO₂ (g) + H₂O (l) Sulfur reacts with oxygen producing a blue flame.
sulfur + oxygen → sulfur dioxide
S (s) + O₂ (g) → SO₂ (g)
Describe the formation of carbon dioxide from the thermal decomposition of metal carbonates, including copper (II) carbonate
In thermal decomposition a compound is broken down into simpler compounds by the action of heat.
Eg- CuCO3(s) → CuO(s) + CO2(g)
Green. Black
Observation: green powder (CuCO3) changes to a black powder (CuO)
Know that carbon dioxide is a greenhouse gas and that increasing amounts in the atmosphere may contribute to climate change
Carbon dioxide (CO2) is a greenhouse gas.
It absorbs infra-red radiation and therefore warms the atmosphere. This leads to global warming.
This may cause climate change.
Explanation:
Sun emits short wave radiation (ultraviolet radiation) that enters the Earth’s atmosphere
Earth’s surface absorbs short wave radiation from the sun and re-emits it as long wave radiation (infrared/heat)
Greenhouse gases - such as Carbon Dioxide, absorb and re-radiate this long wave radiation, retaining heat within the atmosphere
Earth’s average temperature rises as a result
Practical: determine the approximate percentage by volume of oxygen in air using metal or non-metal
The same as the copper, iron and phosphorus
Reactivity series
Potassium Sodium Lithium Calcium Magnesium Aluminium (Carbon) Zinc Iron Tin Lead (Hydrogen) Copper Silver Gold Platinum
