The atomic number of an atom is the number of ________________
Protons
The mass number of an atom is the number of __________________
Protons plus neutrons
Explain why an atom has no overall charge.
Because the number of positive protons is equal to the number of negative electrons
Explain why flourine and chlorine are in the same group of the periodic table.
Flourine: 2,7 Chlorine: 2,8,7 , same group because they have the same number of electrons in their outer shell
What is the chemical symbol of this non metal?
S
Compounds formed when non-metals react with metals consist of particles called ______________
Ions
Compounds formed from only non-metals consist of particles called ______________
Molecules
The main compound in limestone is calcium ________________
Carbonate
The reaction to produce calcium oxide from limestone is thermal _____________
Decomposition
Calcium hydroxide is produced when calcium oxide reacts with _____________
Water
Calcium hydroxide is used to neutralise acids because it is an ______________
Alkali
Describe one way the students could improve the method so that their results are more accurate for each graph point.
Repeat the experiment and calculate a mean
What force is needed to break a concrete beam containing no aggregate?
34-40
The students conclusion is not completely correct. Use values from the graph to explain why.
At first, the force needed to break a concrete beam increases but the force needed to break a concrete beam then decreases. 400g point of change.
Why are there many theories of how life was formed on earth?
Not enough evidence, formed billions of years ago.
Describe and explain how the surface of the early earth and its atmosphere have changed to form the earth today.
Oxygen increased because plants developed and used CO2 for photosynthesis, decreasing it. CO2 decreased because oceans formed and dissolved CO2. Oceans formed because water vapour cooled and condensed. Continents formed because the earth cooled forming a
Explain why stage 2 has to be done.
To remove impurities and compounds need to be separated.
Cast iron is not suitable for the manufacture of pylons. Why?
It is brittle.
How is cast iron converted into steel?
The oxygen reacts with carbon, reducing the % of carbon in the mixture/ producing CO2.
State one property that makes aluminium more suitable than copper for overhead cables.
Aluminium has a low density
Where are the transition metals on the periodic table?
In the central block. Aluminium is in group 3.
Copper can be extracted from solutions of copper salts by adding iron. Why?
Iron is more reactive than copper so copper is displaced.
Describe how crude oil is separated into fractions.
Crude oil is heated to vaporise the hydrocarbons. The column is hotter at the bottom than the top. The fractions condense at their boiling points.
Suggest how the use of a suspension of limestone decreases one of the environmental impacts that the waste gases would cause.
Acid rain is caused by sulfur dioxide, they are neutralised by the limestone.
Third one?
C2H4
Show polypentene.
Copy thingy.
Suggest one property of a smart polymer that is different to that of an ordinary polymer.
Has a shape memory.
Give one reason why vegetable oils are important foods and fuels.
They provide energy.
State the two main stages used to extract a sample of vegetable oil from seeds.
Crushing, pressing.distillation
Give one property of a vegetable oil which gives the oil an advantage over water for cooking foods.
Vegetable oils have a higher boiling point than water so foods are cooked faster.
Explain how the emulsifier molecules are able to produce an emulsion that is a stable mixture containing the vegetable oil and water.
The emulsifier molecules have a hydrophilic head which is attracted to water and a hydrophobic tail which is attracted to oil. This forms a suspension of oil in water.