Chemistry 4, 5, 6 Questions Flashcards
What’s the mass of an electron?
0.0005/0
What is the charge of a neutron?
No charge
What is the charge of an electron?
Negative
What is the mass of a neutron?
1
What is the mass of a proton?
1
What is the atomic number?
The amount of protons in an atom
What is the mass number?
The amount of protons and neutrons in an atom
What group will an element with the electronic configuration 2,8,8 be in?
Group 0
What group will an element with an electronic configuration 2,8,2 be in?
Group 2
What did JJ Thompson discover?
He discovered the electrons
What did Ernest Rutherford discover?
He discovered that atoms have a central nucleus
What did Niels Bohr discover?
He developed the idea of Rutherford and said that electrons occupy particular shells around the nucleus of an atom.
What are isotopes?
They have the same atomic number but different mass numbers
The elements in the periodic table are arranged in order of increasing what?
Proton number
How many electrons does an element of 2,8,5 have?
15
Why do simple molecular substances have weak intermolecular bonds?
Their melting and boiling points are very low, because the molecules are easily parted from each other.
What are the group one metals also known as?
The alkali metals
As you go down group one, what happens to the elements?
They become more reactive because the outer electron is further away from the nucleus, so less energy is needed to remove it.
What are the group 7 elements also known as?
The halogens
When a metal reacts with a halogen to form salts, what are they called?
Metal halides
How do you calculate the number of moles in a given mass?
Mass in g divided by the Mr of the element
What is the Relative Atomic Mass?
The average mass of an atom of the element compared to the mass of 1/12th of an atom of Carbon-12
What is a Titration?
They allow you to find out exactly how much acid is needed to neutralise a quantity of alkali (or vice versa).
What is meant by equilibrium?
When the forward reaction goes at exactly the same rate as the backwards reaction.
A + B ⇌ C + D
What does it mean if equilibrium lies to the right?
If equilibrium lies to the right, this means that the concentration of the products is higher than the reactants.
What 3 things affects the positioning of equilibrium?
Temperature, Pressure and Concentration
What is the Contact Process used for?
To make Sulfuric Acid
What is an example of a strong acid and how is it different from a weak acid?
Hydrochloric/Nitric/Sulfuric. Strong acids ionise completely in water and lots of H* ions are released.
What are Spectator Ions?
They don’t change during the reaction. They were in the reactants and still appeared in the products
What do Precipitation reactions involve?
Two solutions reacting to make an insoluble substance
What is the word equation for rust?
iron + oxygen + water → hydrated iron (III) oxide
What methods can you use to prevent rusting?
Painting, Oiling, Greasing, Tin plating, Galvanishing
What is meant by Electrolysis?
The breaking down of a substance using electricity
What are Cations and what are they attracted to?
They are positively charged ions and are attracted to the Cathode (negative electrode)
In the formula to work out the amount of product formed during electrolysis, what do the letters stand for (Q = I x t)
Q = amount of charge (coulombs), I = Current (amps), t = time (seconds)
What is a fuel cell?
An electrical that’s supplied with a fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiently
What are the advantages of Hydrogen-Oxygen Fuel Cells?
- More efficient than power stations
- It has a direct energy transfer, so no turbines or generators etc
- No moving parts, so energy isn’t lost through friction
- No pollution as the only product is water
What are the disadvantages of Hydrogen-Oxygen Fuel Cells?
- Producing the hydrogen needs lots energy
- The energy may have come from fossil fuels, which creates pollution
- Disposing of the poisonous catalysts takes a lot of time and money and may cause environmental problems
What is meant by a Free Radical?
When a covalent bond evenly breaks, resulting in each atom getting one of the shared electrons, e.g H-H → H• + H•. This makes it very reactive.
What is hard water?
When scum (limescale) is formed instead of a lather with soap
What two ions does hard water contain?
Calcium ions (Ca2+) and magnesium ions (Mg2+)
How can you remove temporary hardness?
By boiling it
What is the word equation for temporary hardness?
Carbon dioxide + Water + Calcium Carbonate > Calcium Hydrogencarbonate
What three methods are used to filter water?
Filtration, Sedimentation and Chlorination
What is Chlorination?
Chlorine gas, injected into the water, kills microbes.
What is Sedimentation?
A chemical is added which causes tiny solid particles (which would pass through a filter) to clump together into larger particles. These can then be allowed to settle out or may be filtered.
What is Filtration?
The water is sprayed onto specially prepared layers of sand and gravel. As it trickles through, different sized insoluble solids are removed.
