Chemistry in Society Flashcards
State the definition of a metallic bond
Metallic bond is the electrostatic force of attraction between positively charged ions and delocalised electrons.
Explain the properties of metallic bonding
Metallic elements can conduct electricity (in any state).
This is because they have delocalised electrons (delocalised electrons are free to move).
Write equations for the reactions of metals with oxygen, water and acid
Metal + oxygen → metal oxide
Metal + water → metal hydroxide + hydrogen
Metal + dilute acid → salt + hydrogen
State what happens when a metal is extracted
The higher up a metal is on the electrochemical series, the harder it is to extract the metal from its ore.
During extraction the metal ions are reduced to metal atoms.
Describe electrolysis
Electrolysis is a method of extraction using electricity. It involves the decomposition of ionic compounds into its elements.
A d.c (direct current) power supply should be used to help identify the products as the electrodes will have a permanent charge.
The negative ions go to the positive electrode and the positive ions go to the negative electrode (remember opposites attract).
State the definition of the term electrolyte
Electrolyte is a solution that contains ions which can conduct electricity.
State the use of an ion bridge
Ion bridge is used to complete the circuit by linking the two half-cells.
Define a polymer
Polymers are long-chanined molecules which are made by joining monomers together.
Polymers are examples of plastics.
State the definition of addition polymerisation
Addition polymerisation is a chemical reaction that involves making a polymer through an addition reaction.
The polymer is made from unsaturated monomers (contain C=C double bond) join together.
State the definition of a monomer and a repeating unit
A monomer is a small molecule that can be joined together to form a polymer.
The repeating unit is the shortest repeating section of the polymer.
Explain the importance of fertilisers
Fertilisers are used by farmers to restore essential nutrients to the soil.
State the elements found in fertilisers
Nitrogen, Potassium, Phosphorus
State the properties of ammonia and the reactions it can do
Ammonia is a colourless gas with a distinctive smell. It is soluble in water and can react with acids to form an ammonium salt + water.
Ammonia solution + an acid → ammonium salt + water
Write a balanced equation for the Haber Process
H2(g) + 3N2(g) ⇋ 2NH3(g)
Explain the conditions used in the Haber Process
The Haber process uses a moderate temperature (too low a temperature the reaction is very slow, too fast and the backward/reverse reaction is favoured so more reactants will be produced than product).
An Iron catalyst is used.
State the products, reactants and catalyst used in the Ostwald process
Product - Nitric acid
Reactant - Ammonia, oxygen and water
Catalyst - Platinum
You DO NOT need to know the balanced equation for this process.
Describe radioactive decay
Radioactive decay is when unstable nuclei become stable by giving out alpha, beta or gamma radiation.
The radioactive elements tend to be larger atoms.
Describe the properties of an alpha, beta and gamma particles
Alpha particles
Positively charged so is attracted to negative plate.
Can only travel a few cm and are easily stopped by paper.
Beta particles
Electrons given out by nucleus. Have a negative charge so attracted to a positive plate.
Can travel about 1m but can be stopped by a thin sheet of aluminium.
Gamma rays
Electromagnetic waves so are not effected by any charged plates.
They can travel long distances and can be stopped using barriers of lead or concrete.
State the definition of a half-life
Half- life is the time taken for a nuclei of an isotope to half its radioactivity.
State some uses of radioactive isotopes
Medical
Sterilising equipment, in cancer treatments, as a tracer in diagnostics.
Industry
In smoke alarms, to ensure the thickness of paper and to detect leaks.
Exam tip
You DO NOT need to know set examples BUT would need to explain why a particular radioisotope is suitable. For example - in smoke detectors a long half-life so they do not need to be changed and alpha radiation, so it does not travel far.
As a tracer in the body - not a short half-life so it can’t be detected but not long as it would stay in the body.
