C5 - Chemicals in the Natural Environment Flashcards
What are the three most abundant elements in the world?
Oxygen, silicon and aluminium
Covalent bonds
Bonds with shared elections
Electrostatic attraction
When the positively charged nuclei are attracted to the negatively charged shared pair of electrons
Why do simple molecular structures have low melting points?
Because they have weak intermolecular bonds
What is the hydrosphere?
All of the water on Earth e.g. Oceans, seas, lakes and rivers
What structure do ionic compounds form?
A crystal lattice
Why do ionic compounds have high melting points?
Because they have very strong intermolecular forces and the ions have strong attractive forces
Why do ionic compounds only conduct electricity when molten?
When molten or dissolved, ionic compound conduct electricity because the ions are free to move
What colour precipitate does a Calcium ion form? And is it soluble?
White: insoluble in excess
What colour precipitate does a Copper ion form? And is it soluble?
Light blue: insoluble in excess
What colour precipitate does an Iron (II) ion form? And is it soluble?
Green: insoluble in excess
What colour precipitate does an Iron (III) ion form? And is it soluble?
Red-brown: insoluble in excess
What colour precipitate does a Zinc ion form? And is it soluble?
White: soluble in excess
How do you test for a Carbonate ion? (2)
Add dilute acid and see if Bubbles (effervescence) occurs
How do you test for a Sulphate ion? (4)
Add dilute acid then acidity with nitric acid then add barium chloride/ nitrate; see if a white precipitate forms
How do you test for a Chloride ion? (4)
Add dilute acid then acidity with nitric acid then add silver nitrate; see if a white precipitate forms
How do you test for an Iodide ion? (4)
Add dilute acid then acidity with nitric acid then add silver nitrate; see if a yellow precipitate forms
How do you test for a Bromide ion?(4)
Add dilute acid then acidity with nitric acid then add silver nitrate; see if a cream precipitate forms
What is the Lithosphere?
The rigid outer layer of the Earth, made up of the crust and upper mantle
Ore
A rock containing a metal/ metal compound
Name as many properties of metals as you can: (7)
Malleable, solid, strong/ hard, shiny, high melting/ boiling points, good conductor, free electrons to carry electrical current
Alloy
A mixture of different metals
What element is used to extract iron, zinc and copper?
Carbon
What is a redox reaction?
A reaction where oxidation and reduction take place
What is another name for aluminium ore?
Bauxite
Give the four properties of aluminium?
Lightweight, flexible, strong and durable
What are the conditions needed for aluminium electrolysis? (3)
955 degrees Celsius, 4.5V and 157,000 Amps
Name as many properties of diamond as you can: (7)
- Expensive and rare
- Giant covalent structure
- Transparent
- Used in drill tips & jewellery
- Carbon atoms bonded to four others in tetrahedral pattern
- Doesn’t conduct electricity
- Hard and strong
Name as many properties of graphite as you can: (7)
- Cheap and common
- Has delocalised electrons between the layers
- Black
- Used in pencil lead and as an electrode during electrolysis
- Soft with weak bonds between layers
- Conducts electricity
- Carbon atoms bonded to three others in sheets
Name as many properties of silica/ silicon dioxide as you can: (6)
- makes up most of the Earth’s crust
- Silicon atoms bonded to four oxygen atoms
- Hard & strong
- High melting and boiling points
- Insoluble
- Doesn’t conduct electricity
What is the equation to calculate the % of metal in a mineral?
% metal + total mass of metal atoms / gram formula mass X 100
Electrolysis
Passing an electric current through an ionic compound when it is molten/ dissolved in water
Why is Aluminium extracted using electrolysis?
It is very reactive so it’s oxide cannot be reduced by carbon
Why do metals form at the cathode and non metals at the anode?
Metals form positive ions and non metals form negative ones
Why are metals malleable?
All the atoms are the same size and care roll over each other while keeping the bonds
Give three examples of poisonous metals
Lead, mercury and cadmium
Why is sulphur dioxide harmful to the environment?
It helps form acid rain which damages plants and fish
What is lithium used for?
Batteries
Why don’t we use lead to make batteries anymore?
Lead is toxic
What do we use copper for?
Electrical wiring, pipes and building materials
What substances are in dry air in what percentages?
Nitrogen - 78%
Oxygen - 21%
Carbon Dioxide - 0.04%
Argon & other gases -
