Chemistry - C1 - C3 Flashcards
What are the 3 states of matter?
Solid, Liquid and Gas
Who made the Plum Pudding Model of the atom, and what was it?
J.J Thomson - negatively charged particles (electrons) sat in a positively charged “pudding”
What did Bohr’s Model tell us?
Bohr suggested that electrons can only exist in fixed orbits, or shells.
What was Rutherfords Experiment?
Gold Leaf experiment
What did Bohr’s Model tell us?
That electrons can only exist in fixed orbits, or shells, and not anywhere in-between. We also know that there is a positively charged nucleus
What is the relative mass of an electron?
5x10^-4 OR 0.0005
What are the properties of metals? (part 1)
1) In metals, the outer electrons of each atom can move freely, making the atoms become positive ions with a “sea” of delocalised electrons around them. This allows them to conduct electricity
2) Metallic bonding is the electrostatic attraction between these ions and electrons. The ions are surrounded by the electrons, so the attraction acts in all directions.
What are the properties of metals? (part 2)
1) High melting/boiling point and high density
2) They’re strong but malleable
3) Good conductors of electricity and heat
4) Reacts with oxygen to form metal oxides
5) Mixed with other elements to make alloys
Are the melting points low or high for:
1) Simple Covalent Bonding
2) Metallic Bonding
3) Ionic Bonding
4) Giant Covalent Structures
1) Low
2) High
3) High
4) High
What are the 5 methods of separation?
Simple Distillation Fractional Distillation Filtration Crystallisation Chromatography
Why is Simple Distillation used, and how does it work?
Simple Distillation is used to separate out a liquid from a solution.
The liquid is evaporated out of the solution and is left in another beaker
The solute is left in the original beaker
Why is Fractional Distillation used, and how does it work?
Fractional Distillation is used to separate a mixture of liquids.
The mixture is put into a flask, where it is gradually heated. The liquid with the lowest boiling point evaporates first, condensing into another beaker (like how it was done in simple distillation) and the rest evaporate as it gets hotter
Why is Filtration used, and how does it work?
Filtration is used to separate an insoluble solid from a liquid, such as sand.
This is simply just filtering out the solid with filter paper
Why is Crystallisation used, and how does it work?
Crystallisation separates a soluble solid from a solution.
Gently heat the solution so that the the solvent can start to evaporate, increasing the concentration of the solution. Once some of the solution has evaporated, remove the crystals from the heat and let it cool down. The salt should start to form crystals which you can then filter out.
Balance this equation:
Mg + O2 —> MgO
2Mg + O2 —-> 2MgO
What is Avagadros Constant?
6.022x10^23
How do you work out the number of moles?
Moles = Mass in g / Formula Mass n = m / Mr
Example:
How many moles are there in 66g of carbon dioxide?
Mr of Carbon Dioxide = 12.0 + (16.0 x 2) = 44.0
Moles = mass / Mr = 66 / 44.0 = 1.5 moles
Example:
Calculate the mass of aluminium oxide formed when 135g of Aluminium is burned in air
4Al + 3O₂ —> 2Al₂ + Al₂O₃
1) Write out the balanced equation (Given)
2) Calculate the relative atomic or formula masses of the reactants and products you’re interested in
Al: 27 Al₂O₃: (27.0 x 2) + (16.0 x 3) = 102.0
3) Calculate the number of moles of aluminium in 135g
moles = mass / Mr = 135/27 = 5
4) Look at the ratio of moles in the equation
4 moles of Al react to produce 2 moles of Al₂O₃ -
ratio of 2:1, so 2.5 moles of Al₂O₃
5) Calculate the mass of 2.5 moles of Al₂O₃
mass = moles x Mr = 2.5 * 102.0 = 255g
What is an exothermic reaction?
An exothermic reaction is one which gives out energy to the surrounds, usually in the form of heat and usually show by a rise in temperature of the surroundings
What is an Endothermic Reaction?
An Endothermic Reaction is one which takes in energy from the surrounds, usually in the form of heat and usually shown by a fall in temperature of the surroundings.
What is Activation Energy?
Activation energy is the energy needed to start a reaction (difference between highest point on curve and reactants)
Bond Energy Calculations:
Overall Energy Charge = Energy required to break bonds - energy released by forming bonds
What are Acids and Bases?
An acid is a substance with a pH less than 7. Acids form H+ ions in water
A base is a substance with a pH greater than 7
- An Alkali is a base that dissolves in water. Alkalis form
OH- ions in water
