Studied by 7 people
How small are atoms?
1 × 10¹⁰
How small is the nucleus of the atom?
1 ×10¹⁴
What is the relative atomic mass of the proton, neutron and electron?
Proton- 1
Neutron- 1
Electron- very small
What is the mass number of an atom?
The sum of protons and neutrons
What is the atomic number of an element?
Number of protons, which is the same as the number of electrons
What are isotopes?
Atoms of the same element with a different number of neutrons
How to calculate relative atomic mass?
Sum of (isotope abundance x isotope mass number) ÷ sum of abundances of all the isotopes
What is relative atomic mass?
The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element
What is an atom?
The smallest part of an element that can exsist
What is a mixture?
Two or more elements or compounds that are not chemically joined together
How to use filtration to separate an insoluble solid from a liquid?
Fold filter paper into a cone shape, place it in your container and pour the liquid into it. The solid will be left on the filter paper
How to use evaporation to separate soluble solids from solutions?
Pour the solution into an evaporating dish.
Heat the solution, the solvent will evaporate and the solution will get more concentrated then crystals will start to form.
Keep heating the solution until you only have the dry crystals.
How to use crystallisation to separate soluble solids from solutions?
Pour the solution into an evaporation dish and heat the solution
once some of the solvent has evaporated or crystals start to form remove the dish from the heat
Crystals should start to form as it becomes insoluble in the cold
Filter the solution and pat the crystals dry.
How to use filtration to separate rock salt?
Grind the mixture so the salt crystals are small and can dissolve easily.
Put the mixture in water and stir, the salt will dissolve but the sand won’t.
Filter the mixture, the salt will pass through the sand won’t.
Evaporate the water fromthe salt so it forms crystals.
How to use distillation to separate out solutions?
Heat the solution, the part of the solution with the lowest boiling point evaporates first.
The vapour will cool in the condensation tube.
The rest of the solution is left in the flask.
How to use fractional distillation to separate out a mixture of liquids?
Put your mixture in a flask with a fractioning column at the top.
The liquid with the lowest boiling point evaporates first and reaches the top of the column.
Liquids with higher boiling points may also start to evaporate but the column is cooler towards the top so they will condense back down.
Continue raising the temperature for each liquid.
How to do paper chromatography?
Draw a line near the bottom of a sheet of filter paper, add a spot of ink to the line and place the paper in a beaker of shallow solvent so the ink is not touching it.
Put a lid on the container to stop it evaporating.
The solvent seeps up the paper carrying ink with it, each dye will move up the paper at a different rate so the dyes will separate out.
When the solvent has nearly reached the top of the paper take your chromatograph out the and leave it to dry.
What did John dalton describe the atom as?
Solid spheres
What did JJ Thompson discover and what did he describe the atom as?
Electrons
The plum pudding model- ball of positive charge with electrons embedded in it
What did Earnest Rutherford discover about the atom with the alpha scattering experiment?
They fired alpha particles at a thin sheet of gold some passed through some deflected and some bounced backwards.
There is a small positively charged nucleus at the centre of the atom
This is surrounded by a cloud of negative electrons
The atom is mostly empty space
What did Niels Bhor discover about the atom?
Electrons orbit the nucleus in shells at fixed distances (otherwise the atom would collapse)
Did the discovery of the protons or neutrons come first?
Protons
How did the periodic table used to be organised? (1800s)
By atomic weight
Why is the periodic table called the periodic table?
The similar properties in groups occur at regular intervals
What was wrong with organising the table by atomic weight?
The groups in the table where incomplete and some elements where in the wrong groups due to the existence of isotopes.
Why did Dmitri Medeleev leave gaps in his periodic table?
He left them as he organised the table so that elects with similar properties stayed in the same groups, the gaps allowed him to predict what properties the element has. Once they were discovered they fit the pattern.
Why do elements in the same group have similar properties and react similarly?
They have the same number of electrons on their outer shell and this gives them similar chemical properties
What are metals?
Elements that react to form positive ions
What are the physical properties of metals?
strong but malleable
Good conductors of heat and electricity
High boiling and melting points
What are the physical properties of non-metals?
Dull
Brittle
Don’t conduct electricity
Aren’t always solids
Why are non-metals near the top right of period table?
Non-metals are near the right because they have lots of electrons on their outer shell
They are near the top because their outer shell electrons are closer to the nucleus (less shells)
Why are metals towards the bottom left of the periodic table?
To the left- not many electrons to remove
To the bottom- outer electrons which are long way from the nucleus (weaker force of attraction
What are the properties of transition metals?
Shiny, strong, good conductors
Form more than one type of ion
Coloured
What are the trends of group 1 metals? + one property
Soft
Increasing reactivity down the group
Lower melting/boiling points
Higher relative atomic mass
What do group one elements produce when reacted with water?
Metal hydroxides + Hydrogen
What do group one elements produce when reacted with chlorine?
Metal chloride salts
What do group one elements produce when reacted with oxygen?
Metal oxides
Compare group 1 metals to transition metals.
Group 1 is more reactive
Group 1 is less dense, strong and hard
Group 1 has lower boiling/melting points
What are properties of group 7 elements?
They are colourful
Exist as molecules
What are the trends in group 7 elements?
Less reactive as you go down the group
Higher melting and boiling points as you go down the group
Higher relative atomic masses as you go down the group
What happens if a more reactive halogen reacts with a less reactive one?
The less reactive one is displaced by the more reactive one
What are the properties of group 0 elements?
inert
Colourless
Exist as monatomic gases
What is a trend in the Nobel gases and why?
Boiling points increase as you go down the group, the increase in boiling point is due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome.
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