C1 Flashcards
History of the atom(6 marker)
Dalton- atoms are tiny hard spheres that cannot be broken down
Jj thomson- discovered electrons with cathode rays- made plum pudding model- positive charged ball with negatively charged electrons stuck inside.
Geiger and Marsden- gold foil alpha particle experiment.
Rutherford proposed these conclusions from Geiger and Marsden’s experiment:
Some bounced back- mass of atom concentrated in centre
Some deflected- centre of atom is positive
Most passed straight through- atom is mainly empty space
Bohr- proposed shells and every atom has a specific number of shells and said electrons must be at fixed distances from nucleus due to light given out when heated at specific amounts of energy so must be when electrons fall from high to low energy level they release light. Proposed nuclear model of the atom.
Chadwick- discovered neutrons with experiment(very difficult as they have no charge)
Charge of a proton
+1
Charge of an electron
-1
Charge of a neutron
0
Relative mass of protons and neutrons and electrons
1
1
Very small(0.0000001)
Elements
Contain only one type of atom
Atoms
The smallest part of an element
Compound
2 or more different elements chemically bonded together
Molecule
2 or more atoms
Mixture
Can be made of elements, compounds, molecules and atoms not chemically bonded just mixed together
Atoms cannot be
Created or destroyed
Aqueous
Dissolved in water
Is mass number the top or bottom number on periodic table
Top
Is atomic number the top or bottom number of periodic table
Bottom
Mass number
Number of protons and neutrons
Atomic number
Number of protons/electrons
Ion
Atom with a charge
Isotopes
Atoms of the same element with a different number of neutrons but same number of protons
Electronic structure
2,8,8 etc
Outer shell is full
Atom is stable
Paper chromatography
Draw a line near the bottom of filter paper. Also draw one near the top in pencil as it’s insoluble.
Put dots of the inks you are using on the lines.
Fill a beaker with water- make sure it’s shallow.
Put the filter paper in and carefully dip into into the water.
Put a lid on beaker to make sure no solvent evaporates
Make sure the line does not go in the water so the inks don’t dissolve
The solvent seeps up the paper, carrying the ink with it.
Leave until the dyes of the ink get close to the top line and then take it out and leave to dry
You now have a pattern of spots called a chromatogram.
The ink will separate into its dyes as each dye will move up the paper at different rates as it dissolves at different rates.
Further up= more soluble
Each dye will form a dot in a different place.
Relative atomic mass equation
Sum of(isotope abundance X isotope mass number) divided by sum of abundances of all the isotopes.
Filtration
If one thing is soluble in water and other is insoluble, add water to dissolve soluble thing then filter to separate them
Evaporation
Use to get salt when salt doesn’t decompose when heated
Use crystallisation
If it does break down when heated
Filtration and crystallisation can be used together
To separate and form crystals
Use simple distillation when:
Substances have very different boiling points
If BP’s similar use:
Fractional distillation
Simple distillation method
Put solution of compound with 2 substances with different BP’s
Heat
One with lowest BP will boil first and evaporate out
Will go through the condensing chamber, condensing it to a liquid
They are now separated
One in first conical flask, one in the other
Fractional distillation method
Put mixture of compounds in conical flask with seal on it and thermometer
Heat
Add fractionating column to distillation apparatus.
Fractionating column is hot at bottom and cool at top
One with lowest bp will evaporate first and rise up through the fractionating column
Stop heating when first starts to evaporate
Others will rise up but then cool as it goes up the fractionating column, condensing so it goes back down into the conical flask
Lowest bp will go through condensing chamber and be collected in conical flask.
Heat when all lowest bp collected to next lowest compounds bp
Will do the same
Keep going for each one and collect in different flasks to separate them
