Atomic Structure And The Periodic Table Flashcards
Separation techniques
Filtration - insoluble solids from liquids
Separating soluble solids from solutions
Evaporation
1) pour the solution into evaporating dish
2)slowly heat the solution.
3) keep heating until all you are left with is dry crystals
Crystallisation
1) pour solution into evaporating dish and gently heat
2) once some of the solvent has evaporated or crystals begin to form remove from heat and leave to cool
3) the salt will start to form crystals as it becomes insoluble in the cold , high concentrated solution
4) finger the crystals out of the solution and legs ethane in a warm place to dry
History of the atom
Plum pudding - atom as a ball of positive charge with electrons stuck in it
Rutherford proved it wrong with alpha scattering. Nuclear model tiny , positive charged nucleus at the centre with a cloud of electrons surrounding. Most of the atom was empty space.
Bohrs nuclear model
Electrons fixed in shells in orbit
Chadwick found neutral particles which made his model close the modern day nuclear model
Development of periodic table
1800s arranged by atomic weight
Mendel arranged 50 known elements and left gaps. Mainly in order of atomic weight. Gaps were left in the table to ensure elements of similar properties stayed in the same groups.
Today it’s arranged in their physical and chemical properties and atomic weight
Group 1 elements
Reactive , soft metals
As you go down the group
- increase reactivity
- lower melting and boiling points
- higher relative atomic mass
Group 0 elements
Inert , colourless gases
The noble gases
As you go down the group
- boiling points increase as there are more electrons so greater intermolecular forces
Group 7 elements
Halogens are all non - metals with coloured vapours
As you go down the group
- less reactive
- higher melting and boiling points
- high relative atomic masses
More reactive halogens will displace less reactive halogens
Distillation
Simple distillation Separates out solutions
1) separates a liquid from a solution
2) solution is heated. The part with the lowest boiling point evaporates first.
3) vapour is then cooled , condenses and is collected
4) rest is left behind in the flask
Fractional distillation
Separates a mixture of liquids
1) put your mixture in a flask and tick a fractionating column on top
2) the different liquids will have different boiling points and will evaporate at different temperatures
3) the liquid with the lowest boiling point evaporates first. When the temperature on the thermometer matches the boiling pints might also of this liquid it will reach the top of the column
4) the liquids with higher boiling pints might also start to evaporate. But the column is cooler towards the top. They will only get part of the wha up before condensing and moving back to the flask.
6) went he first liquid is collected you raise the temp until the next one reaches the top.
