1 Atomic structure and the periodic table Flashcards
1
Q
how to do paper chromotography
A
- Use a ruler to draw a horizontal pencil line 2 cm from the bottom short edge of the chromatography paper- origin line
- add a spot of ink to the line and place the sheet in a beaker of solvent eg. water
- add the piece of paper into the water with only the bottom submerdeged eg. 1cm
- clip the top to a wooden spill resting on the top of the beaker
- put a lid on top to stop the solvent evaporating
- the solvent seeps up the paper carrying the ink with it
- each dye in the ink will move up the paper at different rate forming a spot
- if any ink is insoluable it will stay on the baseline
- when the solvent has nearly reached the top of the paper take it out and dry it
- the end result is a chromotogram
2
Q
how to seperate insoluble solids from liquids
A
- filytration
- filter ppaer folded into a cone shape - solide is let in the filter paper
3
Q
how to seperate soluble solids from solution
A
- evaporation
- crystallisation
4
Q
how to seperate a soluble solid from a solution using evaporation
A
- pour solution into evaporation dish
- slowly heat the solution
- solvent will evaporate
- solution gets more concentrated
- crystals form
- heat until all left is dry crystals
5
Q
how to seperate a soluble solid from a solution using crystallisation
A
- pour solution into evporating dish
- gently heat
- some solvent will evaporate and solution gets more concentrated
- once some solvent evaporated or when crystals start to form, remove dish from hea and leave to cool
- salt shoudl form crystals as it becomes insoluble in the cold, highly concentrated solution
- filter the crystals out of solution
- leave them in warm place to dry
- use a dryign oven or desiccator
6
Q
how to do distillation
A
- solution is heated, part of solution that has lowest boiling point evaporates first
- vapur is colled, condensed and collected
- in the tube carrying the condensed water a condensor goes around it - water goes in from the bottm and water out from the top
- cna be used to seperate solutions of very dfferent boiling temps
7
Q
explain the alpha particle experiment and what it achieved
A
- fired positive alpha particles at a thin sheet of gold
- from plum pudding model, expecting for paeticles to pass straigth throigh or besligthly deflected at most - believed postive charge of each atom was thougth to be veyr spread out
- while most particles did go straight through some delfexted mro ethan expected and backwards - plum pudding model can’t be right
- led to discovery of nucleus at the centre, where nost mass is concentrated, a ‘cloud’ of negative charge sourrounds, so most of the psace is empty
- when the alpha particles cam enear the nucleus they were dlefected - positive and positive
8
Q
order of models of the atom
A
- 19th centruy, John Dalton, described atoms as solid spheres
- 1897 JJ Thompson, discovered existence of electrons, plum pudding model, ball of positive chare with negative elctrons embeded in it
- 1909 Ernest Rutherfod nuclear model, most of the atom empty space, nucleus in the centre with concentrated mass, positive, ‘cloud’ of electrons surrounded the nucleus
- Bohr , proposed electrons orbit in shells around the nucleus
- James Chadwick dicovered neutrons
9
Q
how did Mendeleev order elements in the periodic table
A
- order of atomic mass
- wouls swich order if porperties meant it should be changes
- previously it was ordered by relatiev atomic mass
10
Q
why did mendeleev switch Te and I
A
- Iodine has smaller relative atomic mass but placed after terilium as it has similiar properties as group 7
11
Q
why did Mendeleev leave gaps in his periodic table
A
- to make sure elements wiht similiar properties staued in the same groups
- the se gaos indicated existence of undisovered elements, allowed Mendeleev to predict their properties
- made really good predictions on ekasilicon - germanium
- discovery of isotopes proves mendeleev was right to only pace by atomic mass
12
Q
properties of metals
A
- form posite ions when react
- strong, are malleable
- good conductors of heat and electricty
- have high melting and boiling point
13
Q
**
properties of non metals
A
- brittle
- aren’t always solids at room temperature
- don’t generally conduct electricty
- have lowe density
14
Q
properties of transition metals
A
- same as metals
- cna have mroe than one ion eg. Cu+ Cu2+
- often coloured, so compunds containing theses tned to be colourful
- make good catalysts
15
Q
group 1 elements properties
A
- one electron in outer shell so very reactive
- soft
- low density
