Atomic Structure + Periodic Table Flashcards
1
Q
Arrangement of periodic table
A
- elements arranged in order of atomic number and so elements of similar properties are in columns (groups)
- elements in the same group have the same amount of electrons in their outer shell-gives them similar chemical properties
2
Q
Relative atomic mass
A
protons +neutrons, bigger number
3
Q
Atomic number
A
number of protons, smaller number
4
Q
John Newlands ( early periodic table )
A
- ordered his table in order of atomic weight
- realised similar properties occurred every eighth element
- ‘law of octaves’ but broke down after calcium
5
Q
Dmitri Mendeleev (early periodic table)
A
- ordered his table in order of atomic mass, but not always strictly (in some places he changed order based on atomic weights)
- left gaps for elements that he thought had not been discovered
6
Q
Why was order based on atomic weights not always correct?
A
Knowledge of isotopes
7
Q
Reactivity of group 1 (alkali metals)
A
- all react with oxygen to create an oxide
- all react with chlorine to form a white precipitate
- reactivity of elements increases going DOWN the group
- react vigorously with water to create an alkaline solution and hydrogen
8
Q
Reactivity of Group 0 (noble gases)
A
- full outer shells
- unreactive and don’t easily form molecules because they have a stable arrangement of electrons
- boiling points of noble gases increase going down the group
9
Q
Reactivity of group 7 (halogens)
A
- non-metals
- exist as molecules (Cl2)
- react with metals to form ionic compounds
- react with non metals to form covalent compounds
10
Q
How did John Dalton think atoms were formed
A
- solid spheres
- different spheres made up different elements
11
Q
What did J J Thompson think about the atom
A
- concluded atoms weren’t solid spheres
- believed atoms must contain negatively charged particles:electrons
- this theory was the plum pudding model
- was shown as a ball of positive charged particles with electrons stuck in it
12
Q
Who created idea of plum pudding model
A
J J Thompson
13
Q
Who did alpha particle scattering experiment
A
Ernest Rutherford
14
Q
What was expected to happen in alpha particle scattering experiment
A
- expected particles to pass straight through because the positive charge of the atom was believed to be very spread out
15
Q
What actually happened in alpha particle experiment
A
- most particles went straight through the gold sheet
- more were deflected than expected and some were deflected backwards
16
Q
Who came up with idea of nuclear model
A
Rutherford first, then Bohr
17
Q
What is Rutherford’s nuclear model
A
- tiny positively charged nucleus as centre where most of the mass is concentrated
- a ‘cloud’ of negative electrons surround nucleus
- so most of the atom is empty space
18
Q
What is Niels Bohr’s nuclear model
A
- electrons were contained in shells
- electrons orbit the nucleus in fixed shells and at a fixed distance
19
Q
Who discovered protons and what happened
A
- Rutherford
- experiments showed that the nucleus could be divided into smaller particles
- same charge as hydrogen nucleus, called protons
20
Q
What did James Chadwick discover
A
- carried out experiment which provided evidence for neutral particles in nucleus
- now called neutrons
21
Q
Who discovered neutrons
A
James Chadwick
22
Q
Properties of metals
A
- all have metallic bonding
- strong
- malleable (can be bent or hammered)
- conduct heat+electricity
- high melting+boiling points
23
Q
Properties of non-metals
A
- dull looking
- more brittle
- aren’t always solid at room temp
- don’t usually conduct electricity
- lower density
24
Q
Reaction of group 1 elements with water
A
- produces hydrogen gas
- react vigorously
- the lower down in the group, the more vigorous
25
Reaction or group 1 with chlorine
- react vigorously to form white salts called metal chlorides
26
Reaction of group 1 with oxygen
- react to form a metal oxide
27
Radius of atoms
0.1 nanometers
28
What is atomic number
- smaller number
- tells us how many protons there are
29
What is mass number
- bigger number
- tells us total number of protons and neutrons in atom
30
Relative mass and charge of proton
Relative mass: 1
Charge: +1
31
Relative mass and charge of neutron
Relative mass: 1
Charge: 0
32
Relative mass and charge of electron
Relative mass: very small
Charge: -1
33
Why are atoms neutral
Have same number of protons and electrons
34
What is an isotope
- different forms of the same element
- same number of protons but different number of neutrons
- so same atomic number but different mass number
35
Formula for relative atomic mass
RAM= sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes
36
Chromatography experiment
1. Draw a line near bottom of sheet of filter paper (use pencil, insoluble)
2. Add spot of ink to the line and place the sheet in a beaker of solvent eg. Water
3. Make sure ink isn’t touching solvent, so it doesn’t dissolve in it
4. Place a lid on top of container so solvent doesn’t evaporate
5. Solvent seeps up paper, carrying ink with it
6. Each component in the ink will move up paper at different rate so the dyes will separate out and form a spot in a different place
7. If any components are insoluble in the solvent used, they will stay on the baseline
8. When the solvent has nearly reached the top of the paper, take the paper out to dry
37
Rf value in chromatography formula
Rf= distance travelled by substance/ distance travelled by solvent
38
When is filtration used
- separates insoluble solids from liquids
- can be used for purification as well
39
Evaporation experiment
1. Pour solution into evaporating dish
2. Slowly heat solution. The solvent will evaporate and the solution will get more concentrated
3. Eventually crystals will form
4. Keep heating until all is left is dry crystals
40
Crystallisation experiment
1. Perform evaporation
2. Once crystals start to form, remove evaporating dish from heat and leave to cool
3. Filter crystals out of highly concentrated solution
4. Leave in a warm place to dry
41
Simple distillation method
1. Solution is heated, part if solution that has the lowest boiling point evaporates first
2. The vapour is cooled and condenses and is collected
3. The rest of the solution is left behind in the flask
42
Problems with simple distillation
You can only use it to separate things with very different boiling points, if the temperature goes higher than the highest boiling the point, they will mix again
43
Fractional distillation experiment
(Usually separates crude oil)
1. Our mixture in a flask and stick a fractionating column on top, then heat it
2. Different liquids have different boiling points, they’ll evaporate at different temperatures
3. Liquid with lowest boiling point evaporates first when thermometer matches boiling point of liquid, it will reach top of column and collect
4. Other liquids with higher boiling points might start evaporating but they won’t make it to the top of the column as it’s cooler at the top so they’ll condense back down
5. Once first liquid is collected, raise the temperature and move onto next liquid and so on
