Atomic Structure + Periodic Table

Question 1

Arrangement of periodic table

Answer 1

• 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

Question 2

Relative atomic mass

Answer 2

protons +neutrons, bigger number

Question 3

Atomic number

Answer 3

number of protons, smaller number

Question 4

John Newlands ( early periodic table )

Answer 4

• ordered his table in order of atomic weight
• realised similar properties occurred every eighth element
  -‘law of octaves’ but broke down after calcium

Question 5

Dmitri Mendeleev (early periodic table)

Answer 5

-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

Question 6

Why was order based on atomic weights not always correct?

Answer 6

Knowledge of isotopes

Question 7

Reactivity of group 1 (alkali metals)

Answer 7

• 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

Question 8

Reactivity of Group 0 (noble gases)

Answer 8

-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

Question 9

Reactivity of group 7 (halogens)

Answer 9

-non-metals
-exist as molecules (Cl2)
-react with metals to form ionic compounds
-react with non metals to form covalent compounds

Question 10

How did John Dalton think atoms were formed

Answer 10

-solid spheres
-different spheres made up different elements

Question 11

What did J J Thompson think about the atom

Answer 11

-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

Question 12

Who created idea of plum pudding model

Answer 12

J J Thompson

Question 13

Who did alpha particle scattering experiment

Answer 13

Ernest Rutherford

Question 14

What was expected to happen in alpha particle scattering experiment

Answer 14

-expected particles to pass straight through because the positive charge of the atom was believed to be very spread out

Question 15

What actually happened in alpha particle experiment

Answer 15

-most particles went straight through the gold sheet
-more were deflected than expected and some were deflected backwards

Question 16

Who came up with idea of nuclear model

Answer 16

Rutherford first, then Bohr

Question 17

What is Rutherford’s nuclear model

Answer 17

-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

Question 18

What is Niels Bohr’s nuclear model

Answer 18

-electrons were contained in shells
-electrons orbit the nucleus in fixed shells and at a fixed distance

Question 19

Who discovered protons and what happened

Answer 19

-Rutherford
-experiments showed that the nucleus could be divided into smaller particles
-same charge as hydrogen nucleus, called protons

Question 20

What did James Chadwick discover

Answer 20

-carried out experiment which provided evidence for neutral particles in nucleus
-now called neutrons

Question 21

Who discovered neutrons

Answer 21

James Chadwick

Question 22

Properties of metals

Answer 22

-all have metallic bonding
-strong
-malleable (can be bent or hammered)
-conduct heat+electricity
-high melting+boiling points

Question 23

Properties of non-metals

Answer 23

-dull looking
-more brittle
-aren’t always solid at room temp
-don’t usually conduct electricity
-lower density

Question 24

Reaction of group 1 elements with water

Answer 24

-produces hydrogen gas
-react vigorously
-the lower down in the group, the more vigorous

Question 25

Reaction or group 1 with chlorine

Answer 25

-react vigorously to form white salts called metal chlorides

Question 26

Reaction of group 1 with oxygen

Answer 26

-react to form a metal oxide

Question 27

Radius of atoms

Answer 27

0.1 nanometers

Question 28

What is atomic number

Answer 28

-smaller number
-tells us how many protons there are

Question 29

What is mass number

Answer 29

-bigger number
-tells us total number of protons and neutrons in atom

Question 30

Relative mass and charge of proton

Answer 30

Relative mass: 1
Charge: +1

Question 31

Relative mass and charge of neutron

Answer 31

Relative mass: 1
Charge: 0

Question 32

Relative mass and charge of electron

Answer 32

Relative mass: very small
Charge: -1

Question 33

Why are atoms neutral

Answer 33

Have same number of protons and electrons

Question 34

What is an isotope

Answer 34

-different forms of the same element
-same number of protons but different number of neutrons
-so same atomic number but different mass number

Question 35

Formula for relative atomic mass

Answer 35

RAM= sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes

Question 36

Chromatography experiment

Answer 36

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

Question 37

Rf value in chromatography formula

Answer 37

Rf= distance travelled by substance/ distance travelled by solvent

Question 38

When is filtration used

Answer 38

-separates insoluble solids from liquids
-can be used for purification as well

Question 39

Evaporation experiment

Answer 39

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

Question 40

Crystallisation experiment

Answer 40

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

Question 41

Simple distillation method

Answer 41

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

Question 42

Problems with simple distillation

Answer 42

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

Question 43

Fractional distillation experiment

Answer 43

(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