Topic 1-Atomic Structure and the Periodic Table

Question 1

What methods are there to separate mixtures?

Answer 1

Filtration
Crystallisation
Simple distillation
Fractional distillation
Chromatography

Question 2

What was the plum pudding model?

Answer 2

The concept that an atom was a ball of positive charge with negative electrons embedded in it

Question 3

What was Rutherford’s alpha particle scattering experiment?

Answer 3

A beam of alpha particles was aimed at very thin gold foil and their passage through was detected

Some of the alpha particles emerged from the foil at different angles and some even came straight back

The positively charged alpha particles were being repelled and deflected by a small concentration of positive charge in the atom (nucleus)

Question 4

What was concluded after the particle scattering experiment?

Answer 4

It was concluded that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged

Question 5

Who suggested that electrons orbited the nucleus at specific distances?

Answer 5

Niels Bohr

Question 6

How did James Chadwick contribute to the atom model?

Answer 6

He provided the evidence to show the existence of neutrons within the nucleus

Question 7

What is the radius an atom?

Answer 7

0.1nm

1x10^-8cm

Question 8

What is the radius of a nucleus?

Answer 8

1x10^-14

Less that 1/10,000 of that of the atom

Question 9

What are isotopes?

Answer 9

They are atoms of the same element with different numbers of neutrons

Question 10

How do you calculate relative atomic mass?

Answer 10

((isotope 1 mass x abundance) + (isotope 2 mass x abundance)) ÷ 100

Question 11

Describe and explain chromatography

Answer 11

Draw line with pencil on filter paper

Add spot of ink then place paper in solvent (not touching to avoid dissolution)

The solvent will slowly rise, separating the spot into few spots.

Question 12

In chromatography, why must you use a pencil to draw the line and not a pen?

Answer 12

Pen ink is soluble and will dissolve in the solvent

Question 13

In chromatography, what is the end result called?

Answer 13

It is called a chromatogram

Question 14

Why must you place a lid on top of the solvent in chromatography

Answer 14

This is to stop the solvent from evaporating

Question 15

Describe and explain simple distilation

Answer 15

The solution is heated and the part of the solution that has the lowest boiling point evaporates first

The vapour is cooled, condenses and is collected

The rest of the solution is left behind in the flask

Question 16

What is the problem with simple distilation?

Answer 16

You can only use it to separate things with very different boiling points

Question 17

Describe and explain fractional distilation

Answer 17

Put your mixture in a flask and put a fractionating column on top. Then heat it

Liquid boiling points evaporate firsts and once the temperature reached the boiling point of this liquid, it will reach the top of the column where it will condense down.

Once the first liquid has evaporated you can raise the temperature until the next one reached the top

Question 18

In fractional distillation, why does it not matter if liquids with higher temperatures also start to evaporate at the same time?

Answer 18

The column in cooler at the top and so it will only reach part of the way before condensing back down

Question 19

Describe and explain filtration

Answer 19

Filter paper is folded into a cone and placed at the top of a beaker

Then, pour your mixture into the cone. The filter paper will catch the insoluble solid (residue) while the filtrate comes through the paper

Question 20

Describe and explain crystallisation

Answer 20

Pour solution into evaporating dish and heat solution. Some solvent will evaporate and the solution will become more concentrated

Once some solvent has evaporated, remove dish from the heat and leave the solution to cool

Salt should start forming crystals as it becomes insoluble in the cold, highly concentrated solution

Filter solution to get crystals out and leave them in a warm place to dry or use a drying oven

Question 21

What is a separating funnel?

Answer 21

An apparatus for separating immiscible liquids.

Two immiscible liquids of different densities will form two distinct layers in the separating funnel

We can run off the bottom layer (greater density) to a separate vessel

Question 22

Who created the periodic table?

Answer 22

Dmitri Mendeleev in 1869

Question 23

How did Mendeleev arrange the periodic table?

Answer 23

He ordered elements in order of increasing atomic mass

Question 24

What was special about Mendeleev’s periodic table?

Answer 24

He had left gaps for undiscovered elements

He showed elements with similar chemical properties lined up in groups

Question 25

Arrangements by atomic mass provided Mendeleev with some elements that didn't fit the patten, such as Argon. Explain how this problem was overcome

Answer 25

Table was arranged by atomic number Discovery of isotopes

Question 26

Alcohols are flammable Suggest how a mixture of alcohols should be safely heated so that they can be separated and collected?

Answer 26

Heat the mixture using a water bath

Question 27

Name some apparatus used during distillation

Answer 27

``` Thermometer Condenser Round-bottom flask Clamp/clamp stand Fractional column ```

Question 28

A student is given a mixture of salt and sand Describe a method the student could use to separate the mixture The student should obtain salt crystals and dry sand

Answer 28

Place mixture in the beaker Add water to the mixture Stir using a stirring rod Filter the mixture by folding a piece of filter paper into a cone and place it into a filter funnel. Pour the mixture in Residue is sand Dry residue in warm oven Evaporate some of the water from filtrate using a Bunsen burner and an evaporating dish Allow solution to cool and form crystals. Remove and dry solution

Question 29

Describe what you would see when sodium is added to water

Answer 29

Fizz/Effervescence Floats Melts Dissolves

Question 30

Explain the trend in reactivity of group 1 metals with water

Answer 30

Outer shell electron is further from nucleus because the atomic radius increases. The force of attraction between the outer electron and the nucleus becomes weaker. Outer shell electron is move easily lost

Question 31

Mendeleev places hydrogen at the top of Group 1 in his version of the periodic table The modern periodic table does not show hydrogen in Group 1 State two similarities between hydrogen and the elements in Group 1

Answer 31

One electron on the outer shell Forms ions with 1+ charge

Question 32

Mendeleev changed the position of iodine in his version of the periodic table so it was in the same group as chlorine Give two reasons why he put iodine in the same group as chlorine?

Answer 32

They have similar properties Iodine is diatomic They have similar reactivity

Question 33

Protons and electrons were discovered after Mendeleev proposed his version of the periodic table Describe how the numbers of protons and electrons in atoms are used to place elements in the modern periodic table

Answer 33

The modern periodic table is arranged by atomic number which is the amount of protons and electrons are in an atom Same groups have the same number of outer electrons

Question 34

What are some properties of alkali metals? (group 1)

Answer 34

Low densities Low melting points Form positive ions with a single positive charge Soft and malleable Conduct electricity Francium does not share these properties. It is highly unstable and breaks down as soon as it is formed

Question 35

What are some properties of noble gases?

Answer 35

Colourless gases Very low melting points Poor conductors Non-flammable Very unreactive

Question 36

Why do noble gases' boiling points increase as you move down the column?

Answer 36

It is because as molecules get bigger, the intermolecular forces between the atoms increase

Question 37

What are some physical properties of halogens?

Answer 37

Low melting and boiling points Poor conductors Toxic Coloured

Question 38

Why do elements become less reactive as you move down the column? (group 7)

Answer 38

The outermost shell being increasingly further away from the nucleus makes it difficult to attract and gain electrons

Question 39

Why do elements become more reactive as you move down the column (group 1)

Answer 39

Reactivity increases Atoms get larger This means the outer electrons become further away/less attracted to the nucleus and become easier to lose outer electrons

Question 40

Mendeleev left spaces marked with an asterisk He left these spaces because he thought missing elements belonged there Why did Mendeleev's periodic table become more widely accepted than previous versions?

Answer 40

He predicted properties of missing elements The gaps were filled with new elements that were discovered Properties of these elements matched the predicted ones

Question 41

Modern name for atomic weight

Answer 41

RAM

Question 42

Describe what you would see when sodium reacts with chlorine

Answer 42

Flame Colour of gas fades White solid forms