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Chemistry > Topic 1-Atomic Structure and the Periodic Table > Flashcards

Topic 1-Atomic Structure and the Periodic Table Flashcards

1
Q

What methods are there to separate mixtures?

A 
Filtration
Crystallisation
Simple distillation
Fractional distillation
Chromatography
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2
Q

What was the plum pudding model?

A

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

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3
Q

What was Rutherford’s alpha particle scattering experiment?

A

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)

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4
Q

What was concluded after the particle scattering experiment?

A

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

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5
Q

Who suggested that electrons orbited the nucleus at specific distances?

A

Niels Bohr

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6
Q

How did James Chadwick contribute to the atom model?

A

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

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7
Q

What is the radius an atom?

A

0.1nm

1x10^-8cm

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8
Q

What is the radius of a nucleus?

A

1x10^-14

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

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9
Q

What are isotopes?

A

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

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10
Q

How do you calculate relative atomic mass?

A

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

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11
Q

Describe and explain chromatography

A

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.

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12
Q

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

A

Pen ink is soluble and will dissolve in the solvent

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13
Q

In chromatography, what is the end result called?

A

It is called a chromatogram

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14
Q

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

A

This is to stop the solvent from evaporating

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15
Q

Describe and explain simple distilation

A

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

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16
Q

What is the problem with simple distilation?

A

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

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17
Q

Describe and explain fractional distilation

A

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

18
Q

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

A

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

19
Q

Describe and explain filtration

A

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

20
Q

Describe and explain crystallisation

A

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

21
Q

What is a separating funnel?

A

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

22
Q

Who created the periodic table?

A

Dmitri Mendeleev in 1869

23
Q

How did Mendeleev arrange the periodic table?

A

He ordered elements in order of increasing atomic mass

24
Q

What was special about Mendeleev’s periodic table?

A

He had left gaps for undiscovered elements

He showed elements with similar chemical properties lined up in groups

25
Q

Arrangements by atomic mass provided Mendeleev with some elements that didn’t fit the patten, such as Argon.

Explain how this problem was overcome

A

Table was arranged by atomic number

Discovery of isotopes

26
Q

Alcohols are flammable

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

A

Heat the mixture using a water bath

27
Q

Name some apparatus used during distillation

A 
Thermometer
Condenser
Round-bottom flask
Clamp/clamp stand
Fractional column
28
Q

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

A

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

29
Q

Describe what you would see when sodium is added to water

A

Fizz/Effervescence

Floats

Melts

Dissolves

30
Q

Explain the trend in reactivity of group 1 metals with water

A

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

31
Q

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

A

One electron on the outer shell

Forms ions with 1+ charge

32
Q

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?

A

They have similar properties

Iodine is diatomic

They have similar reactivity

33
Q

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

A

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

34
Q

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

A

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

35
Q

What are some properties of noble gases?

A

Colourless gases

Very low melting points

Poor conductors

Non-flammable

Very unreactive

36
Q

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

A

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

37
Q

What are some physical properties of halogens?

A

Low melting and boiling points

Poor conductors

Toxic

Coloured

38
Q

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

A

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

39
Q

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

A

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

40
Q

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?

A

He predicted properties of missing elements

The gaps were filled with new elements that were discovered

Properties of these elements matched the predicted ones

41
Q

Modern name for atomic weight

A

RAM

42
Q

Describe what you would see when sodium reacts with chlorine

A

Flame
Colour of gas fades
White solid forms

Chemistry (10 decks)

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