Topic 1 - Atomic Structure and the Periodic Table Flashcards

1
Q

How big are atoms

A

0.1 nanometers (1 x 10^-10)

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2
Q

What is the nucleus

A

-Middle of the (almost whole mass of atom is concentrated here)
-Contains protons and neutrons
-Radius of 1 x 10^-14m
-Positive charge because of protons

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3
Q

What are electrons

A

-Around the nucleus in electron shells
-Tiny and negatively charged
-Have virtually no mass

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4
Q

What is the relative mass of each particle

A

Proton - 1
Neutron - 1
Electron - Very small

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5
Q

What is the charge of each particle

A

Proton - +1
Neutron - 0
Electron - -1

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6
Q

Why are atoms are neutral

A

Have the same number of protons and electrons so the charges cancel out

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7
Q

What is an ion

A

An atom that has lost or gained electrons so has an overall charge

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8
Q

What is the atomic number of an atom

A

How many protons there are (bottom of nuclear symbol)

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9
Q

What is the mass number of an atom

A

The total number of protons and neutrons in the atom (top of the nuclear symbol)

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10
Q

What particle decides what element an atom is

A

The number of protons in the nucleus

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11
Q

What are elements

A

If a substance only contains atoms with same number of protons

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12
Q

What are isotopes

A

Different forms of the same element which have the same number of protons but different number of neutrons so they have the same atomic number and different mass number

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13
Q

What is relative atomic mass

A

An average mass taking into account the different masses and abundances of all the isotopes that make up the element

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14
Q

What is the equation for relative atomic mass

A

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

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15
Q

What are compounds

A

Substances formed with two or more elements held together by chemical bonds

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16
Q

Why can mixtures be easily seperated

A

There’s no chemical bonds between the parts of a mixture

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17
Q

Outline how to do paper chromatography

A
  1. Draw a line near the bottom of a sheet of filter paper (use pencil)
  2. Add a spot of ink to the line and place the sheet in a beaker of solvent
  3. The solvent used depends on what’s being tested. Some dissolve in water but sometimes other solvents, like ethanol are needed
  4. Make sure ink isn’t touching solvent
  5. Place a lid on top of the container to stop the solvent evaporating
  6. Solvent seeps up paper, carrying the ink with it
  7. Each different dye will move at a different rate so the dyes will separate out
  8. If any of the dyes is insoluble it will stay on the baseline
  9. When the solvent has reached nearly the top take the paper out of the beaker and leave it to dry
  10. The end result is a pattern of spots called a chromatogram
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18
Q

When is filtration used

A

-If a product is an insoluble solid that needs to be separated from a liquid reaction mixture
-Purification (solid purities in a reaction can be separated)

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19
Q

What are the two methods for separating soluble salt from a solution

A

Evaporation and crystallisation

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20
Q

Outline evaporation for separating a soluble salt from a solution

A

-Poir solution into evaporating dish
-Heat slowly and the solvent will evaporate and the solution will get more concentrated. Eventually crystals will start to form.
-Keep heating the dish until all you have left are dry crystals

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21
Q

Outline how to use crystallisation to separate salt from a solution

A

-Pour solution into evaporating dish and gently heat the solution. Some will evaporate and the solution will get more concentrated
-Once solvent has evaporated or when crystals start to form, remove dish from heat and leave the solution to cool
-The salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
-Filter the crystals out Of the solution and leave them in a warm place to dry or a drying oven, or a desiccator

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22
Q

How to separate rock salt

A

-Grind the mixture to make sure the salt crystals are small
-Put mixture into water and stir. The salt will dissolve, but the sand won’t
-Filter the mixture and the grains of sand won’t fit so they will collect on the paper. The salt passes through the paper we if it’s a part of the solution.
-Evaporate the water from salt so that it forms dry crystals

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23
Q

Outline simple distillation

A

-The solution is heated. The part of the solution that has the lowest boiling point evaporates first
-The vapour is then cooled, condensed in the condenser and is collected
-The rest of the solution is left behind in the flask

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24
Q

What is the problem with simple distillation

A

You can only use it to separate things with very different boiling points - if the temperature goes higher than the boiling point of the substance with the higher boiling point, they will mix again

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25
Q

When is fractional distillation used

A

If you need to separate out a mixture of liquids

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26
Q

Outline fractional distillation

A

-Put your mixture in a flask and put a fractioning column on top and then heat it
-The different liquids will all have different boiling points so they will evaporate at different temperatures
-The liquid with the lowest boiling point evaporates first. When the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column
-Liquids with higher boiling points might also start to evaporate. But the column is cooler towards the top. So they will only get part of the way up before condensing and running back down towards the flask
-When the first liquid has been collected you raise the temperature until the next one reaches the top

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27
Q

What is the plum pudding model

A

A model that shows atoms to be a ball of positive charge with electrons stuck in it

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28
Q

What did Rutherford expect to happen during the alpha particle scattering experiment

A

The particles to pass straight through the sheet or be slightly deflected at most. This was because of the positive charge of each atom was thought to be very spread out through the pudding of the atom

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29
Q

What happened during the alpha particle scattering experiment

A

Most went straight through the gold sheet, some were deflected more than expected and a small number were deflected backwards

30
Q

What did the alpha particle scattering experiment prove

A

The plum pudding model wasn’t right

31
Q

How did Rutherford explain the evidence found from the alpha scattering experiemnt

A

He came up with the nuclear model of the atom. There’s a tiny, positively charged nucleus at the centre, where most of the mass is concentrated. A ‘cloud’ of negative electrons surrounds this nucleus - so most of the atom is empty space. When alpha particles came near the concentrated, positive charge of the nucleus they were deflected. If they were fired directly at the nucleus, they were deflected backwards

32
Q

What did Niehls Bohr propose about the atom

A

That electrons orbit the nucleus in fixed shells and aren’t anywhere in between. Each shell is a fixed distance from the nucleus.

33
Q

How were protons discovered

A

Rutherford and other experimented showing that the nucleus can be divided into smaller particles which each have the same charge as a hydrogen nucleus. These particles were named protons.

34
Q

How were neutrons discovered

A

James Chadwick carried out an experiment which provided evidence for neutral particles in the nucleus (neutrons)

35
Q

What did the discovery of neutrons result in

A

A model of the atom which was pretty close to the modern day accepted version, known as the nuclear model

36
Q

How were elements arranged in the early 1800s

A

In order of atomic weight and when this was done a periodic pattern was noticed in the properties of the elements. This meant that some elements were in the wrong group as their properties not taken into account

37
Q

What did Mendeleev for the periodic table

A

-In 1869 overcame some problems by taking 50 known elements and arranging them into his Table of Elements with various gaps as shown
-He put elements mainly in order of atomic weight but switch the ordered if the properties meant it should be changed

38
Q

What proved Mendeleevs ideas

A

-As he left gaps to make sure that elements with similar properties stayed in the same groups.
-Some gaps indicated existence of undiscovered elements allowing Mendeleev to predict what their properties might be
-When found they fitted the pattern confirming his ideas

39
Q

Give an example of an element that confirmed Mendeleev’s

A

He made good predictions about the chemical and physical properties of an elements he called ekasilicon which is now known as germanium

40
Q

How did isotopes help confirm Mendeleevs

A

When discovered in the early 20th century confirmed that Mendeleev was correct to not place elements in a strict order of atomic weight but to also take account of their properties. Isotopes of the same elements have different masses but have the same chemical properties so occupy the same position on the periodic table

41
Q

How is the periodic table arranged

A

The elements are laid out in order of increasing atomic number. Arranging the elements like this means there are repeating patterns in the properties of the elements.

42
Q

What do groups in the periodic table tell us

A

How many electrons in the outer shell. (E.g. Group 1 elements all have one electron in their outer shell)

43
Q

What is an exception to the group rule on the periodic table

A

-Group 0

44
Q

How can you predict properties of an element in the same group as another

A

If you know the properties of one element in a group you can predict others in the same group as elements in the same group have similar properties. (E.g. group 1 elements are all metals and they react in a similar way)

45
Q

Give examples of trends in reactivity

A

-In group 1 the metals are more reactive as you down the group
-In group 7 reactivity decreases as you go down the group

46
Q

What do metals do when they react

A

They form positive ions when they react.

47
Q

Generally what happens to non-metals when they react

A

Don’t generally form positives ions

48
Q

Why is it easier for metals to form ions

A

Not much energy is needed to remove the electrons as the outer electrons are a long way from the nucleus so feel a weaker attraction

49
Q

Why is it more difficult for non-metals to form positive ions

A

As they are either to the right of the periodic table where they have lots of electrons to remove to get a full outer shell or towards the top where the electrons are close to the nucleus so feel a strong attraction

50
Q

What does metallic bonding cause in metals (properties)

A

-Strong but can be bent or hammered into different shapes
-They’re great at conducting heat and electricity
-They have high boiling and melting points

51
Q

As non-metals don’t have metallic bounding what properties do they have

A

-Dull looking
-More brittle
-Aren’t always solids At room temperature
-Don’t generally conduct electricity and often have a lower density

52
Q

What are transition metals

A

-They’re good conductors of heat and electricity and they have high density, are strong and shiny
-They have more then one ion. (E.g. Copper forms Cu+ and Cu2+
-Often coloured and so compounds that contain them are colourful
-Often make good catalysts.

53
Q

What are the trends for alkali metals as you go down Group 1

A

-Increasing reactivity
-Lower melting and boiling points
-Higher relative atomic mass

54
Q

Give properties of alkali metals

A

-Very reactive as they have one electron in their electron shell
-All soft and have low density

55
Q

What happens when an alkali metal reacts with water

A

-When Group 1 metals are put in water, they react vigorously to produce hydrogen gas and metal hydroxide
-The more reactive an alkali metal is the more violent the reaction
-The amount of energy given out by the reaction increases down the group

56
Q

What happens when alkali metals react with chlorine

A

-Group 1 metals react vigorously when heated in chlorine gas to form white metal chloride salts
-As you go down the group, reactivity increases so the reaction with chlorine gets more vigorous

57
Q

What happens when alkali metals react with oxygen

A

-Lithium reacts to form lithium oxide
-Sodium reacts to form a mixture of sodium oxide and sodium peroxide
-Potassium reacts to form a mixture of potassium peroxide and potassium superoxide

58
Q

What are the different properties between group 1 and transition

A

-G1 are much more reactive (react more vigorously with water, oxygen or group 7)
-G1 are less dense, strong and hard than the transition metals and have much lower melting
points

59
Q

What is fluorine

A

A very reactive, poisonous yellow (halogen)

60
Q

What is chlorine

A

a fairly reactive, poisonous dense green gas (halogen)

61
Q

What is bromine

A

A dense, poisonojs red-brown volatile liquid (halogen)

62
Q

What is iodine

A

Is a dark grey crystalline solid or a purple vapour

63
Q

How do halogens exist

A

As molecules in pairs

64
Q

What are trends in group 7

A

-Become less reactive as you down
-Have higher melting and boiling points
-Have higher relative atomic masses

65
Q

How do halogens form molecular compounds

A

The atoms share electrons via covalent bonding with other non-metals so as to achieve a full outer shell. The compounds that form when halogens react with non-metals all have simple molecular structures

66
Q

What do halogens form when they react with metals

A

They form halides (1- ions)

67
Q

When does a displacement reactions happen between halogens

A

Can occur between a more reactive halogen and the salt of a less reactive one

68
Q

What elements are in group 0 and give examples

A

Noble gases (e.g. neon, helium and argon)

69
Q

What properties do group 0 elements have

A

-They all have eight electrons in their outer energy level apart from helium which has a full outer shell
-As they don’t need to give up or gain electrons for a full outer shell they don’t react much at all
-They act as single atoms not bonded
-Colourless gases at room temperature
-As they are inert they’re non-flammable

70
Q

What are the trends in noble gas

A

-The boiling points of the noble gases increase as you move down the group along with increasing relative atomic mass
-The increase in boiling point is due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome.