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Chemistry > Atomic structure and the periodic table > Flashcards

Atomic structure and the periodic table Flashcards

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1
Q

What is an element?

A

An element is a substance made of atoms that all contain the same number of protons and cannot be split into anything simpler.

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2
Q

What are the 7 diatomic elements

A

H2, N2, O2, F2, Cl2, Br2 and I2.

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3
Q

Define a compound

A

A compound is a pure substance made up of two or more elements chemically combined and which cannot be separated by physical means

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4
Q

Name 7 covalent compounds

A

H2SO4 is sulfuric acid
NH3 is ammonia
CH4 is methane
HCl is hydrochloric acid (or hydrogen chloride if it is a gas)
C6H12O6 is glucose
C2H5OH is ethanol
HNO3 is nitric acid

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5
Q

Law of Conservation of Mass

A

The total mass of reactants is always equal to the total mass of products

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6
Q

What are ions which are present but do not take part in reactions called?

A

Ions which are present but do not take part in reactions are called spectator ions

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7
Q

Do mixtures change chemical properties?
Can they be separated by physical or physical processes?

A

Each constituent of the mixture retains its chemical properties
The parts of a mixture are not chemically bonded together and so they can be separated by physical means

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8
Q

When is filtration used?

A

Filtration is used to separate an insoluble solid from a liquid

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9
Q

Describe the steps of filtration (4 steps)

A

-A piece of filter paper is placed in a filter funnel above a beaker
-A mixture of insoluble solid and liquid is poured into the filter funnel
-The filter paper will only allow small liquid particles to pass through as filtrate
-Solid particles are too large to pass through the filter paper so will stay behind as a residue

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10
Q

When is crystallisation used?

A

Crystallisation is used to separate a soluble solid from a liquid

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11
Q

Describe the steps of crystallisation (4 steps)

A

-Solution is heated to allow the solvent to evaporate
-To test if the solution is saturated a clean, dry, cold glass rod is dipped into the solution
If the solution is saturated, crystals will form on the glass rod
-The saturated solution is then allowed to cool slowly
Crystals begin to grow as solids come out of solution due to decreasing solubility
-The crystals are collected by filtering the solution, they are washed with cold distilled water to remove impurities and are then allowed to dry

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12
Q

When can simple distillation be used instead of fractional distillation?

A

Simple distillation is used to separate mixtures which are having boiling points with a gap of a minimum of 50 degrees.

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13
Q

When can simple distillation be used?

A

-This is used to separate a liquid and soluble solid from a solution (e.g., water from a solution of salt water) or a pure liquid from a mixture of liquids

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14
Q

4 steps for simple distillation

A

-The solution is heated and a liquid evaporates producing a vapour which rises through the neck of the round-bottomed flask (e.g. for saltwater, this would be water boiling at 100 oC)
-The vapour passes through the condenser, where it cools and condenses, turning into the pure liquid that is collected in a beaker
-After all the liquid is evaporated from the solution, only the solid solute will be left behind

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15
Q

When is fractional distillation used?

A

This is used to separate two or more liquids that are miscible with one another

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16
Q

Give the 4 steps of fractional distillation

A

-solution is heated to the temperature of the substance withe lowest BP
-This substance will rise and evaporate first, and vapours will pass through a condenser, where they cool and condense, turning into a liquid that will be collected in a beaker
-All of the substance is evaporated and collected, leaving behind the other components(s) of the mixture

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17
Q

When is paper chromatography used?

A

This technique is used to separate substances that have different solubilities in a given solvent

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18
Q

Give the 4 steps of fractional distillation

A

-A pencil line is drawn on chromatography paper and spots of the sample are placed on it
-The paper is then lowered into the solvent container, making sure that the pencil line sits above the level of the solvent, so the samples don’t wash into the solvent container
-The solvent travels up the paper by capillary action, taking some of the coloured substances with it
-Different substances have different solubilities so will travel at different rates, causing the substances to spread apart
Those substances with higher solubility will travel further than the others

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19
Q

List the order of the scientific discoveries related to the atom (5 key people)

A

Dalton-‘billiard ball mode’ indivisible
Thomson-‘plum pudding model’ electron
Rutherford-‘nuclear atom’ empty space and electrons orbiting nucleus in fixed paths
Bohr-‘planetary model’-electrons orbit the nucleus in orbitals (set distances) from nucleus
james chadwick-proposed the neutron

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20
Q

2 pros and 2 cons of Daltons model

A

pros: roughly spherical, limited amount of elemnets
cons: don’t tell us about electrical nature of atoms, continuous atoms

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21
Q

2 pros and cons of thomsons model

A

pros: accounts for electrical nature of an atom, discontinuous atom
cons: Low density of alpha particle can’t explain the bouncing back of alpha particles in gold foil experiment

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22
Q

2 pros and cons of rutherfords model

A

pros: Dense nucleus explains the bouncing back of alpha particles in the gold foil scattering experiment
cons: failed to explain stability of elctrons in circular path

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23
Q

radius of an atom

A

0.1nm

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24
Q

How many times smaller than the radius of the atom is the radius of the nucleus?

A

10,000

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25
Q

How do chemical properties vary across different isotopes of an element

A

Isotopes display the same chemical characteristics

26
Q

How to calculate the relative atomic mass of each element in a chemical formula.

A

(%isotope abundance of isotope x mass of isotope)/100

27
Q

How are elements arranged in the periodic table arranged?

A

In order of increasing atomic number

28
Q

How were elements arranged in their early periodic tables?

A

In order of atomic weight

29
Q

How did Mendeleev arrange elements in his periodic table (5 points)

A

-he placed elements with similar properties in the same group
-arranged horizontally in order of increasing atomic weight
-left gaps for elements he thought were still to be discovered
-He used the properties and trends of other elements to predict the properties of these undiscovered elements
-His table wasn’t completely accurate as he hadn’t accounted for isotopes

30
Q

Ionic difference between metals and non-metals

A

Metals form positive ions, non-metals form negative ions

31
Q

Which metal is not solid at room temperature?

A

mercury

32
Q

Metals vs non-metals: Bonding

A

Metals have metallic bonding due to loss of outer shell electrons. Non-metals have covalent bonding

33
Q

Use of helium

A

Helium is used for balloons as it is lighter than air and is a noble gas so won’t burn

34
Q

Use of neon + xenon

A

Advertising signs

35
Q

uses of argon (3)

A

-advertising signs
-inert atmosphere for welding
-Argon is also used to fill light bulbs, as like the other noble gases, it has the unusual property of glowing brightly when a high potential difference is applied to the gas under low pressure

36
Q

Trend in BP in group 0?

A

-Increases with relative atomic mass down the group
-This leads to an increase in intermolecular forces between atoms, increasing the amount of energy needed to overcome these forces to change state

37
Q

What is the name of the element with the lowest BP?

A

Helium at -269°c

38
Q

Trends in Density down group 0

A

It increases

39
Q

Trends in density in group 1?
Which element is the exception?

A

It increases down the group. Potassium is the exception; it has a lower density than sodium

40
Q

Why does reactivity increase down group 1?

A
  • The outermost electron gets further away from the nucleus, so there are weaker forces of attraction between the outermost electron and the nucleus
  • Less energy is required to overcome the force of attraction as it gets weaker, so the outer electron is lost more easily
  • So, the alkali metals get more reactive as you descend the group
41
Q

Reaction between alkali metal and water

A

Alkali metal+water→metal hydroxide + hydrogen

42
Q

Reaction between alkali metal and oxygen

A

alkali metal + oxygen→ metal oxide

43
Q

Reaction between alkali metal and chlorine

A

alkali metal + chlorine → metal chloride

44
Q

What makes halogens dangerous

A

they are poisonous gases

45
Q

What word is used to describe their natural state

A

diatomic

46
Q

FLUORINE: state+colour (R.T.P.), characteristics, colour in solution

A

yellow gas, poisonous and very recative, doesn’t reactive with water as it oxidises water

47
Q

CHLORINE: state+colour (R.T.P.), characteristics, colour in solution

A

pale yellow-green gas, reactive poisonous dense gas, pale green

48
Q

BROMINE: state+colour(R.T.P.), characteristics, colour in solution

A

red-brown liquid, dense red-brown volatile liquid, orange

49
Q

IODINE: state+colour(R.T.P.), characteristics, colour in solution

A

Purple-black solid, shimmery crystalline solid which sublimes to form a purple vapour, dark brown

50
Q

Explain the trend in BP down the halogens

A

Icreases- this is due to increasing intermolecular forces as the atoms become larger, so more energy is required to overcome these forces

51
Q

Trend in reactivity down group 7

A

It decreases bcz:
-as you go down the group there are more shells
-so the outer electrons are furthest from the nucleus
-Halogens need to GAIN AN ELECTRON
-the increased distance between the nucleus and the outer shell makes it harder to attract electrons

52
Q

What happens if you add chlorine solution to colourless potassium bromide or potassium iodide

A

A displacement reaction occurs. The solution becomes orange/brown as bromine/iodine is formed

53
Q

Explain what you will see when bromine displaces iodine

A

Brown solution

54
Q

What happens to the rate of reaction down group 7

A

The rate of reaction is slower for halogens which are further down the group such as bromine and iodine

55
Q

Do non-metals react with the halogens

A

yes

56
Q

Properties of transition metals (4)

A

hard, strong, good conductors, form coloured compounds, highly dense

57
Q

Uses of transition metals

A

-catalysts
-medicine
-paint
-jewellry

58
Q

Difference between transition metals and alkali metals: charge

A

Alkali metals form 1+ charge. Transition metals form variable charges

59
Q

Difference between transition metals and alkali metals: density

A

Transition metals are much denser

60
Q

Difference between transition metals and alkali metals: Reactivity

A

Alkali metals are more reactive whereas transition metals either react very slowly or not at all

Chemistry (4 decks)

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