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aqa chemistry > Topic 1- Atomic Structure and the Periodic Table > Flashcards

Topic 1- Atomic Structure and the Periodic Table Flashcards

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AP® Chemistry flashcards Periodic Table flashcards
1
Q

What is an atom?

A

An atoms is the smallest part of an element. All matter is made of atoms.

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2
Q

What is a compound?

A

Compounds contain two or more elements chemically bonded in fixed proportions.

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3
Q

What is a mixture?

A

• A mixture consists of two or more elements or compounds not chemically bonded.
• The chemical properties of the substances in the mixture do not change.

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4
Q

How can compounds be seperated?

A

Compounds can only be separated into elements by chemical reactions.

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5
Q

How can mixtures be seperated?

A

• Mixtures can be seperated by processes such as filtration, crystallisation, simple distillation and chromatography.
• These processes don’t involve chemical reactions and no new substances are made.

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6
Q

What were atoms thought to be before the discovery of the electron?

A

Atoms were thought to be tiny spheres that could not be divided

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7
Q

What did the discovery of the electron lead to?

A

• The plum pudding model of the atom.
• The plum pudding model suggested that the atom is a ball of positive charge with electrons embedded in it.

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8
Q

What did the results of the alpha scattering experiment lead to?

A

• The results from the alpha particles scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged.
• This nuclear model replaced the plum pudding model.

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9
Q

How big is an atom?

A

0.1 nanometres in diameter

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10
Q

How big is the nucleus?

A

Approximately 1/10000 the size of the atom

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11
Q

What does the nucleus consist of?

A

Protons and neutrons

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12
Q

Where are electrons located?

A

Electrons orbit the nucleus in the electron shells

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13
Q

Relative charges of the sub-atomic particles

A

• Proton: +1
• Neutron: 0
• Electron: -1

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14
Q

Relative masses of the sub-atonic particles

A

• Proton: 1
• Neutron: 1
• Electron: (essentially) 0

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15
Q

What is the atomic number? (number at the bottom)

A

The number of protons (number of protons is the same as number of electrons)

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16
Q

What is the mass number? (number at the top)

A

The sum of the number of protons and neutrons

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17
Q

Who discovered the first known subatomic particle and what is it?

A

JJ Thomson discovered the electron.

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18
Q

Plum pudding model

A

• In this model, the atom is considered to be a solid sphere with a weakly positive charge.
•Negatively charged electrons are embedded into this solid sohere.

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19
Q

Who discovered the nucleus?

A

Ernest Rutherford discovered the existence of the nucleus in the alpha particle scattering experiment.

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20
Q

Why was the plum pudding model rejected?

A

With the discovery of the nucleus, atoms could no longer be considered as solid spheres, so the accepted model changed to the nuclear model.

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21
Q

The nuclear model

A

• Atoms consist of a tiny central nucleus that is dense, indivisible and strongly positively charged.
• The nucleus is surrounded by negatively charged electrons.
• Most of the atom in this model is actually empty space, with the mass being concentrated in the nucleus.

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22
Q

What did Niels Bohr’s calculations suggest?

A

His calculations suggested that the Nuclear model would be unstable if electrons simply surrounded the nucleus.

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23
Q

Why did the nuclear model change to the orbital model?

A

Niels Bohr’s predictions were verified by experimental data, so the accepeted model changed to the Orbital model.

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24
Q

The orbital model

A

• Tiny, dense, indivisible positive nucleus.
• Electrons orbit in electron shells at fixed distances from the nucleus.
• The energy of electrons is lower in the shells closer to the nucleus.

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25
Q

Modern Atomic Model

A

• Tiny central nucleus (made up of positive protons and chargeless neutrons).
• Orbited by very tiny, negative electrons.

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26
Q

What did Rutherford subsequently discover?

A

He discovered that the positive charge of the nucleus could be divided into equally charged units, which he called protons.

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27
Q

What did Chadwick disover?

A

Chadwick discovered that the additional mass of the nucleus could be divided into equal units with no electrical charge, which he called neutrons.

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28
Q

What did Chadwick’s and Rutherford’s discoveries show?

A

These two discoveries showed that the nucleus itself was not indivisible, so the acvepeted model had to change.

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29
Q

Alpha Particle Scattering Experiment

A

• This experiment provided the evidence that led to the replacement of the Plum Pudding model with the Nuclear model.
• If the Plum Pudding model was correct, the alpha radiation should easily pass straight through the gold and be detected on the other side.
• Rutherford obtained very unexpected results. Most of the radiation did pass through the gold foil as expected, but some was significantly deflected, and some actually reflected back towards the radioactive material.

30
Q

What is an alpha particle?

A

Small particles that are positively charges, have a large ,ass.

31
Q

What was the first scenario that could explain the alpha scattering observed?

A
  1. The atom must be made up of mostly empty space.
32
Q

What was the second scenario that could explain the alpha scattering observed?

A
  1. The atom must have a tiny central nucleus that has a strong positive charge.
33
Q

What was the third scenario that could explain the alpha scattering observed?

A
  1. The nucleus must be very dense.
34
Q

What is an isotope?

A

Atoms of the same element that have different number of neutrons.

35
Q

What is the relative atomic mass

A

An averaged value of atomic mass which incorporates both the abundance and mass number of all known isotopes.

36
Q

What happens during a chemical reaction?

A

Chemical bonds in the reactants are broken and new chemical bonds are made to form the products. The atoms themselves remain unchanged in the chemical reaction, only the bonding changes.

37
Q

Conservation of mass

A

Mass of the reactants is equal to the mass of products.

38
Q

Solution

A

A mixture of a liquid (solvent) and one or more dissolved solids (solutes.

39
Q

Solvent

A

A liquid that dissolves certain solutes to make a solution

40
Q

Solute

A

A solid that can be dissolves in solvent to make a solution

41
Q

Soluble

A

Can be dissolved in a given solvent

42
Q

Insoluble

A

Can not be dissolves in a given solution

43
Q

Filtration method

A

• Filter paper is folded into a cone, and insterted into the neck of a filter funnel.
• This is placed into a conical flask, and the mixture is slowly poured into the filter funnel.
• The filter paper is designed to allow liquids to pass through, but to prevent solids from passing through so the insoluble solid (residue) and liquid (filtrate) are seperated.

44
Q

Distillation method

A

• The solution is poured into a round-bottomed flask, connected to a water-cooled condesner all in a closed system to prevent the loss of gasses.
• Solution is heated causing the liquid solvent to boil and evaporate.
• The gas passes through the condenser, is cooled, and condenses back into a liquid (called the distillate), which is collected.
• The solid solute remains as a residue on the inside of the round-bottomed flask.

45
Q

Crystallisation Method

A

• Solution is poured into an evaporating basin and gently heated, causing liquid solvent to evaporate, until crystals start to form.
• The evaporating basin is then removed from the heat and allowed to slowly cool, encouraging the formation of crystals of the solute in residual solution.
• Once cool, any remaining solution can be removed by filtration, and the crystals patted dry.

46
Q

Fractional distillation method

A

• Mixture of liquids is poured into a round-bottomed flask, connected to a water-cooled condesner.
• The mixture is heated, and the temperature of the mixture reached a point where it equals the lowest boiling point in the mixture.
• The liqquid with that boiling poiny in the mixture turns into a gas and passes through the condenser, where it is cooled and condenses back into a liquid.
• The temperature is kept constant during this process until no more liquid boils off.
• This liquid (fraction) can then be collected.
• Once all lf the first fraction has been collected, the temperature is raises until it reaches the next lowest boiling point, and the process is repeated to collect the rest of the fractions.
• This is repeated until all of the liquids in the mixture have been seperated by their boiling point.

47
Q

Who made the modern periodic table?

A

Dmitri Mendeleev

48
Q

How were elements categorised before the periodic table?

A

• By physical and chemical properties
• Their atimic weight

49
Q

What discovery was made after ordering elements in atomic weight?

A

Every eight element had similar properties (law of octaves).

50
Q

How did Mendeleev overcome some of the problems of early periodic tables?

A

• He put the elements in order of atomic weight but switched them if the properties meant it should be changed.
• Gaps were left in the table to make sure that elements with similar properties stayed in the same group. Some of these gaps indicated the existence of undiscovered elements and allowed Mendeleev to predict what their properties might be. When they were found and they fitted the pattern it helped comfirm Mendeleev’s ideas.

51
Q

What did the discovery of isotopes confirm?

A

• It 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 element have different masses but have the same chemical properties so occupy the same position on the periodic table.

52
Q

What are the properties of metals?

A

• Shiny
• Hard
• Malleable
• Dense
• Good electrical and thermal conductors
• Soilds at room temperature

53
Q

How do metal atoms react?

A

Metal atoms typically gain a full outer shell by losing electrons.

54
Q

What are the non-metal properties?

A

• Dull
• Non-conductive
• Brittle
• Less dense
• Gases/liquids at room temperature

55
Q

How do non-metals react?

A

They typically gain a full outer shell by gaining or sharing electrons.

56
Q

What are the properties of transition metals?

A

• Show all of the general properties of metals, but have useful additional properties
• Can form coloured compounds in chemical reactions
• They can act as catalysts
• They can lose different numbers of electrons in different chemical reactions.

57
Q

What are the properties of alkali metals?

A

• React with water to produce metal hydroxide solutions
• Alkali Metal + Water —> Metal Hydroxide + Hydrogen
• React with acids to produce salts and hydrogen gas
• Alkali Metal + Acid —> Salt + Hydrogen
• React with oxygen to produce megal oxides
• Alkali Metal + Oxygen —> Metal oxide
• React with halogens (group 7) to produce salts
• Alkali Metal + Halogen —> Salt

58
Q

What are the reactivity trends of group 1?

A

• The chemical reactivity of the alkali metals increases down group 1.
• Lower melting and boiling points
• Higher relative atomic mass

59
Q

What flame does potassium burn with?

A

Lilac flame

60
Q

How do alkali metals react?

A

They lose their outer electron to gain a full outer shell. As the number of electron shells increases down group 1, the outer electron becomes easier to lose, and the resctivity increases.

61
Q

How do group 1 metals react with chlorine?

A
  1. Group 1 metals react vigorously when heated in chlorine gas to form white metal chloride salts.
  2. As you go down the group, reactivity increases so the reaction with chlorine gas gets more vigorous.
62
Q

How do group 1 metals react with oxygen?

A

• Lithium reacts to form lithium oxide (Li2O)
• Sodium reacts to form a mixture of sodium oxide (Na2O) and sodium peroxide (Na2O2)
• Potassium reacts to form a mixture of potassium peroxide (K2O2) and potassium superoxide (KO2)

63
Q

What are the colours of the halogens?

A

• Fluorine is a yellow gas.
• Chlorine is a green gas.
• Bromine is a red-brown liquid.
• Iodine is a dark grey crystalline solid or a purple vapour.

64
Q

What are the reactivity trends of group 7? (Halogens)

A

As you go down Group 7, the halogens:
• becomes less reactive, have a higher melting and boiling ooints, have higher relative atomic masses.

65
Q

Why does the reactivity decrease as you go down group 7? (Halogens)

A

Because it’s harder to gain an extra electron, because the outer shell’s further from the nucleus.

66
Q

Why do all the group 7 elements react in a similar way?

A

Because they all have 7 outer shell electrons.

67
Q

How do halogens react with non-metals?

A

• They share electrons to achieve a full outer shell.
• The compounds that form when halogens react with non-metals all have simple molecular structures.

68
Q

How do halogens react with metals?

A

• The halogens form 1- ions called halides when they bond with metals
• The compounds that form have an ionic structure

69
Q

How do halogens react with each other?

A

A displacement reaction can occur between a more reactive halogen and the salt of a less reactive hydrogen.

70
Q

What are the properties of group 0? (Noble gases)

A

• They all have 8 electrons in their outer-shell, **apart from helium which has two **, which gives them a full outer-shell.
• They exist as monoatomic gases- single atoms not bonded to each other.
• All elements in Group 0 are colourless gases at room temperature.
• As the noble gases are inert they’re non-flammable- they won’t set on fire.

71
Q

What are the patterns in the properties of noble gases?

A

• Boiling points increase as you move down the group.
• Relative atomic mass increases as you move down the group.

72
Q

Why does the boiling point increase as you go down group 0? (Noble gases)

A

Due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome.

aqa chemistry (10 decks)

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