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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 atom?

A

An atom is the smallest part of an element that can exist.

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2
Q

How many different elements are there and where are they shown?

A
  1. Periodic table.
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3
Q

What are the properties of the nucleus?

A
  • in the middle of the atom
  • contains protons and neutrons
  • has a positive charge because of the protons
  • the hole mass of the atom is concentrated in the nucleus
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4
Q

What are the properties of the electron?

A

They move around the nucleus in electron shells.
They’re negatively charged and tiny. They have virtually no mass.

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5
Q

Why are atoms neutral?

A

They have the same number of protons as electrons
The charge on the electrons is the same size as the charge on the protons but opposite.
In an ion, the number of protons does not equal the number of electrons.
This means it has an overall charge.

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6
Q

What does the atomic number tell you and how do you identify it?

A

The number of protons. It’s the smaller number.

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7
Q

What does the mass number tell you and how do you identify it?

A

The total number of protons and neutrons in the atom. It is the bigger number

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8
Q

What is an element?

A

A substance made up of atoms that all have the same number of protons in their nucleus.

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9
Q

What are isotopes?

A

Different forms of the same element, which have the same number of protons but different number of neutrons.

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10
Q

Formula for relative atomic mass of an isotope.

A

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

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11
Q

What is a compound?

A

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

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12
Q

What do chemical reactions always involve?

A

The formation of one or more new substances.

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13
Q

What do chemical reactions often involve?

A

A detectable energy change.

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14
Q

How can compounds be separated only?

A

Chemical reactions

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15
Q

What is a mixture of?

A

Consists of two or more elements or compounds not chemically combined together.

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16
Q

What happens to the chemical properties of each substance in the mixture.

A

They are unchanged.

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17
Q

How can mixtures be separated?

A

Physical processes - filtration, distillation (simple, fractional), chromotography, crystallisation.

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18
Q

When is filtration used?

A

If product is an insoluble solid inside a liquid.

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19
Q

When is crystallisation and evaporation used?

A

Seperate soluble solids from solutions.

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20
Q

When is chromatography used?

A

Seperate different dyes in an ink.

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21
Q

What do you use to separate rock salt?

A

Filtration and Crystallisation.

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22
Q

When is distillation used?

A

To separate a liquid from a solution.

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23
Q

When is fractional distillation used?

A

To separate a mixture of liquids.

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24
Q

What may lead to a scientific model being changed or replaced?

A

New experimental evidence.

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25
Q

Before the discovery of the electron, what were atoms thought to be?

A

Tiny spheres that could not be divided.

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26
Q

What happened to our knowledge of the atom in 1897?

A

JJ Thompson’s discovery of the electron led to the plum pudding model of the atom. The plum pudding model suggested that the atom is a ball ofpositive charge with negative electrons embedded in it.

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27
Q

What happened to our knowledge of the atom in 1909?

A

Ernest Rutherford’s results from the alpha particle 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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28
Q

What was our understanding of the nuclear model of the atom?

A

There was a tiny positively charged nucleus at the centre, where most of the mass is concentrated. A ‘cloud’ of negative electrons surrounds this nucleus. Most of the atom is empty space.

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29
Q

What was our understanding of the atom after the nuclear model?

A

Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus at specific distances. The theoretical calculations of Bohr agreed with experimental observations.

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30
Q

Why did the Bohr model make more sense than the nuclear model?

A

If the nuclear model were true, the atom would collapse into itself. Bohr suggested the electrons weren’t in a cloud but contained in shells at fixed distances from the nucleus.

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31
Q

What did experiments after the Bohr model find?

A

Later experiments led to the idea that the positive charge of any
nucleus could be subdivided into a whole number of smaller particles, each particle having the same amount of positive charge. The name proton was given to these particles.

32
Q

What was the final stage in our understanding of the atom?

A

The experimental work of James Chadwick provided the evidence
to show the existence of neutrons within the nucleus. This was
about 20 years after the nucleus became an accepted scientific
idea.

33
Q

Why did the new evidence from the scattering experiment lead to a change in the atomic model?

A

The results from the experiment did not match with the hypothesis As in, a few alpha particles were deflected back by the gold sheet instead of passing straight through so the positive charge of each atom could not have been very spread out.

34
Q

What is the radios of an atom?

A

0.1nm

35
Q

What is the radius of a nucleus?

A

1/10,000 that of an atom.

36
Q

What are isotopes?

A

Atoms with the same number of protons but a different number of neutrons.

37
Q

How are elements arranged in the periodic table?

A

The elements in the periodic table are arranged in order of atomic
(proton) number.

38
Q

Why is the periodic table arranged in this way?

A

So elements with similar properties are in columns, known as groups.

39
Q

Why is it called a periodic table?

A

Similar properties occur at regular intervals.

40
Q

What does it mean for elements to be in the same group?

A

Elements in the same group in the periodic table have the same
number of electrons in their outer shell (outer electrons) and this
gives them similar chemical properties.

41
Q

What does each new period represent in the periodic table?

A

Another full shell of electrons.

42
Q

How did scientists originaly order elements ?

A

Before the discovery of protons, neutrons and electrons, scientists
attempted to classify the elements by arranging them in order of
their atomic weights.

43
Q

What was wrong with the early periodic table?

A

The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.

44
Q

What did Mendeleev do the early periodic table?

A

Mendeleev overcame some of the problems by leaving gaps for
elements that he thought had not been discovered and in some
places changed the order based on atomic weights.

45
Q

How did Mendeleev originally order the elements?

A

He first ordered the elements in their atomic weight but switched that order if properties meant it should be changed.

46
Q

What did Mendeleev do second to his periodic table?

A

Gaps were left to make sure elements with similar properties stayed in the same groups.

47
Q

How did we adapt Mendeleev’s periodic table?

A

Elements with properties predicted by Mendeleev were discovered
and filled the gaps.

48
Q

How did the discovery of isotopes explain why the order based on atomic weights was not always
correct?

A

Isotopes of the same element have different masses but have the same chemical properties so occupy the same position on the periodic table. So their properties should be taken into account also.

49
Q

What makes an element a metal?

A

They react to form positive ions.

50
Q

What makes an element a non-metal?

A

They react to form negative ions.

51
Q

Where are metals found in the periodic table?

A

Metals are found to the left
and towards the bottom of the periodic table.

52
Q

Where are non-metals found on the periodic table?

A

Non-metals are found
towards the right and top of the periodic table.

53
Q

Physical properties of metals?

A

They’re strong, but are also malleable. They’re great at conducting electricity and heat. They have high boiling and melting points.

54
Q

Physical properties of non metals.

A

They are dull looking, brttle, aren’t always solid at room temperature, generally don’t conduct electricity, lower density.

55
Q

Properties of transitional metals?

A

Can have more than one ion. Are often coloured. Make good catalysts.

56
Q

What are group 0 elements also known as?

A

Noble gases

57
Q

Why are group 0 elements unreactive?

A

They are inert and do not easily form molecules because their atoms have stable arrangements of electrons.

58
Q

Properties of noble gases.

A

Colourless, monatomic gases, non-flammable.

59
Q

Patterns in the properties of noble gases.

A

The boiling points of the noble gases increase as you move down the group. This 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. This requires more heat energy.

60
Q

What are elements of group 1 also known as?

A

Alkali metals

61
Q

How many electrons do group1 elements have on their outer shell?

A

1.

62
Q

Properties of group 1 elements?

A

Soft, low density, very reactive.

63
Q

Patterns in the properties of group 1 elements going down the group.

A

The reactivity increases due to the outer electron becoming more easily lost as the attraction between the nucleus and electron decreases, because the electron is furher away from the nucleus. Lower melting and boiling points, higher relative atomic mass.

64
Q

What compouds so alkali metals form with non-metals?

A

Ionic compounds.

65
Q

What happens when group 1 elements react with water?

A

They react vigorously to produce hydrogen gas and metal hydroxides. 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.

66
Q

What happens when group 1 elements 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 reaction gets more vigorous.

67
Q

What happens when group 1 metals react with oxygen?

A

They form a metal oxide. Lithium reacts to form lithium oxide. Sodium reacts to form a mixture of sodium oxide or and sodium peroxide. Potassium reacts to form a mixture of potassium peroxide and potassium superoxide.

68
Q

What are group 7 elements known as?

A

Halogens.

69
Q

What type of molecules are halogens?

A

Diatomic molecules.

70
Q

What is fluoride like?

A

Very reactive poisonous yellow gas.

71
Q

What is chlorine like?

A

fairly reactive, poisonous dense green gas.

72
Q

What is bromine like?

A

dense, poisonous, red-brown volatile liquid.

73
Q

What is iodine like?

A

dark grey crystalline solid or purple vapour.

74
Q

Patterns going down group 7.

A

In Group 7, the further down the group an element is the higher its
relative molecular mass, melting point and boiling point.
In Group 7, the reactivity of the elements decreases going down the group. It’s harder to gain an electron because the outer shell’s further from the nucleus.

75
Q

What happens when halogens react with non-metals?

A

They share an electron via covalent bonding and form a simple molecular structure.

76
Q

What happens when halogens react with metals?

A

They form -1 ions called halides as they lose an electron. They have ionic structures.

77
Q

What is displacement like in halogens?

A

A more reactive halogen will displace a less reactive halogen in a reaction from an aqueous solution of its salt. . For example Chlorine can displace bromine and iodine in a reaction.

Chemistry (9 decks)

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