Topic 1 - Atomic Structure and the Periodic Table Flashcards

1
Q

Alkali metals

A

The elements in Group 1 of the periodic table.

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2
Q

Atom

A

The smallest part of an element that can exist. All substances are made up of atoms.

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3
Q

Atomic nucleus

A

Positively charged object composed of protons and neutrons at the centre of every atom with one or more electrons orbiting it.

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4
Q

Atomic number

A

The number of protons in the nucleus.

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5
Q

Chromatography

A

A separation technique used to separate a mixture of chemicals by
distributing the components between two phases.

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6
Q

Compound

A

A substance made up of two or more types of atoms chemically combined together.

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7
Q

Crystallisation

A

A separation technique used to produce solid crystals from a solution by evaporating the solvent.

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8
Q

Displacement

A

A chemical reaction in which a more reactive element displaces a less reactive element from its compound.

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9
Q

Electron

A

Negatively charged subatomic particle which orbit the nucleus at various energy levels. Very small relative mass (negligible).

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10
Q

Electron shell

A

Different energy levels in atoms occupied by electrons.

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11
Q

Element

A

A substance made up of only one type of atom.

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12
Q

Filtration

A

​A separation technique used to separate solids from liquids.

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13
Q

Fractional distillation:

A

A method of separating a mixture of substances according to their different boiling points.

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14
Q

Group (periodic table)

A

The columns of the periodic table represent different groups of elements. Elements with similar properties are in the same group.

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15
Q

Halogens

A

The elements in Group 7 of the periodic table.

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16
Q

lon

A

An atom or molecule with an electric charge due to the loss or gain of electrons.

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17
Q

Isotope

A

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

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18
Q

Mass number:

A

The total number of protons and neutrons in the nucleus.

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19
Q

Metals

A

Elements that react to form positive ions. Found to the left and towards the bottom of the periodic table.

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20
Q

Mixture

A

A mixture consists of two or more elements or compounds not chemically combined together.

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21
Q

Neutron

A

Neutral subatomic particle present in the nucleus of the atom. Relative mass of 1.

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22
Q

Noble gases

A

The elements in Group 0 of the periodic table.

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23
Q

Non-metals

A

Elements that react to form negative ions. Found towards the right and top of the periodic table

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24
Q

Nuclear model

A

The nuclear atomic model stated that the mass was concentrated at the centre of the atom and that the nucleus was charged.

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25
Q

Periodic table

A

Table of elements arranged in order of atomic number and such that elements with similar properties are in the same column (group).

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26
Q

Plum pudding model

A

Atomic model devised after the discovery of the electron. The model suggests the atom is a ball of positive charge with negative electrons scattered through it.

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27
Q

Proton

A

Positively charged subatomic particle present in the nucleus of the atom. Relative mass of 1

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28
Q

Relative atomic mass

A

An average value that takes account of the abundance of the isotopes of the element.

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29
Q

Simple distillation

A

A procedure by which two liquids with different boiling points can be separated.

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30
Q

Transition metals

A

The collection of metallic elements in the middle of the periodic table.

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31
Q

How are the element listed and approximately how many are there?

A

They are listed in the periodic table; there are approximately 100.

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32
Q

Elements can be classified into two groups based on their properties; what are these groups?

A

Metals and non-metals

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33
Q

What are the methods through which mixtures can be separated (there are five)? Do these involve chemical reactions?

A

Filtration, crystallisation, simple distillation, fractional distillation and
chromatography; they do not involve chemical reactions

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34
Q

Describe and explain simple distillation.

A

Simple distillation is used to separate liquid from a solution - the liquid boils off and condenses in the condenser. The thermometer will read the boiling point of the pure liquid. Contrary to evaporation, we get to keep the liquid.

35
Q

Describe and explain crystallisation/evaporation

A

Evaporation is a technique for separation of a solid dissolved in a solvent from a solvent (e.g. salt from H,°).The solution is heated until all the solvent evaporates; the solids stays in the vessel.Crystallisation is similar, but we only remove some of the solvent by evaporation to form a saturated solution (the one where no more solid can be dissolved). Then, we cool down the solution. As we do it, the solid starts to crystallise, as it becomes less soluble at lower temperatures. The crystals can be collected and separated from the solvent via filtration.

36
Q

Describe and explain fractional distillation

A

Fractional distillation is a technique for separation of a mixture of liquids. It works when liquids have different boiling points. The apparatus is similar to the one of simple distillation apparatus, with the additional fractionating column placed on top of the heated flask. The fractionating column contains glass beads. It helps to separate the compounds. In industry, mixtures are repeatedly condensed and vapourised. The column is hot at the bottom and cold at the top. The liquids will condense at different heights of the column.

37
Q

Describe and explain filtration

A

Filtration is used to separate an insoluble solid is suspended in a liquid. The insoluble solid (called a residue) gets caught in the filter paper, because the particles are too big to fit through the holes in the paper. The filtrate is the substance that comes through the filter paper. Apparatus: filter paper + funnel.

38
Q

Describe and explain chromatography

A

Chromatography is used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place a piece of paper with a spot containing a mixture in a beaker with some solvent. The bottom of the paper has to be in contact with the solvent. The solvent level will slowly start to rise, thus separating the spot (mixture) into few spots (components).

39
Q

What is a separating funnel?

A

A separatory funnel is an apparatus for separating immiscible liquids.
Two immiscible liquids of different densities will form two distinct layers in the separatory funnel.
We can run off the bottom layer (the liquid with greater density) to a separate vessel.

40
Q

Describe the plum-pudding model

A

The atom is a ball of positive charge with negative electron embedded in it.

41
Q

Describe the Bohr/nuclear model and how it came about

A

The nuclear model suggests that electrons orbit the nucleus at specific distances (shells) - it came about from the alpha scattering experiments

42
Q

Later experiments led to the discovery of smaller, positive particles in the nucleus; what are these particles called?

A

Protons

43
Q

What did the work of James Chadwick provide evidence for?

A

The existence of neutrons in the nucleus

44
Q

Describe the structure of an atom

A

The atom has a small central nucleus (made up of protons and neutrons) around which there are electrons.

45
Q

Describe the properties of noble gases. Discuss the trends in properties down the group.

A

Non-metals, gases, low boiling points, unreactive (full outer shell; they don’t easily accept or lose electrons).
The boiling point increases down the group, as the atoms get heavier.

46
Q

State the colours of flames observed when lithium, sodium, and potassium burn in oxygen

A

Crimson-red, Li
Yellow-orange, Na
Lilac, K

47
Q

State three common characteristics of transition metals

A
  • Ions with different charges
  • Coloured compounds
  • Catalytic properties
48
Q

Compare group 1 metals with transition metals

A

Group 1 metals and transition metals are heat and electricity conductors. They are shiny when polished and form ionic compounds with non metals.
Transition metals have higher densities and higher melting points than Group 1 metals. They are less reactive and harder than Group 1 metals.

49
Q

A more reactive halogen displaces a less reactive one from an aqueous solution of its salt; explain the trend in reactivity of halogens in these reactions

A

Reactivity decreases down the group. As we go down the group, the atoms get larger, so an incoming electron will be less tightly held by the attractive forces from the nucleus. That’s why Cl, displaces Br and I.

50
Q

A more reactive halogen displaces a less reactive one from an aqueous solution of its salt; write the equations and state the colour change seen when chlorine reacts with sodium bromide and when chlorine/bromine reacts with sodium iodide.

A

Cl, + 2 NaBr -+ Br, + 2 NaCI, or Cl, + 2Br -+ Br, + 2 CF;
in this reaction, an orange colour of Br, would appear
CI, + 2 Nal -+ 1 + 2 NaCI, or Cl, + 21- -+ 1, + 2 CI Br, + 2 Nal -+ 1, + 2 NaBr, or Br, + 21- -+ I,+ 2 Br; in these two reactions, a brown colour of I, would appear

51
Q

State three changes that occur in Group 7 as one moves down the group

A
  • Higher relative molecular mass
  • Higher melting and boiling point
  • Less reactive - less easily gain electrons
52
Q

State five State Group 7 elements and states of matter of molecules they form

A
  • Fluorine, F. F, is a pale yellow gas.
  • Chlorine, CI. Cl, is a pale green gas.
  • Bromine, Br. Br, is dark brown liquid
  • lodine, I. I, is a grey solid.
53
Q

State five characteristics of Group 7

A
  • 7 electrons in outer shell
  • Coloured vapours
  • Diatomic molecules
  • Form ionic salts with metals
  • Form molecular compounds with non-metals
54
Q

How does reactivity change moving down Group 1? Why?

A

Reactivity increases as the atoms get larger and the distance between the nucleus and the outer electrons increases and thus attraction from the nucleus decreases, allowing them to more easily lose electrons.

55
Q

How do Group 1 elements react with water?

A

They release hydrogen and form hydroxides which dissolve to form alkaline solutions; react vigorously with water fizzing and moving around on the surface of the water.

56
Q

How do Group 1 elements react with non-metals? Why are these reactions similar for the different Group 1 elements?

A

They form ionic compounds which are soluble white solids which form colourless solutions - they all have one electron in their outer shell.

57
Q

State three characteristics of the Alkali Metals

A

All have one electron in their outer shell; have low density; are stored under oil (to prevent reactions with oxygen or water); are soft (can be cut with knife).

58
Q

Elements in Group 1 are known as…

A

The alkali metals

59
Q

Elements that do not form positive ions are…?

A

Non-metals

60
Q

Elements that react to form positive ions are…?

A

Metals

61
Q

The majority of elements are..

A

Metals

62
Q

Mendeleev overcame some problems with the table by doing what? He also changed the order of some elements based on what?

A

Leaving gaps; atomic weights

63
Q

Knowledge of what made it possible to explain why the order based on atomic weights was not always correct?

A

Isotopes

64
Q

Early periodic tables were incomplete and elements were placed in inappropriate groups if what was to be followed?

A

The strict order of atomic weights

65
Q

What change in shell number is seen as one moves down a group?

A

The number of shells increases

66
Q

In terms of shells, what is the difference between elements in the same period?

A

They have the same number of shells

67
Q

Elements in the same group have the same number of electrons in their outer shell; what does this tell us about their chemical properties?

A

They have similar chemical properties

68
Q

The elements of Group 0 are more commonly known as…?

A

The noble gases

69
Q

Electrons occupy particular energy levels, with each electron in an atom at a particular energy level; which available energy level do electrons ccupy?

A

The lowest available energy level

70
Q

In terms of energy levels, what are the differences between elements of the same period?

A

They have the same number of energy levels

71
Q

Are elements in the same group similar or different?

A

They may have similar chemical properties, as they have the same number of outer shell electrons.

72
Q

Explain the following: solute, solvent, solution, miscible, immiscible, soluble, insoluble.

A

A solute is a substance that is dissolved in a solvent. Together, they form a solution.
Miscible refers to the substances (particularly liquids) that mix together, e.g. water and alcohol. Water and oil are immiscible, i.e. they do not mix.
Soluble refers to the substance that can be dissolved in a solvent, e.g. salt in water. Insoluble substance won’t dissolve in a particular solvent.

73
Q

What is formed when a non-metal reacts with a non-metal?

A

A molecular compound containing covalently bonded atoms.
Atoms share electrons, as opposed to transferring electrons between each other (cf. ionic compounds).

74
Q

What is formed when a metal reacts with a non-metal?

A

An ionic compound (made of positive and negative ions).

75
Q

Metal properties

A

Boiling/meting point: High
Conductivity: Heat and electricity
Apperance: Shiny
Malleability: Yes
Density: High
Oxides: Basic

76
Q

Non-metal properties

A

Boiling/metal point: Low
Conductivity: Don’t conduct heat electricity
Apperance: Dull
Malleability: Brittle
Density: Low
Oxides: Acidic

77
Q

He, Be, F, Na, Ca electron configurations (respectively):

A

2
2.2
2,7
2,8,1
2,8,8,2

78
Q

Do isotopes of a certain element have the same chemical properties?

A

They have the same chemical properties as they have the same electronic structure

79
Q

How does one calculate the number of neutrons using mass number and atomic number?

A

Subtract the atomic number from the mass number

80
Q

Where is the majority of mass of an atom?

A

The nucleus

81
Q

What is the radius of a nucleus and what is it compared to that of the atom?

A

1 x 10-14 m and 1/10000

82
Q

What is the radius of an atom?

A

0.1 nm

83
Q

Explain why atoms are electrically neutral.

A

They have the same number of electrons and protons

84
Q

State the relative masses and relative charges of the proton, neutron and electron

A

Masses: 1, 1, very small ; Charges: 1, 0 , -1 (respectively)