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GCSE Chemistry > C2 > Flashcards

C2 Flashcards

1
Q

At what rate were chemists discovering element during the 19th century ?

A

Rapidly . Finding them every year

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2
Q

What was the goal of chemists during the 19th century for the periodic table?

A

Trying to find pattern in the behaviour of elements which would allow them to be ordered

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3
Q

What did John dalton do about the periodic table?

A

Arranged elements in order of their atomic weight. He was on of the first suggestions. In 1808 he published his table of elements

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4
Q

How did John Newlands build on Daltons ideas in 1864?

A

Realised every 8th element had similar properties. Released ‘law of octaves’, which assumes all elements had been found. His pattern broke down

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5
Q

How are elements in the periodic table arranged?

A

Atomic number ( number of protons) , so elements with similar properties are in ‘groups’.

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6
Q

Why the periodic table has its name?

A

Similar properties occur at regular intervals.

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7
Q

What is common about elements in the same group in terms of electronic structure?

A

Same number of electrons on the outer shell, this gives them similar chemical properties

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8
Q

What was the problem with the early periodic tables?

A

Incomplete and some elements were placed wrongly

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9
Q

Who was Mendeleev?

A

Russian chemist

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10
Q

What was mendeleevs breakthrough?

A

1869, ordered them in atomic weight, and with a periodic pattern so their properties could be seen

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11
Q

How many elements had been discovered by 1869?

A

50

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12
Q

What was the most important aspect of mendeleevs periodic table?

A

He left gaps for elements not yet discovered

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13
Q

What confirmed that mendeleevs periodic table was close to being correct?

A

Mendeleev predicted properties of elements to fit in spaces and years after his predictions matched reality.

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14
Q

What was the problem with mendeleevs periodic table?

A

Did not account for isotopes. Argon could not fit for example. Ordering by mass would put argon (noble gas) in the group 1 with the reactive metals

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15
Q

What change was made to mendeleevs periodic table during the 20th century?

A

Ordered it in terms of the elements proton number. The structural components of the element had been discovered now making this change easier. The table could now account for protons.

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16
Q

How was the periodic table measured before the discovery of protons, neutrons and electrons?

A

By mass of the atom (atomic weight)

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17
Q

How many groups are in the periodic table ?

A

8

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18
Q

What does the group number tell us about the electronic structure of the element?

A

The number of the group is the number of electrons on the valence shell.

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19
Q

How do metals and non metals react with electricity ?

A
  • metals conduct electricity

- non metals do not , they are an electrical insulator

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20
Q

What is the difference in boiling points , comparing metals and non metals ?

A

Metals usually have higher boiling and melting points .

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21
Q

What are physical properties of metals and non metals ?

A

Metals are ductile and malleable, non metals are brittle

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22
Q

Where are non metals found in the periodic table?

A

Top right , about the staircase

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23
Q

How do group ,5,6 and 7 elements react to form ions?

A

Gain electrons to form a negative ion . They then have the electronic structure of a noble gas.

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24
Q

Where are metals found in the periodic table ?

A

Left hand side and the centre.

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25
Q

How do group 1,2 and 3 elements react to form ions?

A

Lose electrons and form positive ions. They then have the same electronic structure as the noble gas.

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26
Q

How many electrons do noble gases have on their valence shell?

A

8 , a full valence shell

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27
Q

Features of a noble gas?

A
  • very stable
  • unreactive
  • exist as a single atom , they are a monatomic gas
  • do not form molecule as they have no tendency to react and modify their electronic structures
  • boiling points increase going down the group
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28
Q

What is the boiling point of the first and last element in group 8?

A
  1. Helium -269 degrees Celsius

6. Radon -62 degree celsius

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29
Q

What are transition metals?

A
  • block of metals in the middle of the periodic table. Not usually reactive , some like silver and gold are very unreactive.
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30
Q

Where are the alkali metals found?

A

First group on the left

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31
Q

What are the alkali metals ?

A

Lithium , sodium , potassium , rubidium , caesium and francium

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32
Q

How reactive are alkali metals?

A

Very reactive, have to be stored in oil to stop them from reacting with oxygen

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33
Q

What is the trend in terms of reactivity in group 1?

A

As you go down the group the elements become more reactive

34
Q

What elements are too reactive to be used in school?

A

Rubidium , caesium and francium. Francium is dangerously radioactive

35
Q

How dense are alkali metals?

A

Have a very low density’s . Sodium , lithium and potassium have density’s lower than 1g/cm^3 . Which means they float on water.

36
Q

How hard are alkali metals?

A

Soft , can be cut with a knife.

37
Q

How do alkali metals react with oxygen?

A

Silvery and shiny at first , but once its reacted with oxygen it goes dull and forms a layer of oxide on the shiny surface.

38
Q

What is the equations for the reaction between oxygen and sodium?

A

Sodium +oxygen —-> sodium oxide

39
Q

What happens if a hot alkali metal is put into a gas jar of oxygen?

A

Burns vigoursly forming a white smoke of their oxides

40
Q

What decides the properties of an element?

A

Electronic structure. Group 1 elements are unstable as they have only 1 valence shell electron

41
Q

What does an alkali metal need to do to gain stability?

A

Loose one electron, to get the stable state of a noble gas

42
Q

What happens if a group 1 metal reacts with a non metal?

A

Lose outer shell electron forming a metal carrying a 1+ charge eg. Na+ , k+ they always form an ionic compound

43
Q

What is the trend for group one metals boiling and melting points?

A

Go down the group the boiling and melting points get lower. Group 1 metals have low boiling points compared to other metals.

44
Q

How do lithium , sodium and potassium react with water?

A
  • float on water , moving around and fizzing

- fizzing happens because the metals react with water to form hydrogen gas

45
Q

What happens when potassium reacts with water?

A

It is so vigorous , the hydrogen gas ignites. It burns with a lilac flame

46
Q

What does a reaction between an alkali metal and water produce ?

A
  • metal hydroxide

- hydrogen gas

47
Q

What happens when the metal hydroxide is formed ?

A

It is soluble in water. It leaves a colourless solution with a high ph .

48
Q

What is the equation for an alkali metal reacting with water?

A

Metal +water —-> metal hydroxide +hydrogen

49
Q

What other non metals do group 1 gases react vigorously with?

A

Chlorine gas

50
Q

What does a reaction between a metal and chlorine gas produce?

A

Metal chloride. Which is a white solid

51
Q

What happens to the metal chloride once it is formed ?

A

Dissolves into water to form a colourless solution.

52
Q

What is the trend going down group 1 for the reaction with chlorine gas?

A

The reaction gets more and more vigorous, as it becomes easier to lose the single electron on the valence shell, forming a 1+ ion.

53
Q

What is the equation for the reaction between sodium and chlorine gas ?

A

Sodium + chlorine —–> sodium chloride

54
Q

What are group 7 halogens?

A

Group of toxic non metals that have coloured vapours. They have fairly typical properties of non metals.

55
Q

What are the trends for the boiling and melting point of group 7 halogens?

A

Increase going down the group . Relatively low

56
Q

What sort of conductors are group 7 halogens?

A

Poor conductors of heat and electricity

57
Q

How many electrons do group 7 halogens have on their valence shells?

A

7

58
Q

What does the electronic structure determine for the halogen?

A

How it reacts

59
Q

What does the halogen need to do to become a noble gas?

A

Gain an extra electron

60
Q

What happens if a halogen reacts with a non metal ?

A

Gain an extra electron by sharing pairs of electrons with another atom.

61
Q

What is the trend of reactivity in group 7 halogens?

A

Less reactive going down the group

62
Q

What happens when halogens react with metals?

A

Gains an electron , forming a 1- charge

63
Q

What is the rule for displacement reactions between halogens?

A

More reactive halogen will displace a less reactive halogen from solutions of its salt .

64
Q

What happens when chlorine dissolved in water mixes with potassium bromide solution?

A

Colour of solution is due to less reactive of pair of halogens which is left in the solution as the aqueous molecule.

65
Q

What colour is chlorine , bromine and iodine when they react with a non metal?

A

Chlorine=green
Bromine=yellow
Iodine=red / brown

66
Q

Chlorine + potassium bromide is equal to what?

A

Potassium chloride +bromine

67
Q

What halogen displaces all of them?

A

Fluorine

68
Q

What is the trend in group 1 metals In terms of reactivity ?

A

Gets higher going down the group

69
Q

What is the trend of reactivity for group 7 halogens?

A

Less reactive going down the group

70
Q

What explains the trends in elements?

A

Electronic structure

71
Q

What happens as you go down a group in the periodic table?

A
  • Increases the shells

- atoms get larger

72
Q

What is the rule for displacement reactions between halogens?

A

A more reactive halogen will displace a less reactive halogen from a solution of its salt.

73
Q

What halogen displaces all other halogens?

A

Fluorine

74
Q

What happens to large atoms electronic structure?

A
  • lose electrons more easily , going down the group

- gain electrons less easily going down the group

75
Q

What are the reasons for larger atoms having those particular features?

A

Valence electrons are further away from the nucleus and its attractive forces
The inner shells screen or shield out electrons from the positive charge of the nucleus

76
Q

What happens to alkali metals when forming chemical bonds?

A

Lose electrons

77
Q

What happens to halogens when forming chemical bonds?

A

Gain electrons

78
Q

Why does reactivity increase going down group 1?

A

Atoms get larger so the single electron in the valence shell is attracted less strongly to the positive nucleus . Electrostatic attraction with the nucleus gets weaker because the distance between the valence electron and nucleus increases.

79
Q

What do the shells do to the electrostatic forces between the nucleus and valence shell?

A

Weaken them

80
Q

What does the amount of protons in the nucleus mean?

A

A greater attraction

81
Q

Does going down the group lead to a greater attraction between protons and valence electrons in group 1?

A

No , there is a shielding effect by the shells that outweighs the increased positive charge

82
Q

Why does reactivity decrease going down group 7?

A
  • size of the atom
  • shielding affect of inner electrons
  • nuclear charge

GCSE Chemistry (14 decks)

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