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Chemistry > C4 > Flashcards

C4 Flashcards

1
Q

What are the group 1 elements also known as?

A

Alkali metals

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2
Q

Why are the elements in group 1 called alkali metals?

A

They react with water to form alkaline solutions

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3
Q

What are the typical properties of the group 1 elements?

A

They are shiny when freshly cut
Good conductors of electricity

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4
Q

What state of matter are the group 1 elements at room temp and what is odd about that?

A

They are all solid at room temp but are soft enough to cut with a knife

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5
Q

Why are the group 1 metals only shiny when freshly cut?

A

They oxidise with air and lose their shiny colour

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6
Q

What is the trend as you go down group 1?

A

Density increases (sodium is more dense than expected)
Melting point decreases
They get softer
The reactivity increases

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7
Q

What do the alkali metals react with water to produce?

A

Metal hydroxide and hydrogen

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8
Q

What is the general half equation for group 1?

A

M = the symbol of the element

M = M^+ + E^-
M = M plus (plus) e minus

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9
Q

How do the first 3 element of group 1 react?

A

Lithium - fizzes steadily and slowly disappears
Sodium - melts to form a silvery ball, fizzes vigorously, quickly disappears
Potassium - immediately ignites, burns with a lilac flame, very quickly disappears

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10
Q

Why does the reactivity of group 1 increase as you go down?

A

Because it becomes easier to lose their outer electrons as the electrons get further and further away from the nucleus

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11
Q

Why does the density increase as you go down group 1?

A

The atom gets bigger (mass increases) due to the increase of electron shells

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12
Q

Why does the melting point decrease as you go down group 1?

A

The forces of attraction decrease as you go down the group

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13
Q

What is fluorine at room temp?

A

A pale yellow gas

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14
Q

What is chlorine at room temp?

A

A green gas

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15
Q

What is bromine at room temp?

A

An orange-brown liquid that vaporises easily

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16
Q

What is iodine at room temp?

A

A shiny grey-black crystalline solid that sublimes to form a purple vapour

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17
Q

What are the physical properties of the elements in group 7?

A

They are brittle when solid and are poor conductors of electricity

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18
Q

What do group 7 elements exist as?

A

Diatomic molecules

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19
Q

What are the group 7 elements known as?

A

The halogens

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20
Q

What is the trend as you go down group 7?

A

The density increases
The melting and boiling points increase
The reactivity decreases

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21
Q

Why are the group 7 elements called halogens?

A

They react with metals to produce salts
They react vigorously with the alkali metals especially if the metal is heated first

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22
Q

What is the half equation for the halogens?

A

X is the symbol of a halogen
X (lower) 2 + 2e- —> 2X-
X lower 2 + 2e minus goes to 2x minus

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23
Q

Why does the reactivity of the halogens decrease as you go down the group?

A

It becomes more difficult to gain an electron due to the higher energy level

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24
Q

Why does the melting and boiling point increase as you go down group 7?

A

The atoms increase in size as they gain extra electron shells and the intermolecular forces become stronger

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25
Why does the density increase as you god own group 7?
The molecules get larger due to the extra electron shells
26
What happens in a halogen displacement reaction?
A halogen will displace a less reactive halogen from its halide ions
27
What would happen if the halogens tried to displace each other?
Chlorine displaces bromine from bromides Bromine would displace iodine from iodides Iodine cannot displace anything
28
How can you prove the order of reactivity of the halogens?
Use halogen displacement reactions
29
What type of reaction is a halogen displacement reaction?
A redox reaction
30
What is a redox reaction?
A reaction in which oxidation and reduction both take place
31
Why are the element of group 0 called noble gases?
They are so unreactive
32
What are all the elements of group 0 like at room temp?
They are all gases at room temp
33
Why are the noble gases so unreactive?
They have complete electron shells so that have no tendency to lose or gain electrons to form ions.
34
What word describes the noble gases?
Monatomic
35
What is the trend as you go down group 0?
The attractive forces between atoms get stronger The boiling point increases The densities increase
36
Why does the boiling point increase as you go down group 0?
The atoms get bigger meaning the forces of attraction become stronger
37
What are the typical properties of the transition metals?
Shiny when freshly cut Good conductors if electricity Malleable
38
What are the properties of the transition metals compared to the alkali metals of group 1?
Stronger and harder Higher densities Have higher melting points (except for mercury) Less reaction
39
How do the transition metals react?
Slowly
40
How does iron react with water and oxygen?
To produce rust - hydrated iron(III) oxide
41
How do gold, platinum and iridium react with water and oxygen?
They don’t react at all
42
What is different about the transitions metals compared to the alkali metal?
Transition metals can form more than 1 type of ion - the Roman numbers in brackets shows the charge
43
What do metals form in reactions?
Positive ions
44
How would you know how reactive a metal is during a reaction?
The more easily metals form ions, the more reactive the metal is
45
How do you know if a metal can react with water or dilute acids?
If they are more reactive than hydrogen
46
What is the descending reactivity series of metals (with hydrogen)?
Potassium Sodium Calcium Magnesium Aluminium Zinc Iron Tin Lead (Hydrogen) Copper Silver Gold Platinum
47
What do the electrons on the right of a half equation mean for metals mean?
Oxidation
48
What do the electrons on the right of a half equation mean for metals mean?
Reduction
49
What are the patterns of reactivity in the periodic table?
Group 0 don’t react Reactive non-metals form covalent compounds with each other Metals can form ionic compounds with non-metals Group 1 and 2 metals are more reactive than other metals Non-metals in group 7 become less reactive down the group
50
How do you test for carbon dioxide?
Limewater (calcium hydroxide) turns cloudy when carbon dioxide is present (calcium carbonate produced)
51
How do you test for chlorine?
1. Dampen a piece of blue litmus paper 2. Hold the paper near to a container that holds the substance 3. Chlorine presence = paper turns red then white
52
How do you test for hydrogen?
Squeaky pop test Put a lighted splint near the container of gas Hydrogen presence = ignite with squeaky pop
53
How do you test for oxygen?
Put a glowing splint (lighted splint that has just been put out) Oxygen presence = splint relights
54
What happens during a flame test?
Heated metal ions = energy transferred to electrons Electrons move to higher electron shells When moved back, energy is transferred to surroundings as radiation - light
55
What colour does a lithium ion make in a flame test?
Red
56
What colour does a sodium ion make in a flame test?
Yellow
57
What colour does a potassium ion make in a flame test?
Orange-red
58
What colour does a copper ion make in a flame test?
Green-blue
59
What does a hydroxide test formula look like?
(Metal)SO4 + 2NaOH —> Cu(OH)2 + Na2SO4
60
What colour is iron(II) hydroxide precipitate?
Green
61
What does a word equation of a hydroxide precipitate test look like?
(Metal) Sulfate + Sodium Hydroxide —> (metal) hydroxide + sodium sulfate
62
Why is sodium hydroxide used in a hydroxide precipitate test?
It is insoluble
63
What colour is iron(III) hydroxide precipitate?
Orange-brown
64
What colour is copper(II) hydroxide precipitate?
Blue
65
What colour is calcium hydroxide precipitate?
White
66
What colour is zinc hydroxide precipitate?
White
67
How do you tell the difference between calcium hydroxide and zinc hydroxide?
Add excess sodium hydroxide solution Zinc hydroxide dissolves to a colourless solution Calcium hydroxide doesn’t dissolve
68
How do you test for sulfate ions?
Add a few drops of dilute hydrochloric acid Add a few drops of barium chloride solution (BaCl2) Sulfate ions presence = white precipitate
69
How do you test for carbonate ions?
Add dilute hydrochloric acid Carbonate ion presence = bubbles of gas produced Carbon dioxide confirmation = limewater test
70
Why is adding dilute hydrochloric acid a good test for carbonate ions?
Because it works whether the carbonate is insoluble or not
71
How do you detect the presence of halide ions?
Add a few drops of DILUTE nitric acid Then add a few drops of silver nitrate solution (AgNO3) Halide ions presence = precipitate formed
72
What colour precipitate do chloride ions make?
White
73
What colour precipitate do bromide ions make?
Cream
74
What colour precipitate do iodide ions make?
Yellow
75
What are instrumental methods of analysis?
When you use machine to carry out the analysis of a substance
76
What are the advantages of using instrumental methods of analysis?
Sensitivity - small substances Accuracy Speed - very fast
77
What does a peak represent in a gas chromatogram?
A substance present in the mixture
78
What do the areas under the peak mean in a gas chromatogram?
The relative amount of each substance in the mixture
79
What is the retention time in a gas chromatogram?
The time taken for a substance to travel through the chromatography column
80
What is a mass spectrometer?
A machine that can measure the masses of atoms and molecules
81
What is a mass spectrometer used to analyse?
The relative amounts of different isotopes of an element and the structure of molecules
82
Give an example of a field of science where a mass spectrometer is used and why?
Environmental science to detect toxic substances
83
How does a mass spectrometer analyse molecules?
The sample molecules are ionised by the machine to form molecular ions. These break up to form fragments which the machine can separate and detect
84
What does each peak in the mass spectrum represent?
A fragment of the molecule
85
What does the peak on the far right represent in a mass spectrum?
The molecular ion
86
What is the mass to charge ratio of the molecular ion peak equal to?
The relative formula mass of the molecule
87
What can’t a simple flame test be used to identify two ions present in a mixture?
The samples might produce two very similar colours and one of the colours might be masked
88
Why is Nichrome wire used in a flame test?
It doesn’t react or emit a colour
89
How do we ensure that the Nichrome wire is clean before usage in a flame test?
Dip it into hydrochloric acid and hold it in the flame until no colour is seen
90
How do you remove impurities when testing for sulfates?
You add dilute hydrochloric acid to get rid of carbonates and sulfites - they also make white precipitates with barium
91
What do we add to remove impurities when testing for halide?
Dilute nitric acid
92
What are halides?
Chemical compounds that contain halogen ions bonded to another ion.

Chemistry (8 decks)

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