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A - Chemistry GCSE > LAST MIN- do deck 1 tho > Flashcards

LAST MIN- do deck 1 tho Flashcards

1
Q

Names some physical properties of Alkali metals

A

Very soft so can be cut with a knife

Low melting points

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2
Q

What kind of compounds do group 1 form? and Why?

A

Ionic compounds because they lose their outer shell electron very easily

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3
Q

What happens when lithium sodium and potassium react with water

A

Produces a metal hydroxide and hydrogen gas

fizzes and bubbles in the water

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4
Q

Why does potassium ignite when reacting with water??

A

Because it gets hot enough to ignite the hydrogen gas being produced

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5
Q

What is the balanced symbol equation for Alkali metal reacting with water (for sodium)

A

2Na + 2H2O&raquo_space;» 2NaOH + H2

-Works for all group 1

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6
Q

What is the half equation for lithium forming a 1+ ion in an ionic compound

A

Li&raquo_space;»> Li+ + e-

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7
Q

How does reactivity change as you go down group 7

A

decreases as its harder to attract an extra electron as its outer shell is too far from the nucleus

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8
Q

What is the appearance and state of chlorine, bromine, and iodine at room temperature

A

Chlorine - fairly reactive, poisonous green gas
Bromine- poisonous brown liquid which gives off orange vapour
Iodine- dark grey crystal solid which gives off purple vapour when heated

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9
Q

How do boiling and melting points change as you go down group 7

A

It increases as they become solids as you go down so more energy is needed to break bonds

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10
Q

What do halogens make when reacting with hydrogen

and example

A

Hydrogen halides which are soluble in water to form acidic solutions
eg) Hydrochloric acid

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11
Q

What is the balanced equation for the formation of a common hydrogen halide

A

H2 + Cl2&raquo_space;»» 2HCl

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12
Q

What do halogens make when reacting with a metal

A

They react vigorusly to make a metal halide which is often with group 1 eg) sodium chloide
- Halogens higher up on the group react easier as they attract an outer shell electron more easily

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13
Q

What is a balanced equation for the formation of a metal halide (sodium chloride)

A

2Na + Cl2&raquo_space;»> 2NaCl

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14
Q

What is a chemical property of a hydrogen halide

A

Soluble in water

HCl is aqueous

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15
Q

Why is a displacement reaction a redox reaction

A

Because the halogens are reduced and gain electrons whilst halide ions are oxidised and lose electrons

Halide ion = The salt solution
Halogen = is the halogen being addedq

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16
Q

What is the ionic equation for chlorine displacing

bromine

A

Cl2 + 2Br-&raquo_space;»> Br2 + 2Cl-

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17
Q

How could you show the reactivity trends of halogens

A

add halide salt solution to test tube and add halogen

and if colour change then displacement reaction has occurred.

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18
Q

Name some properties of group 0

A

Colourless gases at room temperature
Monotomic - single atoms not molecules
Non-flammable

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19
Q

what is the trend for boiling and melting points going down group 0

A

increases

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20
Q

what is the trend for density going down group 0

A

increases

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21
Q

What were daltons ideas about how atoms have changed?

A

Dalton described atoms as solid spheres made up of different elements
JJ Thomson said they werent solid spheres but were positively charged “pudding” with electrons inside the dough (plum pudding)
Rutherford conducted gold foil experiment showed PPmodel was wrong as some of the alpha particle beam bounced back showing there was a positively charged nucleus but some passed through showing empty space
Bohr model is close to current model but shows electrons in circular shells with a nucleus in the middle

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22
Q

How do you find the Ar of an element with many isotopes such as chlorine?

A

You would take an average of the mass numbers of each so 35.5

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23
Q

How did mendeleev arrange the periodic table?

A

Put them into groups based off their chemical properties and put them into columns
then periods across
when putting in order of atomic mass a pattern appeared. however a few didnt fit and not all had been discovered so he left gaps.

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24
Q

What is the modern periodic table like compared

A

We now have more knowledge of isotopes and know many more elements which still fit in order of atomic number. rows are called periods and each new one represents a new shell of electons.

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25
describe the general rule of how you would show if an atom had lost 2 electrons (with iron)
Fe2+ | this means it has two more protons than electrons giving it a positive charge.
26
Which groups are most likely to form ions
``` 1 &; 2 and 6 &; 7 group 1 make 1+ group 2 make 2+ group 6 make 2- group 7 make 1- ```
27
What is the difference between an atom and an ion
An ion is a charged particle
28
How are cations and anions formed
cations (positive) form when atoms lose electrons so they have more protons than electrons anions (negative) form when an atom gains electrons so there are more electrons than protons
29
What is the structure of an ionic compound
Giant ionic lattices, regular lattice with strong electrostatic forces of attraction
30
Name some properties of ionic compounds
High melting and boiling points due to strong electrostatic forces of attraction dont conduct because ions cant move in fixed positions dissolve easily in water as ions separate an move freely in solution.
31
Name some properties of covalent molecules
very strong covalent bonds forces of attraction are very weak low melting and boiling points because of this so most are liquids/ gas at room temp dont conduct as no free ions or electrons no rule of solubility
32
Give examples of allotropes of carbon
diamond, graphine, graphite, fullerines
33
What are some basic similarities / differences of simple covalent and giant covalent structures?
Giant have very high boiling and melting points as lots of energy is needed to break the strong covalent bonds dont conduct as no charged particles apart from graphene and graphite both are insoluble
34
Describe fullerines and their uses
hollow tubes of carbon in pentagons or hexagons can cage other molecules which is why theyre used to transport drugs. large surface area so good catalysts in industrial nanotubes have high tensile strength so used in sports equipment
35
How are the particles arranged in metals as well as properties
-giant structure, regular structure -outershell electrons are delocalised so carry current -metallic bonding have strong electrostatic forces of attraction between them so high melting and boiling points (apart from mercury) -dense malleable
36
(ions) Ammonium chemical formula
NH4+
37
(ions) Nitrate
NO3-
38
Sulfate ions
SO4 2-
39
Carbonate ions
CO3 2-
40
What is the law of conservation in a non- enclosed system
mass before doesnt equal mass after because some gas produced in the reaction could have escaped or oxygen from the air has reacted with the metal for example
41
Why is crude oil a finite source
because it is made from plants and animals under high temperatures and will eventually run out
42
How is crude oil separated?
Fractional Distillation- - fractions of crude oil are separated in fractionating column by their different boiling and melting points - In the column there's a temperature gradient (cold at top) - longer hydrocarbons have higher boiling points like bitumen so they drain out at the bottom of the column where its hottest
43
What is the equation for a combustion reaction with a hydrocarbon
Hydrocarbon + oxygen >>> Carbon Dioxide and water C3H8 + 5O2 >>>>> 3CO2 + 4H2O
44
What is a homologus series
family of molecules which have the same general formula and share similar chemical properties
45
What does complete combustion of hydrocarbons produce
Carbon dioxide and water
46
How do some hydrocarbons produce sulfur dioxide in use?
When fossil fuels are burned they release mostly CO2 but can also release other harmful gases such as sulfur dioxide or nitrus oxides sulfur dioxide (SO2) comes from sulfur impurities in the fossil fuels
47
what are the names of some pollutants responisble for acid rain
sulfur dioxide mixing with clouds to make it dilute and fall as acid rain
48
Why are oxides of nitrogen produced when fuels are burning in engines
Nitrogen oxides are produced by a reaction between oxygen and nitrogen in the air caused by the energy released in combustion reactions eg) internal combustion engines in cars
49
What causes photochemical smog
Nitrogen oxides (a harmful pollutants)
50
Why would hydrogen be a good/ bad alternative and renewable fuel
+very clean +no collutants +efficient energy source - expensive - hydrogen gas has to be manufactured which costs - uses energy from another source which creates pollutants - hard to store (explosive) and not widely available
51
Define cracking
breaking down of longer less useful chains of hydrocarbons to make smaller more useful ones to fit demand
52
What happens in cracking in terms of alkanes and alkenes
turns long saturated alkane molecules into smaller more useful unsaturated alkenes and alkane molecules
53
What is thermal decomposition
one substance breaks down into new ones when heated
54
What is the process of cracking
- vaporised hydrocarbons are passed over powdered catalyst at 400-700 degrees at 70 atmospheres - An aluminium oxide catalyst is used - long chain molecules "crack" on surface of catalyst
55
How was the Earths early atmoshere formed | Phase 1
- The earths surface cooled and a thin crust formed - volcanos kept erupting and releasing gases - degassing produced CO2 (also steam, methane, amonnia) - Then when it settled the earths atmosphere was mainly CO2 and water vapour and not much oxygen - this water vapour condensed to form oceans
56
How did the formation of oceans influence the composition of the atmosphere (phase 2)
- the oceans dissolved the CO2 | - nitrogen gas was put into the atmosphere by ammonia reacting with oxygen and released by denitrifying bacteria
57
Why did levels of Nitrogen increase (phase 2)
Because N2 isnt very reactive and amount increased because it isnt broken down
58
Why did photosynthetic organisms change the composition of the earths atmosphere (phase 2)
When green plants evolved, they removed CO2 and produced O2
59
Where did most of the CO2 end up (phase 2)
locked up in sedimentary rocks and fossil fuels
60
What did the build up of oxygen in the atmosphere lead to? (phase 3)
killed off organisms that couldnt tolerate it and allowed the evolution of more complex organisms that used oxygen
61
What does the ozone layer (O3) do? (phase 3)
blocked harmful rays from the sun so more complex organisms could evolve
62
What is the greenhouse effect
- The earth radiates heat as IR radiation - IR is absorbed by greenhouse gases - Some of the earths radiation is reflected back to earth by greenhouse gases and some is re-emitted into space - absorbtion and reflection which keeps the earth warm
63
What happens when the concentration of greenhouse gases increases
it leads to the enhance greenhouse effect where less radiation is re-emitted to space and short wave radition from the sun is absorbed in heating our atmosphere
64
Why historical data of recording temperature and CO2 levels less accurate
- because its taken in fewer location in the world unlike now its taken all over the world - and going back more there is no data for CO2 levels which means we dont have enough data to prove global warmng is caused by CO2
65
whats a functional group
group of atoms that determine how a molecule reacts. members of a homologus series conatain the same functional group
66
What is an addition reaction
Opening up the double bond of an alkene (unsaturated monomer) to make polymer chains eg) polyethene This is called addition polymerisation
67
How can you test for an alkene and why does this not work with alkanes
Bromine water- when shaken, addition reaction takes place where bromine is added across double bond Alkanes cant because they dont have a double bond.
68
What is the general formula of an alkane
CnH2n+2
69
What is the general formula of an alkene
CnH2n
70
What is the name and formula of the alcohol found in alcoholic drinks
Ethanol | 2C2H5OH
71
How are alcoholic drinks made from carbohydrates
They come from glucose a common sugar source which is mixed with yeast and fermented simple sugars like glucose are carbohydrates
72
What is the balanced equation for the formation of ethanol from carbohydrates
C6H12O6 >>>(yeast)>>> 2C2H5OH + 2CO2
73
Describe the fermentation process
- mix yeast and carbohydrates and leave in warm place - this is between 30-40 degrees for enzymes to work as fastest rate with denaturing - no oxygen should get to mixture so it respires anaerobically so ethanol becomes ethanoic acid - when concentration of alcohol reaches 10% reaction stops and yeast is killed off - collect ethanol from the top as yeast at bottom - can then be distilled to produce more concentrated alcohol
74
What is the general formula for an alcohol
CnH2n+1
75
what is the functional group of all alcohols
-OH group (attached on end of carbon chain)
76
What is a common chemical reaction of alcohols
an oxidation reaction using an oxidising reagent to form a carboxylic acid -It forms a double bond
77
What are some properties of alcohols
- soluble - flammable - higher boiling points than other hydrocarbons
78
What are the names of the first 4 carboxylic acids
Methanoic acid, ethanoic acid, propanoic acid, butanoic acid
79
What is the genral formula of a carboxylic acid
Cn-1H2n-1COOH eg) methanoic acid is just HCOOH ethanoic acid is CH3COOH
80
How are carboxylic acids formed?
-by the oxidation of alcohols (loss of electrons) -forms a double bond between carbon and oxygen - and -OH is attached to a carbon
81
what are the chemical properties of some carboxylic acids
- boiling point increases as molecules get bigger | - soluble
82
How do ethene molecules join together to form polyethene
- unsaturated ethene monomer opens up its double bond to join to other monomers - this creates a polymer chain in process of addition polymerisation
83
What is high density polyethene used for + | what about low density
- water pipes | - plastic bags
84
describe how polyesters are formed
-condensation polymerisation reaction - dicarboxylic acid and diol monomer react from their two functional groups -COOH and -OH - an ester link is formed between - for each ester link a molecule of water is lost
85
What is the starting material for most synthetic polymers
crude oil - a finite resource used to make plastics
86
What does adding sodium hydroxide to ammonium ions produce | how do we test for this
ammonia damp red litmus goes blue has distinct strong smell can be toxic
87
What is flame photometry
an instrumental method which allows you to idntify ions in a dilute solution by showing a unique line spectrum
88
What colours form is silver halide precipitates
Chloride - white Bromide - cream Iodide - yellow

A - Chemistry GCSE (11 decks)

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