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Chemistry Flashcards

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0
Q

What is the atomic number ?

A

Number of protons

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1
Q

What is the mass number ?

A

Total number of protons and neutrons

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2
Q

How do you get the number of neutrons ?

A

Subtract the atomic number from the mass number

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3
Q

What are compounds ?

A

Compounds are formed when atoms of two or more elements are chemically bonded.

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4
Q

Give an example of a chemical bond

A

Carbon dioxide

carbon and oxygen

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5
Q

What is an isotope ?

A

Isotopes are different atomic forms of the same element which have the same number of protons but a different number of neutrons.

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6
Q

Give an example of a isotope

A

Carbon 12 and carbon 14

Isotopes have same atomic number but different mass number.

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7
Q

What is ionic bonding

A

The transferring of electrons

- in ionic bonding atoms lose or gain electrons to from charged particles.

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8
Q

Why do atoms ionic bond ?

A

They bond so they have a full outer shell so they are stable and are similar to noble gases.

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9
Q

Which atoms/elements want to get rid of electrons ?

A

Sodium, potassium and calcium. Because they only have one or two electrons on their outer shell.

(All of the atoms on the left hand side of the periodic table )

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10
Q

Which atoms want to gain electrons ?

A

Oxygen and chlorine. - atoms on the other side of the periodic table e.g group 6 and 7.

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11
Q

What is the structure of ionic compounds ?

A

Ionic compounds always have giant ionic lattices. The ions are closely packed n a regular lattice arrangement.

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12
Q

What are the properties of ionic compounds ?

A

They have very strong electrostatic forces of attraction. Between oppositely charged ions.

They have high melting points and high boiling points, due to strong attraction between ions.

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13
Q

Can ionic compounds carry an electric current ?

A

Yes, but only when the ionic compound is melted as the ions are free to move and they’ll carry a electric current

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14
Q

Can ionic compounds dissolve ?

A

They can dissolve easily in water, as the ions are separate and are free to move in the solution, allowing a current to flow through it.

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15
Q

Which groups are most likely to form ions ?

A

Group 1 & 2 and 6 & 7 are most likely to form ions.

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16
Q

Ions have a electronic structure of a …..

A

Noble gas

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17
Q

Ionic bonding happens between a …..

A

Metal and a non metal

Group 1&2). (Group 6&7

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18
Q

What is the overall charge of any compound

for balancing equation

A

Zero

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19
Q

What is covalent bonding

A

Covalent bonding is the sharing of electrons with other atoms

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20
Q

In covalent bonding which shell of electrons is shared

A

The outer shell.

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21
Q

What are the two types of covalent substances

A

Simple molecular structure and giant covalent structures which are macromolecules.

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22
Q

What are the properties of simple covalent substances ( there are 4)

A
  • Very strong covalent bonds between molecules
  • Forces of attraction between molecules are week
  • feeble intermolecular forces make the boiling and melting point very low
  • molecular substances don’t conduct electricity heavies they have no ion which = no electrical charge.
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23
Q

Properties of giant covalent structure

A

( similar to ionic structure, but have no ions)

  • high boiling and melting point
  • do not conduct electricity even when molten ( except for graphite )

-

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24
Q

Example of giant covalent structure and their properties

A

Diamond - each atom has 4 covalent which are very rigid - hardest natural substance and attractive

Graphite - each atom has 3 covalent bonds

  • has layers that slide over each other - soft - weak intermolecular forces
  • only non-metal which can conduct electricity and heat as each carbon atom has delocalised electrons
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25
Q

What type of structures are metals ?

small lattice, giant structure, nano

A

Giant structure

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26
Q

What are the properties of metal/metal structures /metal bonds

A
  • free electrons/delocalised electrons
  • good conductors of heat and electricity
  • strong forces of electrostatic attraction between positive metal ions and negative electrons.
  • layers can slide over each other allowing metals to be bent
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27
Q

What is an alloy ?

A

An alloy is a mixture of two or more metals.

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28
Q

Properties of an alloy

A
  • they are harder than pure metals
  • when different metals are mixed they have different sized atoms leading to the structure becoming distorted which makes it more difficult for them to slide over each other.
  • so alloys are harder
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29
Q

Name a smart material, what it is used for and it’s properties

A

Nitinol - a shape memory alloy
- used for braces and glasses frames

  • it can be bent and twist - if bent too much it can stay that shape
  • it can be heated, for it to go back to its ‘remembered’ shape
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30
Q

What is a nano particle ?

A
  • really tiny particles 1-100 nm

- nm stands for nano metre

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31
Q

What do nano particles contain ?

A

They contain fullerenes - these are molecules of carbon - Arranged in hexagonal rings

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32
Q

Uses of nano particles

A
  • they have huge surface area to volume ratio which is useful for making industrial catalyst
  • nanotubes can be used to make stronger,lighter building material
  • nanotubes can conduct electricity and be used in circuits

Etc ( more in textbook )

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33
Q

What is relative atomic mass ?

A

Relative atomic mass = mass number = number of protons and neutrons

(relative atomic mass is the same as mass number)

34
Q

What is relative formula mass ?

A

All the relative atomic masses added together

E.g MgCl2

  • Mg = 24
  • Cl2 = 35.5 x 2 = 95

So relative formula mass of MgCl2 = 95

35
Q

What is a mole ?

A

A mole of a substance is equal to its relative formula mass in grams

36
Q

Formula for working out moles

A

Mass in grams (of element)
Number of moles = ——————————–
Relative formula mass (of element)

37
Q

Formula for calculating %mass of a a element in a compound

A

Relative atomic mass X number of atoms in elements
———————————————- X 100
Relative formula mass ( of whole compound )

38
Q

What is yield ?

A
  • The amount of product you get is known as yield

- The more reactants you start with the higher the actual yield

39
Q

What is the formula for percentage yield ?

A 
Actual yield (grams)
   -------------------------------  x 100
      Predicted yield (grams)
40
Q

Reasons why you can never get 100% yield

A
  • The reaction is reversible ( reaction will never be completed because reaction goes both way)
  • when you filter a liquid to remove solid particles, you may lose some liquid or solid
  • sometimes reactants can be used up randomly
41
Q

How can artificial colours be seperated

A

Using paper chromatography

42
Q

Method of paper chromatography

A
  1. Extract the colour from the food sample by placing it in a cup with solvent ( water or ethanol)
  2. Put spots of the colour on a PENCIL baseline
  3. Roll up sheet and put into beaker with solvent, keep baseline above solvent
  4. solvent seeps up the paper, taking dyes with it which form spots in different spaces
  5. 4 spots means at least 4 colours ( could be more e.g two similar colours )
43
Q

Advantages of using machines for chromatography

A

Very sensitive - can detect tiniest amount of substance

Very fast

Very accurate

44
Q

What is gas chromatography

A

Can be used to identify and separate substances out of a mixture of compounds

45
Q

How does gas chromatography work ?

A

Gas is used to carry substances through a column packed with a solid material

The substance travels at different speeds there separated

46
Q

What is retention time in gas chromatography

A

The time the substance reaches the detector is called the retention time it can be used to help identify substances

47
Q

What do the peaks on a gas chromatography graph represent

A

Different compounds in the sample

The position of hue peak shows the retention time

48
Q

What is a mass spectrometer

A

Identifies solvents/compounds/substances

49
Q

What are the 4 things that the rate of a reaction depends on

A
  1. Catalyst
  2. Temperature
  3. Surface area
  4. Concentration
50
Q

What is the formula for rate of reaction (ROR)

A

Amount of reactants used or products formed
ROR = _____________________
Time

51
Q

What is precipitation ?

A

This is when the product of the reaction is a precipitate which clouds the solution.

52
Q

( how to measure rates of reaction). How can you measure precipitation

A

Observe a mark through the solution and measure how long it takes to disappear.

(Only works for reactions when the solution stars of see through)

53
Q

Measuring rates of reaction 2

Change in mass ( usually given off by a gas)

A

This can be carried out on a mass balance

As the gas is released, the mass disappearing is measured on the balance

The quicker the reading of the balance drops the quicker the reaction

54
Q

Measuring rates of reaction 3

The volume of gas given off

A

Involves using a gas syringe to measure volume

The more gas given off during a set time interval the faster the reaction

55
Q

What is the structure like on simple molecules

E.g solid, liquid and gas

A

Substances that consist of simple molecules have only weak intermolecular forces between the molecules.

It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils.

56
Q

What is a catalyst ?

A

A catalyst is a substance that speeds up a reaction without being changed or used up

57
Q

How to catalyst help reduce costs in industry

A
  1. It speeds up the reaction meaning It does not Tia e as long to make the product
  2. Allows the reaction to take place in lowers temperatures which saves money
  3. That are not used up, so can be used over again.
58
Q

Define: exothermic

A

When energy/heat is give out

59
Q

Define: endothermic

A

When heat/energy is taken in

60
Q

What can reversible reactions be ?

A

Exothermic and endothermic

Energy absorbed by the reaction is the same as it being given out when reversed

61
Q

What is a indicator

A

A dye that changes colour

62
Q

What is an acid

A

A acid is a substance of a ph less than 7

Acids form H+ ions

63
Q

What is a base

A

A base is a substance with a ph of more than 7

An alkali is a base that dissolves in water

Alkalis form OH- ions

64
Q

What is the neutralisation formula

A

A acid and a base neutralise each other

H+ + OH- = H2O

65
Q

Formula for making salt

A

Acid + metal = salt + hydrogen

66
Q

Hydrochloride acid will make what type of salt

A

CHLORIDE salts

67
Q

Sulfuric acid will make what type of salt

A

SULFATE salts

68
Q

Nitric acids will produce what types of salts

A

NITRATE salts

69
Q

Combinations of metals and acids that make salts

Examples

A

hydroCHLORIC acid + COPPER oxide = COPPER CHLORIDE

SULFURIC acid + ZINC oxide = ZINC SULFATE

NITRIC acid + magnesium oxide = MAGNESIUM NITRATE

70
Q

IMPORTANT

Making insoluble salts - precipitation reaction

A

You just need to pick two solutions that contains the ions you need

E.g if making lead chloride you need lead ions and chloride ions

Once the salt has precipitated, you have to filter it from the solution , wash it then dry on filter paper

71
Q

What does ‘oil rig’ stand for

A

Oxidation
Is
Loss

Reduction
Is
Gain

72
Q

What is electrolysis ?

A

The splitting up of a substance using electricity

73
Q

How does electrolysis work ?

A

An electric current is passed through a ionic substance that’s molten or solution.

The substance that is broken down is called the electrolyte.

74
Q

What is oxidation

A

Is a gain of oxygen or a loss of electrons

75
Q

What is reduction

A

Is a loss of oxygen but a gain in electrons

76
Q

What is the half equation at the negative electrode

A

2H+ + 2e- = H2

77
Q

What is the half equation at the positive electrode

A

2Cl- + Cl2 = 2e-

78
Q

Useful products of the electrolysis of sodium chloride

A

Chlorine has many uses e.g bleach and plastics

Sodium hydroxide is a very strong alkali and is used for soap

79
Q

What else is electrolysis used for

A

Removing aluminium from its ore

80
Q

What is cryolite

A

It is used to lower temperature and costs

It is useful as many processes have high melting points which mean a industry has to use a lot of heat which is expensive

81
Q

What is electroplating

A

It uses electrolysis to coat the surface of one metal with another

82
Q

An example of why you would use electroplating

A

You may want to electroplated silver onto a brass cup to make it look nice

83
Q

Two reasons for electroplating

A
  1. Decoration, to make something look attractive

2. Conductors, metals like copper conduct electricity well

Additional Chemistry (1 decks)

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