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Chemistry > Key Concepts > Flashcards

Key Concepts Flashcards

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1
Q

Products

A

Appear on the right hand side of an equation, have been produced from reactants.

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2
Q

Reactants

A

Appear on the left hand side of an equation, react to form products.

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3
Q

Three types of equation

A

Word equation (simple, says which molecules are involved but not what happens)
Symbol equation (show which molecules are involved using chemical symbols and which chemical changes have occurred)
Ionic equations (show only reacting particles and the products formed)

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4
Q

State Symbols

A

(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous (dissolved in water)

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5
Q

methane + oxygen ->

A

carbon dioxide and water

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6
Q

H2O

A

water

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7
Q

CO2

A

carbon dioxide

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8
Q

Cl2

A

chlorine

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9
Q

NH3

A

ammonia

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10
Q

H2

A

hydrogen

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11
Q

O2

A

oxygen

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12
Q

NH4+

A

ammonium

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13
Q

NO3-

A

nitrate

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14
Q

SO42-

A

sulfate

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15
Q

OH-

A

hydroxide

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16
Q

CO32-

A

carbonate

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17
Q

Oxidising

A

Provides oxygen which allows other materials to burn more fiercely.

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18
Q

Hazard

A

Anything that has the potential to cause harm or damage.

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19
Q

Risk

A

The probability of something or someone being harmed if they are exposed to the hazard.

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20
Q

Harmful

A

Can cause irritation, reddening or blistering of the skin.

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21
Q

Environmental Hazard

A

Harmful to organisms and to the environment.

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22
Q

Highly Flammable

A

Catches fire easily

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23
Q

Toxic

A

Can cause death (through swallowing, breathing in, absorption through skin etc).

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24
Q

Corrosive

A

Destroys materials including living tissues.

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25
Q

Atoms

A

Tiny particles of matter which make up everything in the universe

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26
Q

John Dalton

A

Start of the 19th century, atoms are solid spheres and different spheres make up different elements

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27
Q

J J Thomson

A

1897, atoms are not solid spheres, atoms contain smaller, negatively charged particles (electrons), the plum pudding model

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28
Q

Ernest Rutherford

A

1909, the gold foil experiment, the nuclear atom, a tiny positively charges nucleus surrounded by a cloud of negatively charged electrons.

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29
Q

The Gold Foil Experiment

A

Positively charged alpha particles fired at an extremely thin sheet of gold, many particles went through (showing the empty space) but many also rebounded (a centred mass with a cloud of electrons)

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30
Q

Niels Bohr

A

Electrons sit in shells around the nucleus, they can only exist in fixed orbits and each shell has a fixed energy.

31
Q

Subatomic Particles

A

Electron, neutron, proton

32
Q

Electron

A
  • negatively charged
  • relative mass of 0.0005
  • around the nucleus in shells
  • equal the number of protons in an atom (shown by atomic number)
33
Q

Protons

A
  • positively charged
  • relative mass of 1
  • found in the nucleus
  • are equal to the number of electrons in an atom
  • shown by atomic number
34
Q

Neutron

A
  • no charge (neutral)
  • relative mass of 1
  • found in the nucleus
  • make up part of the mass number (mass number - atomic number = neutrons)
35
Q

Isotopes

A

Atoms from the same element which have the same number of protons but a different number of neutrons.

36
Q

Relative Atomic Mass (Ar)

A

The relative atomic mass is an average of all isotopes of an element
relative isotope mass (1) * abundance (1) + relative isotope mass (2) * abundance (2)/abundance = relative atomic mass

37
Q

Dmitri Mendeleev

A

1869, first arrangement of the elements known at the time
- sorted into groups based on properties
- ordered based on atomic mass with similar chemical properties in the same column
- when the atomic mass did not line up with chemical properties (due to isotopes) some were switched
- gaps were left to predict undiscovered elements

38
Q

Periodic Table

A
  • elements are ordered by atomic number
  • matching chemical properties form columns called groups
  • group number corresponds to the number of electrons in an atoms outer shell
  • periods (rows) show the number of electron shells an atom has
39
Q

Electron Shells

A
  • electrons always occupy a shell
  • the lowest energy levels (closest to nucleus) are always filled first
  • only a specific number of electrons are allowed in each shell (2.8.8.20)
40
Q

Ions

A

charged particles which are formed when an atoms gains or loses an electron (to have a full outer shell- stable)

41
Q

Anions

A

Negative ions, have gained electrons and have more electrons then protons

42
Q

Cations

A

Positive ions, when atoms lose electrons, more protons then electrons

43
Q

Groups which form anions

A

4, 5, 6, 7

44
Q

Groups which form cations

A

1, 2, 3, 4

45
Q

Ionic Bonding

A
  • between a metal and a non metal
  • metal atoms forms a cation
  • non metal atom forms an anion
  • transfer of electrons
  • anion and cation are attracted strongly through electrostatic forces
  • dot and cross diagrams
46
Q

Ionic Compounds

A
  • giant, regular, lattice structures
  • strong electrostatic forces between oppositely charged ions in all directions
47
Q

Ionic Compound Properties

A
  • high melting and boiling points (strong electrostatic forces between ions)
  • solid ionic compounds do not conduct electricity (ions are fixed in place)
  • molten of liquid ionic compounds can conduct electricity (ions are free to move)
  • many dissolve easily in water
48
Q

2D Representations

A

+ simple
+ show which atoms something contains
+ how the atoms are connected

  • do not show the shape of the substance
  • do not show the sizes of the atoms
49
Q

Dot and Cross Diagrams

A

+ useful for showing how compounds or molecules are formed
+ show where the electrons in the bonds/ions came from

  • do not show shape of atom/ions
  • do not show arrangement of atoms/ions
50
Q

3D Models

A

+ show arrangement of ions

  • only show the outer layer of the substance
51
Q

Ball and Stick Models

A

+ help to visualise structures
+ more realistic then 2D

  • may be misleading, gaps between atoms
  • incorrect scales
52
Q

Covalent Bonding

A
  • between non metals
  • sharing of electrons
  • atoms join in an attempt to form a full outer shell
  • typically form simple molecular substances
  • dot and cross diagrams
53
Q

Simple Molecular Substances

A
  • atoms within molecules are held together by strong covalent bonds
  • forces of attraction between molecules are weak
  • low melting and boiling points
  • most are gases and liquids at room temperature
  • do not conduct electricity
  • some are soluble
54
Q

Giant Covalent Structures

A
  • all atoms are bonded by strong covalent bonds
  • high melting and boiling points
  • do not generally conduct electricity
  • are not soluble in water
55
Q

Properties of Diamond

A
  • carbon atoms that form 4 covalent bonds
  • high melting point
  • rigid lattice structure
  • very hard (used in cutting tools)
  • does not conduct electricity
56
Q

Properties of Graphite

A
  • carbon atoms that form 3 covalent bonds
  • sheets of carbon atoms
  • layers held together weakly
  • soft and slippery (used in lubricants)
  • high melting point
  • conducts electricity
57
Q

Properties of Graphene

A
  • one layer of graphite
  • one atom thick
58
Q

Fullerenes

A
  • molecules of carbon
  • shaped like closed tubes or hollow balls
  • can cage other molecules (used for delivering drugs)
  • large surface area
59
Q

Nanotubes

A
  • fullerene
  • tiny cylinders of graphene
  • conduct electricity
  • high tensile strength
60
Q

Buckminsterfullerene

A
  • molecular formula of C60
61
Q

Metallic Bonding

A
  • electrostatic attraction between positive metal ions and negative shared delocalised electrons
  • forces of attraction hold atoms together in a regular structure
  • very strong bonds
62
Q

Physical Properties of Metal

A
  • very strong
  • high melting and boiling points
  • shiny solids at room temperature
  • are not soluble in water
  • very dense
  • malleable
  • conductors of electricity and heat
63
Q

Physical Properties of Non-Metals

A
  • dull
  • more brittle
  • lower boiling points
  • don’t conduct electricity
  • lower density
64
Q

Conservation of Mass

A

In a closed system, the mass of reactants equals the mass of products

65
Q

What has happened if the mass increases?

A
  • one of the reactants is a gas
  • the gas is not included in the mass of reactants
  • the gas is included in the mass of products
66
Q

What has happened if the mass decreases?

A
  • at least one of the products is a gas
  • if it is not enclosed then the gas will escape
  • the gas will be included in the mass of reactants but not the mass of products
67
Q

What is relative formula mass or Mr?

A
  • the relative atomic masses (Ar) of all the atoms in a compound added together
  • Mr is equal to the mass (in grams) of 1 mole
68
Q

What is the empirical formula?

A
  • simplest ratio of atoms in a compound
69
Q

What is Avogadro’s constant?

A
  • 6.02 x 1023
70
Q

Mass in grams (of element or compound) =

A

Mr (of compound) or Ar (of element) x Number of Moles

71
Q

Mass of solute in grams (solid you are dissolving) =

A

concentration (g dm-3) x volume of solution (dm3)

72
Q

What is an experiment used to find the empirical formula of a metal oxide?

A
  • weigh a crucible and its lid
  • add metal and reweigh the crucible, lid and metal
  • heat the crucible on a bunsen burner
  • allow oxygen to enter the crucible occasionally
  • reweigh to find the mass of metal oxide
73
Q

What is a limiting reactant?

A
  • the reactant that is fully used up
  • causes the reaction to stop
  • amount of product formed is directly proportional to the limiting reactant

Chemistry (9 decks)

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