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Chemistry > Topic 1 - Key Concepts > Flashcards

Topic 1 - Key Concepts Flashcards

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1
Q

In a chemical equation, what is a reactant?

A

What you put into a reaction. Chemicals on the left hand side before the arrow

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2
Q

What do symbol equations show?

A

Atoms on both sides

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3
Q

Symbol equations need to be balanced. True or false?

A

True

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4
Q

Balance the equation:

H2SO4 + NaOH = Na2SO4 + H2O

A

H2SO4 + 2NaOH = NaSO4 + 2H2O

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5
Q

Name the 4 state symbols and what do they mean?

A

1) s - solid
2) l - liquid
3) g - gas
4) aq - aqueous (dissolved in water)

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6
Q

What is the ionic charge of hydrogen?

A

H+

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7
Q

What is the ionic charge of hydroxide?

A

OH-

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8
Q

What is the ionic charge of carbonate?

A

CO3 2-

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9
Q

What do ionic equations show?

A

The most important/ useful parts of a reaction

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10
Q

How do you write an ionic equation?

A

Look at the balanced symbol equation and take out any aqueous ions that are present on both sides of the equation

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11
Q

What does the toxic label on a chemical mean?

A

It can cause death by e.g. swallowing, breathing in, absorption from the skin

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12
Q

What does the harmful label on a chemical mean?

A

Can cause irritation, reddening or blistering of the skin

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13
Q

What does flammable mean?

A

Catches fire easily

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14
Q

What does the corrosive label on a chemical mean?

A

Destroys materials, including living tissues (e.g. eyes and skin)

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15
Q

What does oxidising mean?

A

Provides oxygen which allows other materials to burn more fiercely

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16
Q

What does environmental hazard mean?

A

Harmful to organisms and to the environment

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17
Q

Name 2 safety precautions you should take when handling corrosive chemicals

A

1) Wearing gloves to protect skin

2) Wearing goggles to prevent the chemical splashing into the eyes

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18
Q

What was the name of J J Thomson’s model of an atom?

A

The ‘plum pudding model’

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19
Q

What is the name of the model of atom that we believe in today?

A

The Bohr model

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20
Q

Who proved the ‘plum pudding model’ wrong?

A

Ernest Rutherford

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21
Q

Name the 3 sub-cellular particles in an atom and their charges

A

1) Protons - positive charge
2) Electrons - negative charge
3) Neutrons - no charge/ neutral

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22
Q

In an atom, where is the nucleus located?

A

In the centre of the atom

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23
Q

What makes up the nucleus of an atom?

A

Protons and neutrons

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24
Q

What charge does the nucleus have?

A

Positive - because there are no electrons in the nucleus, the protons cannot be cancelled out. Therefore, the nucleus remains positively charged

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25
Q

Where are electrons found in an atom?

A

They exist in shells/energy levels

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26
Q

How many electrons can be in each shell?

A

In the first shell, only 2 electrons can exist, and after that, there can only be 8 electrons present in each shell

27
Q

What is the relative mass of an electron?

A

1/2,000

28
Q

Why are electrons not counted when calculating the relative atomic mass?

A

Because they are so small, they have virtually no impact on the mass

29
Q

In an atom, there are always more electrons than protons. True or false?

A

False - the numbers of protons and electrons are always equal because they then make the atom neutral

30
Q

What does the atomic number tell you?

A

How many protons are i an atom. Every atom of an element has the same amount of protons

31
Q

What does the mass number tell you?

A

The total number of protons and neutrons in the atom. To work out neutrons, just take away toe atomic . number from the mass number

32
Q

What are isotopes?

A

Isotopes are the same element, but they have a different amount of neutrons

33
Q

Why are isotopes not classed as different elements?

A

Because they still have the same amount of protons

34
Q

What is the relative atomic mass?

A

The average mass of one atom of the element

35
Q

Who made the first proper periodic table?

A

Dmitri Mendeleev

36
Q

How does Mendeleev’s table differ from the modern day periodic table?

A

He ordered the elements by the mass number, whereas now we order the elements by the atomic number. He grouped his table according to an elements properties, and he left gaps where he believed new elements would be found

37
Q

What groups in the periodic table are most likely to form ions?

A

1 & 2 and 6 & 7

38
Q

What is ionic bonding?

A

The transfer of electrons from one atom to another

39
Q

What are the diagrams called to show ionic bonding?

A

Dot and cross diagrams- they show the electrons from the atom and the electrons that have come from the other atom

40
Q

What is the structure of an ionic compound?

A

A regular lattice

41
Q

What are the properties of an ionic compound?

A

1) High melting and boiling points due to the strong electrostatic forces between the ions. It takes a large amount of energy to overcome this attraction
2) Solid ionic compounds do not conduct electricity because the ions are fixed in place and cannot move. However, they do conduct electricity when it becomes a liquid
3) They are often dissolve easily in water

42
Q

What is a covalent bond?

A

A covalent bond is a strong bond that forms when a pair of electrons is shared between two atoms

43
Q

Give an example of a molecule with a covalent bond

A

Hydrogen (H2)
Methane (CH4)
Carbon dioxide (CO2)
Water (H2O)

44
Q

Give three properties of simple molecular structures

A
  • Usually have simple molecular structures
  • They have weak intermolecular forces, but strong covalent bonds
  • They do not conduct electricity
45
Q

What are polymers made out of?

A

Covalently bonded carbon chains

46
Q

How are polymers formed?

A

When small molecules called monomers join up, making a chain

47
Q

Give three properties of giant covalent structures

A
  • They have strong covalent bonds
  • They have a high melting and boiling point
  • They are insoluble in water
48
Q

Give three examples of giant covalent carbon-based structures

A
  • Diamond
  • Graphite
  • Fullerenes
49
Q

What are fullerenes?

A

Molecules of carbon which are shaped like closed tubes or hollow spheres
Mainly made up of carbon atoms arranged in hexagons, or sometimes pentagons and heptagons

50
Q

Give one use of fullerenes, and explain why it is useful

A

Because of their hollow sphere structure, they can be used to deliver a drug directly to cells in the body.
The fullerenes forms a cage-like structure around the drug

51
Q

What does metallic bonding involve?

A

Delocalised electrons

52
Q

What kind of structure do metals have?

A

Giant structure

53
Q

Give five properties of metals

A
  • The electrostatic forces are very strong
  • Have a very high melting and boiling point
  • Generally very dense
  • Malleable
  • Good conductors of heat and electricity due to delocalised electrons
54
Q

Give five properties of non-metals

A
  • Tend to be dull and brittle
  • Have relatively low melting and boiling points
  • Often have a low density
  • Generally don’t conduct electricity
  • Tend to gain electrons in order to fill their outer shells
55
Q

What is conservation of mass?

A

Everything that goes in a reaction will always come out of the reaction.

56
Q

If the mass changed in a reaction, what does this show?

A

If the mass increases, usually one of the reactants is a gas. If the mass decreases, then it is probably because some, or all of the reactants are solids, liquids or aqueous. Also, one of the products is usually a gas

57
Q

How do you work out the empirical formula?

A
  1. Mass numbers of elements - given in the question
  2. Relative mass numbers - see periodic table
  3. Divide these two masses
  4. Divide the answers of the masses with the smallest answer
  5. Simplify this ratio and work out the empirical formula
58
Q

What is empirical formula?

A

The empirical formula tells you the smallest whole number ratio of atoms in the compound

59
Q

What does “1 mole” mean?

A

The term “mole” is simply the name given to a certain number of particles
1 mole is equal to the relative atomic mass in grams, or Avogadro’s constant

60
Q

How do you calculate the number of moles?

A

Mass in grams / relative atomic mass

61
Q

What is Avogadro’s constant?

A

6.02 x 10^23

62
Q

How do you calculate concentration?

A

Mass of solute / volume of solution

63
Q

What is concentration measured in?

A

g dm^-3

64
Q

Explain an experiment on how to find an empirical formula

A

Magnesium oxide experiment using crucible, lid, gauze, tripod, Bunsen burner

  • Heat crucible until hot - makes sure crucible is clean and therefore no other substances interfere with results
  • Leave crucible to cool, and weigh it with lid
  • Add magnesium to crucible, and weigh with the lid
  • Heat crucible with magnesium and lid, but leave small space for oxygen to enter the crucible
  • Allow to cool and reweigh. Use the mass of magnesium oxide take away the mass of magnesium to work out the mass of the oxygen in the reaction

Chemistry (11 decks)

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