Chemistry Module 2 Flashcards

1
Q

What is an isotope?

A

Atoms with the same number of protons and different number of neutrons

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2
Q

why do isotopes have the same chemical properties?

A

Isotopes have the same configuration of electrons

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3
Q

Explain why isotopes can have different physical properties

A

Physical properties depend on the mass of the atom

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4
Q

What is relative atomic mass?

A

The weighted mean mass of an atom of an element compared to 1/12 of the mass of a carbon 12 atom

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5
Q

What is relative isotopic mass?

A

The weighted mean mass of an isotope compared with 1/12 the mass of a carbon 12 atom

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6
Q

What is relative molecular mass

A

The average mass of a molecule compared to 1/12 of the mass of a carbon 12 atom

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7
Q

What is relative formula mass?

A

The average mass of a formula unit compared to 1/12 the mass of a carbon 12 atom

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8
Q

How to calculate relative molecular mass

A

Amount of atom of one element + atomic mass x amount of other atoms of the element + atomic mass

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9
Q

How to calculate relative formula mass

A

product of the amount of atoms of the elements

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10
Q

Explain the term amount of substance

A

Number of particles measured using a unit called the mole (n)

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11
Q

What formula finds the number of moles from the number of atoms or molecules?

A

Number of moles = Number of particles you have

Number of particles in a mole

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12
Q

What is molar mass?

A

The mass per mole of a substance (gmol-1)

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13
Q

What is the formula that finds number of moles from the molar mass?

A

Number of moles = mass of substance

molar mass

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14
Q

What is molar gas volume?

A

The gas volume per mole (dm3mol-1)

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15
Q

What are two formulas that finds the number of moles in a volume of gas?

A

Number of moles = volume of dm3/cm3

24/24000

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16
Q

What is the ideal gas equation?

A

pV = nRT pressure(Pa) x volume(m3) =

moles x temperature(K) x the gas constant(JK-1mol-1)

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17
Q

What is the procedure required to measure gas volumes?

A

Connect the gas syringe to the container to collect all gas produced by a reaction.
As the gas is produced the plunger is pushes out the syringe and the volume of gas collected can be read

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18
Q

What are the techniques required to measure gas volumes?

A

.

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19
Q

What is the formula that finds the number of moles from concentration and volume?

A

Number of moles = Concentration x volume in cm3/dm3

1000/1

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20
Q

What does the empirical formula tell you?

A

The simplest whole number ratio of atoms of each element present in a compound

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21
Q

What does the molecular formula tell you?

A

The actual number and type of atoms of each element in a molecule

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22
Q

What is the formula for nitrate?

A

NO3-

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23
Q

What is the formula for carbonate?

A

CO32-

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24
Q

What is the formula for sulfate?

A

SO42-

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25
Q

What is the formula for ammonium?

A

NH4+

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26
Q

What is an acid?

A

A proton donor which releases H+ ions in aqueous solution

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27
Q

What is a base?

A

A proton acceptor which releases OH- ions in aqueous solution

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28
Q

What is the formula of sulfuric acid?

A

H2SO4

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29
Q

What is the formula for nitric acid?

A

HNO3

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30
Q

What is the formula for ethanoic acid?

A

CH3COOH

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31
Q

what is the formula for ammonia?

A

NH3

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32
Q

Explain a strong acid?

A

The acid fully ionizes in solution and releases and lots of H+ ions

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33
Q

Explain a weak acid?

A

Only a small amount of the acid ionizes and releases a little amount of H+ ions

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34
Q

What is a neutralisation reaction?

A

The reaction where H+ and OH- ions form H2O

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35
Q

What does an acid-base reaction produce?

A

Salt + water

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36
Q

What does an acid-metal reaction produce?

A

Salt + hydrogen

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37
Q

What does an acid-metal oxide reaction produce?

A

Salt + water

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38
Q

What does an acid-metal hydroxide reaction produce?

A

Salt + water

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39
Q

What does an acid-metal carbonate reaction produce?

A

Salt + carbon dioxide + water

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40
Q

What does anhydrous salt mean?

A

The salt doesn’t contain water of crystallization

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41
Q

What does hydrated salt mean?

A

A salt containing water of crystallization

42
Q

What does water of crystallization mean?

A

The water in a lattice

43
Q

How to calculate the formula of a hydrated salt?

A

. Find the mass of water lost (mass of hydrated salt - mass of anhydrous salt)
. Find the number of moles of water lost
. Find the number of moles of anhydrous salt produced
. Work out the ratio of moles of anhydrous salt to moles of water

44
Q

What is a titration?

A

Titrations allow you to find out exactly how much acid is needed to neutralise a quantity of alkali

45
Q

How to perform an acid-base titration

A

. Measure out some alkali using a pipette and put it in a flask with a few drops of indicator (phenolphthalein)
. Take an initial reading to see how much acid is in the burette to start off with
. Add the acid to the alkali swirling the flask continuously
. Stop when the indicator shows a permanent colour change (colourless)
. Record the final reading from the burette

46
Q

How to calculate concentration using a titration

A

. Work out moles (conc x col in cm3 ./. 1000)

. work out conc (moles x 1000 ./. vol in cm3)

47
Q

How to calculate the volume using a titration

A

. Work out moles (conc x vol in cm3 ./. 1000)

. work out vol ( moles x 1000 ./. conc)

48
Q

What is meant by theoretical yield?

A

The mass of product that should be formed in a chemical reaction

49
Q

How to calculate theoretical yield

A

. work out moles of the limiting reactant
. work out the moles of product that the reactant should make
. calculate the mass of that many moles of product

50
Q

What is meant by percentage yield?

A

The actual amount of product you collect

51
Q

What formula finds percentage yield?

A

Percentage yield = Actual yield

Theoretical yield x100

52
Q

What is meant by atom economy?

A

a measure of the proportion of reactant atoms that become part of the desired product

53
Q

How to calculate atom economy

A

. Find the molar mass of the desired product
. Find the molar mass of the products
. Use the equation (mr of desired product
sum of molar mass of all products x100

54
Q

Why are reactions with low atom economy not used in industry?

A

. there’s lots of waste produced
. expensive to dispose of waste products safely
. less sustainable

55
Q

What are the rules for assigning oxidation numbers

A
  1. uncombined elements = 0
  2. simple monatomic ion = same as its charge
  3. each atom in molecular ions = sum of there oxidation numbers
  4. Neutral compound (2cl- mg2+) = 0
  5. oxygen = -2 except in peorxides (O22-) = -1
  6. Hydrogen = +1 except in metal hydrides (MHx) = -1
56
Q

what does the oxidation number tell you?

A

the total number of electrons it has donated or accepted to form an ion or part of a compound

57
Q

What is a redox reaction?

A

Reduction and oxidation happen simultaneously

58
Q

What is oxidation?

A

loss of electrons

59
Q

What is reduction?

A

gain of electrons

60
Q

what is the role of an oxidising agent?

A

accepts electrons from another reactant and is reduced

61
Q

What is the role of a reducing agent?

A

donated electrons to another reactant and is oxidised

62
Q

How many orbitals make up the s subshell?

A

1

63
Q

How many orbitals make up the p subshell?

A

3

64
Q

How many orbitals make up the d subshell?

A

5

65
Q

How many electrons can fill up the s subshell?

A

2

66
Q

How many electrons can fill up the p subshell?

A

6

67
Q

How many electrons can fill up the d subshell?

A

10

68
Q

How many electrons can fill the first four shells?

A

2,8,18,32

69
Q

what are atomic orbitals?

A

A region around the nucleus that can hold up two two electrons with opposite spins

70
Q

What is meant by electron configuration?

A

The number of electrons that an atom or ion has and how they are arranged in different ways

71
Q

what is the shape of the s and p subshells?

A

spherical and dumbell

72
Q

What is an electron spin?

A

the momentum that an electron has

73
Q

Describe ionic bonding

A

The electrostatic attraction between positive and negative ions

74
Q

what causes the structure of a giant ionic lattice?

A

when oppositely charged ions from an ionic bond

75
Q

Explain what an ionic lattice is?

A

The same basic unit repeated formed because each ion electrostatically attracted in all directions to ions of opposite charges.

76
Q

what are the physical properties of ionic compounds?

A

. conducts electricity when molten or dissolved - the ions are free to move and carry charge
. high melting and boiling point - held together by strong electrostatic forces that need lots of energy to overcome
. soluble in water - water molecules are polar and part of the molecule has a small negative charge and positive charge so water molecules pull the ions away from the lattice and cause it to dissolve

77
Q

Define covalent bond

A

Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

78
Q

What happens in a dative covalent bond

A

one of the atoms provides both of the shared electrons

79
Q

What is average bond enthalpy?

A

measures the energy required to break a covalent bond

80
Q

what is the electron shell repulsion theory?

A

The theory that in a molecule lone pair- lone pair bond angles are the biggest, lone pair-bonding pair are the second and bonding pair-bonding pair are the smallest because lone pairs repel more

81
Q

what shape name is a atom with three electron pairs?

A

Trigonal planar(BF3)- the repulsion of the bonded pairs are equal and form a bond angle of 120.

82
Q

what shape name is a atom with two electron pairs?

A

Linear(BeCl)- the bonded pairs repel the same and are as far away from each other creating a bond angle of 180.

83
Q

what shape name is a atom with two electron pairs and one lone pair?

A

Non-linear - The lone pair repels more than the bonding pairs and creates a bond angle of less than 120.

84
Q

what shape name is a atom with three electron pairs and one lone pair?

A

Trigonal pyramidal(NH3)- There is a larger bond angle between the lone pairs than the bonding pairs creating a bond angle of 107.

85
Q

what shape name is a atom with four electron pairs?

A

Tetrahedral(CH4) - The charge clouds all repel equally creating a bond angle of 109.5

86
Q

what shape name is given to an atom with two electron pairs and two bonding pairs?

A

Bent(H2O)- the lone pair-lone pair repulsion makes the bond angle smaller and creates a bond angle of 104.5.

87
Q

what shape name is given to an atom with five bonding pairs?

A

Trigonal bipyramidal(PCl5)- repulsion between the bonding pairs means three will form a trigonal planar with bond angle 120. and the other two atoms will be 90. to them

88
Q

what shape name is given to an atom with six bonding pairs?

A

Octahedral(SF3)- all of the bond angles in the molecule are 90.

89
Q

Define electronegativity

A

the ability of an atom to attract the bonding electrons in a covalent bond

90
Q

How to use Pauling electronegativity values to predict the type of bond that will form between atoms

A

electronegativity is measured on the pauling scale- a higher number means an element is better able to attract the bonding electrons

91
Q

What is the trend in electronegativity

A

Electronegativity increases across periods and decreases down groups so fluorine is the most electronegative element

92
Q

why do polar bonds have permanent dipole dipoles

A

The covalently bonded atoms have different electronegativities causing a permanent dipole

93
Q

what is a dipole?

A

the difference in charge between the two atoms caused by a shift in electron density in the bond

94
Q

what are permanent dipole dipole interactions?

A

delta positive and delta negative charges on polar molecules cause weak electrostatic forces of attraction between molecules

95
Q

what are intermolecular forces?

A

forces between molecules depending on the induced and permanent dipole-dipole interactions

96
Q

what are induced dipole-dipole interactions

A

a weak attraction caused when there is a disruption in the arrangement of electrons in a non-polar molecule

97
Q

what is the structure of a simple molecular lattice?

A

covalently bonded molecules attracted by intermolecular forces

98
Q

what is hydrogen bonding

A

intermolecular bonding between molecules containing N,O or F and the H atom of -NH, -OH or HF

99
Q

What are the anomalous properties of H2O resulting from hydrogen bonding?

A

.High melting point

. Low density

100
Q

what are the physical properties of simple covalent compounds?

A

. can’t conduct electricity- covalent molecules are uncharged
. low melting and boiling point- the intermolecular forces are weak and don’t need much energy to break
. insoluble - covalent molecules are non-polar