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Chemistry > Module 2.1 > Flashcards

Module 2.1 Flashcards

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1
Q

Mass and charge of protons, neutrons and electrons:

A

Protons: 1 +
Neutrons: 1 0
Electrons: Negligible, 1/1000 -

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2
Q

What does the mass number of an element tell us?

A

Protons + neutrons number

Average of the mass numbers of the isotopes of that element.

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3
Q

Define isotopes:

A

Atoms of the same element with different numbers of neutrons and masses.

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4
Q

Why is carbon 12 on the periodic table?

A

Because it is the most abundant carbon isotope.

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5
Q

Define RMM:

A

Relative molecular mass

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6
Q

What does (m/z) stand for?

A

Mass/ ion charged

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7
Q

Describe the current model of the atom:

A

Protons and neutrons in nucleus, centre of atom.

Electrons orbit in shells.

Nucleus is tiny compared to the volume of the atom.

The nucleus is extremely dense and accounts for most of the mass.

Most of the atom consists of empty space between the nucleus and ‘shells’.

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8
Q

Where is most of the mass in an atom?

A

In the nucleus

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9
Q

What is most of the volume in an atom?

A

The orbitals

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10
Q

How do isotopes differ?

A

Different masses

Different numbers of neutrons

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11
Q

What do isotopes of the same element have in common?

A

Same number of protons and electrons.

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12
Q

Why do different isotopes of the same element react in the same way?

A

Chemical reactions involve electrons, isotopes have the same number and arrangement.

Neutrons make no difference to chemical reactivity.

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13
Q

Why do different isotopes have different physical properties?

A

Densities and rates of diffusion differ because they depend more on mass.

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14
Q

How do we measure mass of element?

A

We compare different masses using relative mass.

Carbon 12 is the international standard for he measurement of relative mass.
Atomic masses are measured using the unified atomic mass unit.

Carbon 12s mass is defined as 12u, so 1/12 of carbon is 1u.

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15
Q

Define a molecule:

A

A group of atoms held together by covalent bonds.

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16
Q

What are the uses of mass spectrometry?

A

Identify unknown compounds
Relative abundance of each isotope of an element
Determine structural info about molecules

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17
Q

How is mass spectrometry carried out?

A

Causes substances to become positive ions, which are passed through the apparatus and separated according to their mass and charge.

A computer analyses the data and produces a mass spectrometer.

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18
Q

What unit are atomic masses measured in?

A

Unified mass unit (u)

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19
Q

Who came up with the original atomic theory and when?

A

Dalton, 1800s

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20
Q

What did Dalton’s theory consist of?

A

Atoms make up elements.
Atoms cannot be divided, they are solid spheres, different sphere, different element.
All atoms of an element are the same.
Atoms of one element are different from atoms of every other.

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21
Q

Who developed the second model of the atom and when?

A

Thomson, 1897-1906

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22
Q

What did thomsons model consist of?

A

Disproved atoms cannot be divided
Proposed negative corpuscles (electron) in a sea of positive charge
‘Plum pudding model’ positive sphere with electrons embedded in it
+tive and -tive charges balance out making a neutral atom.

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23
Q

Who and when discovered the 3rd model of the atom?

A

Rutherford, 1909-11

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24
Q

What did Rutherford model consist of?

A

Gold leaf experiment
Shot + alpha particles at a thin gold sheet
‘Plum pudding’ would hardy deflect any
Most were not deflected, a small % by large angles, some backwards towards the source
Came up with nuclear model to reflect his findings

Tiny positively charged nucleus at the centre of the atom, were most of the mass is concentrated. The nucleus is surrounded by a ‘sea’ of positive electrons. Most of the atom is empty space

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25
Who and when was the 4th model of the atom discovered?
Bohr, 1913
26
What did bohrs model consist of?
If electrons were in a cloud they'd spiral into the nucleus, causing the atom to collapse. He proposed they exist in fixed orbits, or shells and not anywhere in between. Each shell has fixed energy. When an electron moves between shells electromagnetic radiation is emitted or absorbed. Because the energy is fixed, the radiation will have a fixed frequency.
27
How did bohrs model explain the inert gases?
He said shells have fixed numbers of electrons, this causes an atoms reactivity. Atoms react in order to gain full shells of electrons, when it's shell is full, it does not react.
28
What is Avogadro's constant?
Number of atoms per mole of the carbon-12 isotope | 6.02 x 10^23mol-1
29
How to find moles from mass and molar mass?
moles = mass / molar mass
30
Ideal gas equation | What do the letters represent?
``` PV = nRT P = Pressure V = Volume n = Moles R = Gas constant, 8.314Jmol-1k-1 ```
31
What is 0 degrees in kelvin?
273
32
How much volume does one mole of gas take up (at room temperature)?
24000cm^3 | 24dm^3
33
Define amount of substance
he quantity that has moles as its unit
34
Define mole
Amount of any substance containing as many particles as there are in 12g of the carbon-12 isotope
35
Define Molar mass
mass per mole of a substance | g mol-1
36
How do you work out amount, in moles of any volume of a gaseous substance?
``` n = v (dm3) / 24 n = v (cm3) / 24000 ```
37
What is the SI unit for pressure?
Pascal Pa, 1 atmosphere = 101325
38
What is the SI for volume?
Cubic metres, m^3 | 1m^3 = 1000dm^3
39
What is the SI for temperature?
Kelvin | 0 degrees = 273 k
40
What is the value of R?
8.314 J mol -1 K-1
41
How do you work out amount in moles in a solution?
``` n = c x v (dm3) n = c x (Vcm3/1000) ```
42
Define concentration
Of a solution is the amount of solute in mol dissolved in one dm3 of solution
43
Define standard solution
A solution of known concentration. Usually used in titrations to determine unknown information about a different substance.
44
Define species
A type of particle that takes part in a reaction, atom, ion, molecule, empirical formula or electron.
45
How do you find percentage yield?
(Actual amount in mol of product / theoretical amount in mol of product) x 100
46
How do you find atom economy?
Molecular mass of required product / sum of molecular masses of all products x 100
47
What are the 3 most common acids in labs?
Sulfuric acid Hydrochloric acid Nitric acid
48
Formula of sulphuric acid
H2SO4
49
Formula of hydrochloric acid
HCl
50
Formula of nitric acid
HNO3
51
Where might you find sulphuric acid?
Battery acids in cars
52
Where might you find hydrochloric acid?
Present in stomach to digest food
53
Formula for ethanoic acid
CH3COOH
54
What is a use of ethanoic acid?
Vinegar
55
What happens to Hydrochloric acid in water?
H+ Cl-
56
What happens to sulphuric acid in water?
H+ HSO4-
57
What is a definition for an acid?
Proton donor
58
What are common Bases?
Metal oxides, Metal hydroxides
59
Formula for Ammonia
NH3
60
What is a use of magnesium hydroxide?
Milk of magnesia, treating acid indigestion
61
Formula of magnesium hydroxide
Mg(OH)2
62
Formula of calcium hydroxide
Ca(OH2
63
Use of calcium hydroxide
Used to reduce acidity of soil
64
Definition of a Base
Proton acceptor
65
Common lab alkalis
Sodium hydroxide Potassium hydroxide Ammonia
66
Describe how to make a standard solution
Wash out volumetric flask with distilled water Measure out solute into weighing boat Pour solute into flask, wash out boast with distilled water and pour into flask Add more distilled water and shake the flask so the solute dissolves Fill flask up to required volume with distilled water Invert flask with lid on
67
How do strong acids dissociate?
Fully
68
How do weak acids dissociate?
Partially
69
What are alkalis in terms of bases?
Soluble bases
70
Define Amphoteric substances
React both as acids and bases e.g.Amino acid which consists of : amino basic group NH2 which can accept proton and A carboxyl acid, COOH which can donate a proton
71
What are key features of salts?
Ionic compound Positive ion, cation usually a metal ion or ammonium ion Negative ion of anion, derived from an acid The formula is the same as its parent acid but H+ ions have been replaced by a positive ion
72
Define diprotic acid
An acid that can donate 2 protons per molecule to an aqueous solution
73
What is an acid salt?
E.g. Sulfuric acid has 2 hydrogen ions that can be replaced by a positive ion, diprotic. If only one hydrogen ion is replaced an acid salt is formed for example sodium hydrogensulfate. An acid salt can behave as an acid because hydrogen ions can be replaced to form a conventional salt.
74
Define hydrated
A crystalline compound containing water molecules
75
Define anhydrous
A substance that contains no water molecules
76
Define water of crystallisation
Water molecules that form an essential part of the crystalline structure of a compound
77
How can dot formula of hydrated salts be determined?
It's empirical formula gained from percentage or mass. | Experimental results
78
Describe how to carry out a titration
Using a pipette add a measured volume of one solution to a conical flask, add an indicator. Place the other solution in a burette. Add the solution in the burette to the conical flask until the reaction has just completed. End point. Measure the volume of solution added From the burette.
79
What does a titration tell you?
The volume of one solution that exactly reacts with the volume of another.
80
Oxidisation number of combined oxygen
-2
81
Oxidisation number of oxygen in peroxides
-1
82
Oxidisation number of combined hydrogen
+1
83
Oxidisation number of combined hydrogen in metal hydrides
-1
84
Oxidisation number of combined fluorine
-1
85
Define oxyanions
Negative ions that contain an element along with oxygen
86
Define oxidation
The loss of electrons, loss of hydrogen, gain of oxygen or an increase in oxidation number.
87
What is a redox reaction?
A reaction where both reduction and oxidation take place.
88
Define reduction
The gain of electrons, gain of hydrogen, loss of oxygen or a decrease in oxidation number.
89
What is a reducing agent?
A reagent that reduces; adds electrons to, another species.
90
What order would you consider hydrogen, oxygen and fluorine when working out oxidation numbers?
F H O

Chemistry (7 decks)

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