1
Q
Scientists
A
John Dalton William Crookes George Johnstone Stoney J.J Thomson Robert Milikan Ernest Rutherford Niels Bohr James Chadwick
2
Q
John Dalton- discovered
A
Atomic theory
3
Q
John Dalton - how
A
Through experiments he performed with gases
4
Q
William Crookes - discovered
A
Cathode rays
5
Q
William Crookes - how
A
Negative electrode rays cast shadow of maltese cross in a vacuum tube
6
Q
George Johnstone Stoney - discovered
A
Named the electron
7
Q
George Johnstone Stoney - how
A
Proposed name in 1981
8
Q
J.J Thomson - discovered
A
Electrons have a negative charge
9
Q
J.J Thomson - how
A
- Sent cathode ray through positive electrode, then through 2 parallel plates
- When plates weren’t charged, ray went straight through, but if top one was positive, ray went upwards
10
Q
Robert Millikan - discovered
A
Magnitude of charge of electrons as shown by oil drops experiment
11
Q
Robert Millikan - how
A
- Sprayed tiny oil droplets between 2 charged metal plates, used x-rays to ionise air between plates
- Oil droplets fell through air
- Oil droplet attached to positively charged plate
- Made the droplet stationary + from measurements, he was able to calculate charge of electron
12
Q
Ernest Rutherford - discovered
A
Discovering of nucleus as shown by particle scattering experiment, discovering of protons in nuclei of various atoms
13
Q
Ernest Rutherford - how
A
- Bombarded gold foil with Alpha particles
- used detector for scattered a-particles
- most went straight through, some deflected largely, some reflected
- showed that gold foil had nuclei - which when hit, positive alpha particles repelled them
14
Q
Niels Bohr - discovered
A
Model of atom
15
Q
Niels Bohr - how
A
Used experimental evidence to prove electrons occupy particular orbits or shells around nucleus of atom
16
Q
James Chadwick - discovered
A
Discovered the neutron
17
Q
James Chadwick - how
A
- Bombarded beryllium with alpha particles
- Discovered some particle with no charge was coming from beryllium
- They were knocking protons from beryllium
- Found that these particles had same mass as protons + named them neutrons
18
Q
Dalton’s Atomic Theory
A
- All matter is made up of very small particles called atoms
- All atoms are indivisible. Cannot be broken down into simpler particles
(3. identical atomic mass for particular element)
19
Q
Thomson’s plum pudding
A
- Atom is like a sphere of positive charge
2. Electrons embedded in sphere at random
20
Q
Problem with Plum Pudding model
A
Explained why atoms were neutral but Thomson did not have experimental evidence
21
Q
Mass Spectrometer
A
Instrument capable of separating + recording relative amounts of isotopes of an element.
22
Q
Mass Spectrometer topics (processes)
A
Sample intro Vaporisation Ionisation Separation of ions Detection
23
Q
Mass Spectrometer
A
- Sample to be analysed is injected into instrument
- Vaporised
- Ionised by bombardment with beam of high-energy electrons.
- Positive ions produced are accelerated through slit, using electric field, deflected along circular path using magnetic field
- Degree of curvature depends on mass of ion)
- Separated into beams of ions of similar masses in this way
- Detected electronically
- Vacuum inside so ions don’t clash with air molecules
24
Q
Mass Spectrometer - molecules
A
- Can be used to determine relative molecular mass of substance composed of molecules
- Molecules ionised + broken into positively charged fragments w/ different masses
- Separated
- Relative amounts recorded, giving mass spectrum of molecume
- Mass of this ion is same as relatie molecular mass of molecule
25
Molecule
Group of atoms joined together. It is the smallest particle of an element or compound that can exist independently
26
Ion
Charged atom/group of atoms
27
Compound
Substance made of two or more elements
28
Atom
Basic unit from which all substances are formed
29
Relative Atomic Mass (Ar)
Average of the mass numbers of the isotopes of the element as they occur naturally taking their abundances into account relative to the 1/12th mass of carbon 12 atom
30
Isotope
Atoms of the same element that have different mass numbers due to different number of neutrons in nucleus
31
Law of conservation of mass
Total mass of products of a chemical reaction is same as total mass of reactants
32
types of particles
Proton
Neutron
Electron
33
Proton charge
+1
34
Neutron charge
0
35
Electron charge
-1
36
Proton mass
1
37
Neutron mass
1
38
Electron mass
1/1838
39
Proton position
Nucleus
40
Neutron position
Nucleus
41
Electron position
Shells around nucleus
42
what term is used to refer to the condition of the hydrogen atom when its electron occupies the E1 level?
ground state
43
what term is used for the condition of the hydrogen atom when its elecron occupies any of the E2, E3, etc?
excited states
44
what causes the electron to leave the E1 level?
it acquires energy (heat/electricity)
45
why does the electron not remain in any of the levels E2, E3, etc?
higher energy states unstable
46
visible lines in a.emission spectrum produced when electrons fall to a particular energy level. What is this energy level?
E2 / n = 2 / second
47
how does modern atomic theory describe the behaviour of electrons?
electrons have both wave and particle properties
48
why relative atomic masses are rarely whole numbers
average of mass numbers of isotopes of an element
49
ways to detect the presence of cathode rays in a vacuum tube
- fluorescence
- glow
- coloured light
- shadow cast by anode (cross,object)
50
three observations made by Rutherford's team when they bombarded gold foil with alpha particles
- most alpha-particles undeflected, passed straight through gold foil
- some alpha particles deflected
- some reflected straight back along their original paths
51
explain how rutherford deduced from their observations that the nucleus is positive
repulstion of positive alpha particles
52
explain how rutherford deduced from their observations that the nucleus is negative
- most alpha-particles undeflected, passed straight through gold foil
- a few alpha particles deflected straight back
53
what contribution did Newlands make to the systematic arrangement of elements?
- arranged in increasing relative atomic mass/atomic weight
| - law of octaves - repeat every eighth elements
54
graphs
- use graph paper
- make sure to join points and plot correctly
- label and scale axes properly!
55
mass number
number of nucleons (protons and neutrons) in the atoms of an isotop
56
a sample of the element gallium is composed of 60.1% galium-69 and 39/9% gallium-71. Calculate the relative atomic mass of it from this info
69 x 60.1 = 4146.9
71 x 39.9 = 2832.9
100 atoms = 6979.8
Ar = 6979.8 / 100
= 69.798
57
what is the colour of light associated with the line emission spectrum of sodium?
yellow/orange
58
explain how Rutherford interpreted the results of his experiment to conclude atom has a nucleus
the only possible explanations for the observations are:
- atom is mostly empty space
- positive charge concentrated (contained in small space)
LC Chemistry
flashcards
Decks in class (26)
# Cards
-
The Periodic Table40
-
Atomic Structure58
-
Radioactivity38
-
Electronic Structure of Atoms79
-
Fuels and Heats of reaction122
-
Trends in the Periodic Table23
-
Organic Chemistry88
-
Reactions in Organic Chemistry - Substitution Reaction22
-
Reactions in Organic Chemistry - Addition Reaction37
-
Water127
-
Acids and Bases103
-
Oxidation Numbers68
-
Warning symbols0
-
chemical bonding93
-
shapes and forces40
-
Gas Laws and the Mole63
-
atmospheric chemistry111
-
instrumentation34
-
industrial chemistry52
-
rates of reaction97
-
chemical equilibrium83
-
Experiments296
-
THERMOCHEMISTRY0
-
Organic Chem exam qs44
-
Definitions46
-
reminders4
