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LC Chemistry > Atomic Structure > Flashcards

Atomic Structure Flashcards

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1
Q

Scientists

A 
John Dalton
William Crookes
George Johnstone Stoney
J.J Thomson
Robert Milikan
Ernest Rutherford
Niels Bohr
James Chadwick
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2
Q

John Dalton- discovered

A

Atomic theory

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3
Q

John Dalton - how

A

Through experiments he performed with gases

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4
Q

William Crookes - discovered

A

Cathode rays

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5
Q

William Crookes - how

A

Negative electrode rays cast shadow of maltese cross in a vacuum tube

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6
Q

George Johnstone Stoney - discovered

A

Named the electron

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7
Q

George Johnstone Stoney - how

A

Proposed name in 1981

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8
Q

J.J Thomson - discovered

A

Electrons have a negative charge

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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
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10
Q

Robert Millikan - discovered

A

Magnitude of charge of electrons as shown by oil drops experiment

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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
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12
Q

Ernest Rutherford - discovered

A

Discovering of nucleus as shown by particle scattering experiment, discovering of protons in nuclei of various atoms

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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
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14
Q

Niels Bohr - discovered

A

Model of atom

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15
Q

Niels Bohr - how

A

Used experimental evidence to prove electrons occupy particular orbits or shells around nucleus of atom

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16
Q

James Chadwick - discovered

A

Discovered the neutron

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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
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18
Q

Dalton’s Atomic Theory

A
  1. All matter is made up of very small particles called atoms
  2. All atoms are indivisible. Cannot be broken down into simpler particles

(3. identical atomic mass for particular element)

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19
Q

Thomson’s plum pudding

A
  1. Atom is like a sphere of positive charge

2. Electrons embedded in sphere at random

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20
Q

Problem with Plum Pudding model

A

Explained why atoms were neutral but Thomson did not have experimental evidence

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21
Q

Mass Spectrometer

A

Instrument capable of separating + recording relative amounts of isotopes of an element.

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22
Q

Mass Spectrometer topics (processes)

A 
Sample intro
Vaporisation
Ionisation
Separation of ions
Detection
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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
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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
Q

Molecule

A

Group of atoms joined together. It is the smallest particle of an element or compound that can exist independently

26
Q

Ion

A

Charged atom/group of atoms

27
Q

Compound

A

Substance made of two or more elements

28
Q

Atom

A

Basic unit from which all substances are formed

29
Q

Relative Atomic Mass (Ar)

A

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
Q

Isotope

A

Atoms of the same element that have different mass numbers due to different number of neutrons in nucleus

31
Q

Law of conservation of mass

A

Total mass of products of a chemical reaction is same as total mass of reactants

32
Q

types of particles

A

Proton
Neutron
Electron

33
Q

Proton charge

A

+1

34
Q

Neutron charge

A

0

35
Q

Electron charge

A

-1

36
Q

Proton mass

A

1

37
Q

Neutron mass

A

1

38
Q

Electron mass

A

1/1838

39
Q

Proton position

A

Nucleus

40
Q

Neutron position

A

Nucleus

41
Q

Electron position

A

Shells around nucleus

42
Q

what term is used to refer to the condition of the hydrogen atom when its electron occupies the E1 level?

A

ground state

43
Q

what term is used for the condition of the hydrogen atom when its elecron occupies any of the E2, E3, etc?

A

excited states

44
Q

what causes the electron to leave the E1 level?

A

it acquires energy (heat/electricity)

45
Q

why does the electron not remain in any of the levels E2, E3, etc?

A

higher energy states unstable

46
Q

visible lines in a.emission spectrum produced when electrons fall to a particular energy level. What is this energy level?

A

E2 / n = 2 / second

47
Q

how does modern atomic theory describe the behaviour of electrons?

A

electrons have both wave and particle properties

48
Q

why relative atomic masses are rarely whole numbers

A

average of mass numbers of isotopes of an element

49
Q

ways to detect the presence of cathode rays in a vacuum tube

A
  • fluorescence
  • glow
  • coloured light
  • shadow cast by anode (cross,object)
50
Q

three observations made by Rutherford’s team when they bombarded gold foil with alpha particles

A
  • most alpha-particles undeflected, passed straight through gold foil
  • some alpha particles deflected
  • some reflected straight back along their original paths
51
Q

explain how rutherford deduced from their observations that the nucleus is positive

A

repulstion of positive alpha particles

52
Q

explain how rutherford deduced from their observations that the nucleus is negative

A
  • most alpha-particles undeflected, passed straight through gold foil
  • a few alpha particles deflected straight back
53
Q

what contribution did Newlands make to the systematic arrangement of elements?

A
  • arranged in increasing relative atomic mass/atomic weight

- law of octaves - repeat every eighth elements

54
Q

graphs

A
  • use graph paper
  • make sure to join points and plot correctly
  • label and scale axes properly!
55
Q

mass number

A

number of nucleons (protons and neutrons) in the atoms of an isotop

56
Q

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

A

69 x 60.1 = 4146.9
71 x 39.9 = 2832.9

100 atoms = 6979.8

Ar = 6979.8 / 100
= 69.798

57
Q

what is the colour of light associated with the line emission spectrum of sodium?

A

yellow/orange

58
Q

explain how Rutherford interpreted the results of his experiment to conclude atom has a nucleus

A

the only possible explanations for the observations are:

  • atom is mostly empty space
  • positive charge concentrated (contained in small space)

LC Chemistry (26 decks)

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