Atomic Structure Flashcards Preview

LC Chemistry > Atomic Structure > Flashcards

Flashcards in Atomic Structure Deck (58)
Loading flashcards...
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
  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)

19
Q

Thomson’s plum pudding

A
  1. 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
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)