Chapter 4 Flashcards Preview

Astronomy 101 > Chapter 4 > Flashcards

Flashcards in Chapter 4 Deck (79)
Loading flashcards...
1
Q

How much of the universe is Helium?

A

24%

2
Q

How much of the universe is Hydrogen?

A

75%

3
Q

Who began the study of chemistry?

A

Lavoisier and Priestly

4
Q

What are combinations of 2 or more atoms called?

A

Compounds

5
Q

How was the idea of a charge first discovered?

A

The ancient Greeks knew that amber, when rubbed with fur, could attract small particles

6
Q

What is the charge of an electron?

A

Negative

7
Q

What was the ‘Plum Pudding Model’?

A

The idea that electrons actually existed inside of the atom, like the bits of a plum pudding

8
Q

How was the Plum Pudding Model disproved?

A

Ernest Rutherford dots alpha particles at a gold sheet and found that they almost always passed through with only slight deflections.

9
Q

What was Rutherford’s model of the atom?

A

Tightly packed, positive nucleus with orbiting electrons

10
Q

What was the Bohr Atom?

A

Electrons orbited the nucleus at discrete orbits of fixed energy

11
Q

What happens when an electron changes orbit?

A

It either emits or takes in energy do make this shift

12
Q

How can light be characterised?

A

As discrete particles called photons

13
Q

How could a transition from one orbit to another be achieved according to Bohr?

A

The photon could cause the electron to transition to a higher orbit only if it has the exact energy equalled the difference in energy levels

14
Q

How are the chemical properties of an element determined?

A

Through the number and arrangement of the electrons

15
Q

What are inert gases and why are they unique?

A

They have a full outer shell of electrons and as such will not partake in reactions as much

16
Q

What is the net electrical charge gained or lost in a chemical reaction called?

A

an ion

17
Q

What is a covalent bond?

A

Where an atom shares electrons

18
Q

What is an ionic bond?

A

When a positive and negative compound’s charges attract and form a chemical compound

19
Q

Why is a positively ionised gas more opaque?

A

Because the free electrons interact with the light and scatter it

20
Q

What is an isotope?

A

Two atoms with the same number of protons but different number of protons

They are still the same element since the number of protons is the same

21
Q

How was radiation discovered?

A

Henri Becquerel left a uranium compound on top of some film and it left an image

22
Q

What are the 3 types of radiation

A

Alpha particles
Beta particles
Gamma rays

23
Q

What makes up an alpha particle?

A

2 protons, 2 neutrons

24
Q

What makes up a beta particle?

A

Electrons

25
Q

What makes a gamma ray?

A

Essentially rays of light with very high energy

26
Q

What happens when a nucleus emits an alpha particle?

A

It transmutes into another element which has 2 fewer protons

27
Q

What happens when a nucleus emits a beta particle?

A

It transmutes into an isotope of the same element, which has one more proton and one less neutron

28
Q

What is a half life?

A

When half the members of the original nuclei have decayed

29
Q

What is the significance of a half life?

A

It can be used to estimate the Galaxy’s age

30
Q

What is nuclear fission?

A

When a nucleus splits to form two lighter nuclei. This releases a lot of energy

31
Q

What is nuclear fusion?

A

2 nuclei combine to form a heavier element. This also releases a lot of energy

32
Q

What kind of nuclear reaction gives the Sun its shine?

A

nuclear fusion

33
Q

What are cosmic rays?

A

high-energy rays coming to Earth from space

34
Q

What is quantum mechanics?

A

The system of physical laws that governs the behaviour of elementary particles

35
Q

How does a particle spin?

A

Either in integer or half-integer values

36
Q

What is a boson?

A

A full spin of a particle

37
Q

What is a fermion?

A

A half spin of a particle

38
Q

What is the charge of an up spin?

A

positive

39
Q

What is the charge of a down spin?

A

Negative

40
Q

What is the primary duty of bosons?

A

To carry force and energy

41
Q

What is the primary duty of fermions?

A

To make up matter

42
Q

How are bosons grouped?

A

Arbitrarily

43
Q

What is the exclusion principle? (2)

A

It explains why only one of 2 electrons are able to occupy the closest orbital radius; one has spin up energy one has spin down energy

Fermions cannot interact with each there since they must have distinct quantum states

44
Q

What is an antiparticle?

A

Mirror image of the particle except it just has the opposite charge to the other

45
Q

What is the antiparticle to an electron called?

A

A positron

46
Q

What happens when a particle collides with its antiparticle?

A

Both are converted to pure energy in the form of gamma rays

47
Q

What is the antiparticle of a photon?

A

A photon is its own antiparticle

48
Q

What are the 4 fundamental forces of nature?

A
  • electromagnetic force
  • gravity
  • strong interaction
  • weak interaction
49
Q

What is strong interaction

A

the force that holds nucleons together

50
Q

What is weak interaction

A

force that mediates nuclear reactions such as fission and beta decay

51
Q

When do the 4 fundamental forces arise?

A

When there is an exchange of carrier bosons (gauge bosons)

52
Q

Why is gravity and electromagnetic force unlimited?

A

Their bosons are massless

53
Q

What is electromagnetic force?

A

The force that exists between charged particles

54
Q

What is ‘work’?

A

the exertion of a force to cause a displacement

55
Q

what is ‘energy’?

A

the capacity to do ‘work’

56
Q

what is heat?

A

the aggregate energy of the particles

57
Q

what is thermodynamics?

A

the study of energy in general, heat in particular

58
Q

what is temperature?

A

the mean random kinetic energy of th particles

59
Q

what is the first law of thermodynamics?

A

the law of conservation of energy

60
Q

what is the second law of thermodynamics?

A

in any process, the overall entropy increases or at best remains the same

61
Q

what is the 3rd law of thermodynamics?

A

absolute zero may never be attained, but only approached arbitrarily and closely

62
Q

what is the amplitude of a wave?

A

the wave’s maximum displacement

63
Q

what is the crest of a wave?

A

the highest point of the wave

64
Q

what is the trough of a wave?

A

the lowest point of a wave

65
Q

when does constructive interference occur

A

when 2 troughs or 2 crests meet

this causes a greater displacement than is present in either wave

66
Q

when does a destructive interference occur?

A

when a crest and a trough meet

this means that net displacement is reduced or even cancelled

67
Q

What is the Doppler effect?

A

The sound of something fast approaching has its pitch raised as it gets closer to you

68
Q

What is a blueshift (Doppler effect)

A

An approaching object shifts the light waves so that they bunch up and are thus shifted towards higher frequencies

69
Q

What is a redshift (Doppler effect)

A

a receding object shifts the waves so that they are of lower frequencies

70
Q

What can the Doppler effect tell us about stars, nebulae and nearby galaxies?

A

how fast the object is moving towards/away from the earth

71
Q

What can we conclude if there is a measure of a redshift and a blueshift?

A

the object is rotating

72
Q

What is the relationship of speeds of electromagnetic waves in a vacuum?

A

all of the waves travel at the same speed

73
Q

When does thermal radiation occur?

A

in any object with a temperature greater than absolute zero

74
Q

What was Planck’s breakthrough?

A

he made the assumption that radiation could only be absorbed or emitted in specific, discrete places

75
Q

How can we determine the mass of celestial objects?

A

By the gravitational force it exerts on other objects

76
Q

what are spiral galaxies?

A

great disks of stars

77
Q

what are elliptical galaxies?

A

stars clustered in elliptical pattern

78
Q

what are irregular galaxies?

A

stars in a random order

79
Q

What is a cluster of a cluster of galaxies called?

A

a supercluster