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G9 + 10 physics > Unit 5 - Nuclear physics > Flashcards

Unit 5 - Nuclear physics Flashcards

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1
Q

What is a Cathode Ray Tube

A

Spits out electrons

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2
Q

Alpha particles

A

Positively charged particle that consists of 3 protons and 2 neutrons bound together

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3
Q

Who revealed the structure of atom with his gold foil experiment and what exactly was the experiment

A

Rutherford

A thing beam of alpha particles was made to strike against a gold foil and he noticed that some particles faced larger deviation from their original line of motion

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4
Q

Why did rutherford use gold for his experiment to discover structure of atom

A

Extremely malleable and ductile and the effect is more permanent on gold

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5
Q

conclusions from rutherford’s experiment

A

Most of the space in an atom is empty
The entire +ve charge of the atom is placed in the centre in the nucleus
The mass of an atom is also concentrated in the centre
Electrons orbit around the nucleus in a circular order

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6
Q

Atomic number and what is represented with?

A

The number of protons present within the nucleus of an atom.

Rep using Z

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7
Q

Neutron number and what is represented with?

A

Total number of neutrons present in the nucleus

Rep using N

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8
Q

Mass no. and what is represented with?

A

Total number of nucleons (protons + neutrons) present within the nucleus

Rep using A

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9
Q

Relationship between mass no, atomic number, neutron number

A

A = Z + N

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10
Q

Anti protons

A

Subatomic particle that is the anti matter counter part of a proton and has the same mass as protons. Negatively charged

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11
Q

Isotopes

A

Nuclei of the same element having same atomic number but different mass number. They have the same number of protons but different number of neutrons

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12
Q

Thermal Neutron

A

A neutron with very less energy and has gained it through heating it

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13
Q

Specialty of Uranium in terms of its uniqueness

A

the only naturally occurring radioactive element

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14
Q

Why are nuclei also unstable like atoms

A

Because there are multiple positively charged protons repelling each other, hence there is a very strong unstable repulsive force present within the nucleus of an atom

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15
Q

What takes place in a nucleus to give it 1000 N force

A

Protons repel each other, and due to the presence of a strong nuclear force they are held in place as well

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16
Q

Strong Nuclear Force

A

Force present within the nucleus
Attracts protons and neutrons
Responsible for protons not scattering

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17
Q

Relationship between strong nuclear force and repulsive force in a nucleus

A

Both are present and are as strong as they should be, however, dominating the repulsive force is the nuclear force

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18
Q

Radioactivity

A

The process in which an unstable nucleus undergoes to attain stability and release energy

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19
Q

Alpha Decay

A

Type of radioactive decay where an unstable nucleus decays to give out a more stable nucleus with -4 in mass number and -2 in atomic number alongside an Helium atom with 4 mass number and 2 atomic number

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20
Q

Beta Decay

A

Type of radioactive decay where an unstable nucleus decays to give out a more stable nucleus with a +1 in atomic number, -1 in neutron number while the mass number remains the same. It also emits a an beta minus particle with an anti-neutrino particle

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21
Q

Why is the mass number same in beta decay

A

Because one proton is added and one neutron is removed

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22
Q

Why is there one neutron less in beta decay in the daughter nucleus

A

Because one neutron decays to give out a proton, beta minus particle and anti neutrino

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23
Q

Beta minus particle atomic and mass number

A

Mass number = 0
Atomic number = -1

24
Q

Anti neutrino represnetation

A

Mass number = 0
Atomic number = 0
Written as a V with a bar on top ( ̅ν)

25
Q

Gamma Decay

A

A type of radioactive decay which generally happens after an alpha or beta decay (but can occur on its own as well), in which a unstable nucleus decays to give the nucleus (same isotope) but with an neutrino particle as well

26
Q

Neutrino particle representaion

A

Rep using V
Mass number = 0
Atomic number = 0

27
Q

How to symbolize less stable nucleus in gamma decay

A

By putting an asterisk sign (*)

28
Q

Law of radioactive decay

A

The number of unstable nuclei undergoing a decay per unit time is directly proportional to the number of undecayed nuclei

29
Q

How does the graph of law of radioactive decay look like

A

Exponentially decaying asymptote curve

30
Q

Formula for law of radioactive decay and significance of negative sign

A

ΔN/Δt ∝ -N

N = number of undecayed nuclei

The negative sign is used to indicate that the number of undecayed nuclei will decrease over time

31
Q

Properties of Radioactivity

A

1) It is spontaneous reaction
2) It is a random process

32
Q

Half Life

A

Time elapsed for half of the unstable nuclei to undergo decay

Represented using T_1/2

33
Q

What to do if you get decimal nuclei while half life-ing a set number of nuclei

A

Round the nuclei to one whole number below as decimal nuclei cant exist

34
Q

Formula for number of unstable nuclei after t units of time has elapsed

A

N = (1/2)^(t/half life) * N_0

N_0 = number of initial unstable nuclei

35
Q

Factors affecting number of undecayed nuclei

A

Initial number of undecayed nuclei (Higher the number of N_0, higher the rate of reaction)
Type of isotope (basically half life)

36
Q

Is Fission and Fusion spontaneous

A

No, requires intervention

37
Q

which isotope can be subjected to Fission

A

Uranium-235

38
Q

Fission

A

One big unstable nucleus breaks down into 2 smaller nuclei

39
Q

How does fission happen

A

A neutron is shot into U-235 with that much energy so that it penetrates the nucleus and STAYS THERE. This causes U-235 to become U-236 and then it undergoes fission to give out 2 more stable nuclei (generally Barium and Krypton) with neutrons.

40
Q

Can the neutrons given out after fission be used directly?

A

No, their energy is too high and we need to bring it down using a Moderator

41
Q

Moderator in Fission/Fusion

A

Substance used to bring down the energy of neutrons given out in the fission reaction so that they can be re-used. Generally the material used is Heavy Water

42
Q

Chain Reaction

A

Multiple fissions taking place one after the other and reusing the neutrons given out to create high amounts of energy.

43
Q

Uncontrolled Chain reaction

A

High amount of energy is produced in short period of time with a huge number of uncontrolled fissions. With each fission occurring, the neutrons produced add more fissions and hence increases exponentially. Used in Atom Bomb

44
Q

Controlled chain reaction

A

Happens if you are able to control the energy given out using Control rods

45
Q

What are control rods made of and why

A

Cadmium, because they can absorb neutrons without undergoing fission. Control rods also allow for the energy produced to be used efficiently

46
Q

Fusion

A

2 or more smaller nuclei combine together to form a bigger more stable nuclei

47
Q

Why cant fusion take place without fission on earth

A

Because 2 positively charged neutrons are trying to fuse together, we need a great amount of energy to outweigh the repulsive force and hence it required a very high temperature

48
Q

Temperature required for fusion to take place

A

10^7 Kelvin

49
Q

Which releases more energy, fusion or fission

A

Fusion

50
Q

Is mass conserved in fission/fussion

A

No, mass of reactants is more than mass of products and the mass lost is given out in the form of energy

51
Q

Bomb made with Fusion is known as

A

Hydrogen bomb, required an atomic bomb first to achieve 10^7 K temp and then only will an Hydrogen bomb work

52
Q

Which is more destructive and why, hydrogen bomb or atomic bomb

A

Hydrogen bomb, as energy release is more

53
Q

Real life applications of radio activity

A

Medical - X rays
Determining age of fossils
Detection of leakages

54
Q

Harmful effects of radio activity

A

Excessive exposure to humans degrades our health
Radio active waste is harmful to nature as it can contaminate water/soil/air

55
Q

Is fission better or fusion

A

Fusion is better as produces more energy, doesn’t produce long term radioactivity and has unlimited fuel supply. Fusion also produces more stable nuclei than fission

G9 + 10 physics (6 decks)

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