Chapter 9: Atomic and Nuclear Phenomina Flashcards

Question

What is the mass defect?

Answer 1

The mass defect is the difference in mass between what we would expect by taking the sum of all the masses of the protons and neutrons, and the actual mass of the nucleus. The mass defect is the mass that contributed to the binding energy of the nucleus.

Answer 2

The strong nuclear force is what attracts nucleons (protons and neutrons) together. The strong nuclear force only acts over extremely small distances (less than a few times the diameter of a nucleon. This means that nucleons need to get very close together in order for the strong nuclear force to hold them together.

Answer 3

Nucleons have to get very close to each other in order for the strong nuclear force to hold them together. The bonded system is at a lower energy level than the unbounded constituents, and the difference in energy must be radiated away in the form of heat or light or other em radiation before the mass defect becomes apparent. This energy is called the binding energy. The amount of mass that is transformed into the dissipated energy will be a measurable fraction of the initial total mass.

Answer 4

Iron has the highest binding energy per nucleon. This implies that iron contains the most stable nucleus. In general, intermediate sized nuclei are more stable than very large or very small nuclei.

Answer 5

The general trend is that intermediate sized nuclei are more stable than very large or very small nuclei.

Answer 6

Strong nuclear force, weak nuclear force, electrostatic forces, and gravitation.

Answer 7

The strong nuclear force is one of the four primary forces and provide provides the adhesive force between the nucleons (protons and neutrons) in the nucleus. Mass defect is the apparent loss of mass when nucleons come together, as some of the mass is converted into energy. That energy is called the binding energy.

Answer 8

Mass defect is related to the binding energy, such that there is a transformation of nuclear matter to energy with the result and loss of matter. They are related by the equation E=mcsquared.

Answer 9

Fusion occurs when small nuclei combine to form larger nucleus. For example. Stars power themselves by fusing four H nuclei to form one He nucleus. This energy that is produced accounts for the mass defect that arises from the formation of He nuclei from H nuclei. Fusion energy is directly related to mass defect; the energy released in a fusion reaction comes from the difference in mass between the initial nuclei and the resulting heavier nucleus, which is known as the "mass defect".

Answer 10

Fission is the process by which a large nucleus splits into smaller nuclei. Through absorption of a low energy neutron, fission can be induced in certain nuclei.

Answer 11

Radioactive decay is a naturally occurring spontaneous decay of certain nuclei accompanied by the emission of specific particles. 1. Integer arithmetic of particle and isotope species. 2. Radioactive half life problems. 3. The use of exponential decay curves and decay constants.

Answer 12

When balancing nuclear reactions, the sum of the atomic numbers and mas numbers must be the same on both sides of the equation. Start by balancing the number of protons (atomic numbers). Often times, wrong answer choices will simply have an error in the number of protons and can be eliminated before checking mass numbers.

Answer 13

The mass defect is the difference in mass between what we would expect by taking the sum of all the masses of the protons and neutrons, and the actual mass of the nucleus. The mass defect is the result of binding energy

Answer 14

Alpha decay is the emission of an alpha particle. An alpha particle is an He nucleus that contains no electrons. An He nucleus has 2 protons and 2 neutrons (a total of 4 nucleons). The notation for an alpha particle is in the image.

Answer 15

An alpha particle is a He nucleus with no electrons (2 protons, 2 neutrons, zero electrons). The charge of an alpha particle is +2e, positive two elementary charges.

Answer 16

Beta decay is the emission of a beta particle. A beta particle is an electron and is given by the symbol in the image. Beta particles are emitted from the nucleus when a neutron decays into a proton, creating a beta particle and an antineutrino.

Answer 17

In some cases of induced decay (positron emission), a positron is released, which has the mass of an electron but carries a positive charge.

Answer 18

A positron has the mass of an electron and carries a positive charge.

Answer 19

Both beta- and beta+ decay produce different elements. This is because the decay changes the number of protons, the defining feature of an element. Beta- decay, neutron is converted to a proton, emitting an electron. This adds a proton (higher atomic number) while maintaining mass number. Beta+ decay, proton is converted to a neutron, emitting a positron. This reduces the atomic number while maintaining the mass number.

Answer 20

Negative beta decay produces a negative beta particle, positive beta decay produces a positive beta particle.

Answer 21

Gamma decay is the emission of gamma rays. Gamma rays are high energy (high frequency) photons. They carry no charge and simply lower the energy of the parent nucleus without changing the mass number or the atomic number. High energy state of the parent nucleus may be represented by an asterisk in the balanced isotopic notation equation.

Answer 22

Refer to book if needed to wrap this up. This is an excellent way to solidify our understanding here.

Answer 23

Certain unstable radionuclides are capable of capturing an inner electron that combines with a proton to form a neutron, releasing a neutrino. The atomic number is mow Z-1, but the mass number remains the same as a proton is transformed to a neutron. Electron capture can be thought of as the reverse of beta- decay.

Answer 24

In radioactive particles, the half-life (T1/2) of the sample is the time it takes for half of the sample to decay. In each subsequent half life, one half of the remaining sample decays so that the remaining amount asymptotically approaches zero.

Answer 25

The decay constant is the probability that a radioactive atom will decay in a given amount of time.

Answer 26

The exponential decay equation tells us how the number of radioactive nuclei changes with time.

Answer 27

Around 7-8 half lives.

Answer 28

True. Both nuclear fusion and nuclear fusion reactions release energy. They may seem like inverses of each other, but they both release energy.

Answer 29

The portion remaining will never quite reach zero. However, for the theoretical consideration, all of a sample is considered to have decayed after 7 to 8 half lives.

Answer 30

Because gamma radiation produces electromagnetic radiation, rather than nuclear fragments, it can be detected on an atomic absorption spectrum.

Answer 31

First we solve for the energy of the photon (hf). Then we solve for maximum kinetic energy (hf-hfT). Once we have kinetic energy, we can solve for velocity (K=1/2mv^2….. v=(2k/m)^1/2)

Answer 32

First we solve for the energy of the photon, Kmax=hf-hfT. Second we solve for the frequency, E=hf. Then we solve for wavelength c=f(lambda)…. Wavelength=c/f. Careful with units and exponents. Area of misunderstanding on first try is highlighted in yellow.

Answer 33

First we need to convert electron volts to joules (conversion given in the question) Second, we need to solve for wavelength (wavelength=hc/E) The area outlined in yellow on the answer image demonstrates the need to make approximations to solve these problems. Use as much scratch paper as you need, you don’t have to do it all in your head.

Answer 34

First understand that the mass defect equals the mass expected minus the mass observed. Refer to a periodic table to get the atomic number of argon. Calculate the expected mass and then subtract the mass observed (mass observed is given in problem) This will give us the mass defect (m in amu) to plug into E equals MC squared.

Answer 35

We need to know the mass defect between the reactants and the products. Do this by adding the mass of the reactants and subtracting the mass of the products. This will give you an atomic mass unit to use to convert to MeV using the conversion given in the question.

Answer 36

The book just reasons this one out, and as did we when we first encountered this question. There’s an interesting example using mathematical way to reason through this problem in the image in black.

Answer 37

We recognized that lambda is the decay constant which is the change of n (number of nuclei not yet decayed) over change in time. The answer is negative lambda.

Answer 38

We reasoned through this well and came up with the correct answer.

Answer 39

In Alpha decay, an element loses two protons. In positron decay, a proton is converted into a neutron. Gamma decay has no impact on the atomic number of the nuclide. Therefore, two alpha decays and two positron decays will yield a daughter nuclide with six fewer protons than the parent nuclide.