Exam 2: Nuclear Reaction Flashcards
Nucleons
Particles in the nucleus
Mass number
Total number of nucleons
Nuclide
Atom with specific number of protons and neutrons (think of an element but this only pertains to nuclear chemistry)
Why does radioactive decay occur?
Nuclides have unstable nuclei
What is the “parent” nuclide?
The nucleus that is undergoing radioactive decay
What is the “daughter” nuclide?
The new nucleus that is made
What happens when a nuclide decays?
It usually changes into a nuclide of a different element. It spontaneously emits radiation in which a particle or energy is emitted. The intensity of the radiation is not affected by temperature, pressure, or other physical and chemical conditions.
What are the three natural types of radioactive emission?
Alpha particles are identical to helium-4 nuclei. Beta particles are high-speed electrons. Gamma rays are very high-energy photons.
What happens during alpha decay?
The nucleus emits an alpha particle and it acquires two electrons from an atom(s) at the end of its parts to become a helium atom
What is an alpha particle?
Essentially a helium nucleus (two protons and two neutrons) which is very stable
What is transmutation?
The process of transforming one element to another
How far do alpha particles travel?
They do not travel far in the air before being absorbed
What are alpha particles used in?
They are used in smoke detectors (largest and least penetrating)
What is beta decay?
Involves the ejection of a beta particle from the nucleus
What happens to neutron during beta decay?
Neutron is converted to a proton, which remains in the nucleus, and a beta particle is expelled
What is a beta particle?
Like an electron
What is positron emission?
The emission of a beta(+) particle from the nucleus; has a +1 charge
What is a positron?
The antiparticle of the electron (anti-electron)
What happens to the proton during positron emission?
Proton in the nucleus is converted into a neutron and a positron is emitted
What is electron capture?
Occurs when an inner orbital electron is pulled into the nucleus
What is the result of an electron capture?
No particle emission, but atom changes (same result as positron emission)
What happens to proton during electron capture?
Proton combines with the electron to make a neutron
What are the particle changes of beta emission, positron emission, and electron capture?
Beta: neutron changing into a proton
Positron: proton changing into a neutron
Electron: proton changing into a neutron
Draw the particle changes of beta emission, positron emission, and electron capture.
See slide 24 of LEC 27
What is gamma radiation?
Involves the emission of electromagnetic energy (similar to light energy) from an atom’s nucleus, as the protons and neutrons become more tightly bound; high energy photons
What is true about emission during gamma decay?
No particles are emitted during gamma radiation, so gamma radiation does not itself cause the transmutation of atoms (gamma rays have no mass or charge)
What is true about the emission of gamma radiation?
Gamma radiation is often emitted during, and simultaneous to, alpha or beta radioactive decay
What is the common example of gamma radiation?
X-rays; emitted during the beta decay of cobalt-60
What are the characteristics of gamma rays?
Very penetrating; they can be most efficiently absorbed by a relatively think layer of high-density material such as lead
How do you balance a nuclear reaction?
Balance the total of all atomic numbers and total of all mass numbers for the products and reactants
In nuclear reactions, how are the rate of reactions affected?
They are normally not affected by temperature, pressure, and catalysts
What is the difference between chemical and nuclear reactions in terms of energy?
Chemical reactions absorb and release small amounts of energy while nuclear reactions absorb and release tremendous amounts of energy
What particles are involved in chemical or nuclear reactions?
In chemical reactions, only electrons are involved while protons, neutrons, electrons, and other elementary particles are involved in nuclear reactions
What happens during a nuclear reaction?
Elements (or isotopes of elements) are converted from one another
How are radioactive substances used?
Used as tracers (ex: blood flow or brain imaging); usually involves the formation of an image; administered to treat disease or provide pain relief
