More Lessons for High School Physics
A series of free Online High School Physics Video Lessons.
In this lesson we will learn
- Beta Decay
- Electron Capture
- Radioactive Isotopes
- Carbon Dating
There are two types of beta decay: beta-plus decay and beta-minus decay. In beta plus decay the nucleus emits a positron (a positively charged electron) and a neutrino (a proton that changed into a neutron), resulting in the element before it on the periodic table. In beta-minus decay, the nucleus emits an electron and an antineutrino (a neutron that changed to a proton), resulting in the element after it on the periodic table.
Understanding the two types of beta-decay of radioactive substances.
Sometimes known as Beta minus decay or Beta emission, this process is related to Positron decay. An unstable atom takes a neutron and turns it into a proton, creating a high-energy electron known as a Beta particle. This makes the atom more stable. In this video, we learn the basics of Beta decay, and then write nuclear equations.
Electron Capture is a type of decay in which the nucleus of an atom draws in an innershell electron. It occurs when neutrons/proton is below the band of stability (too many protons) but there is not enough energy to emit a positron.
How unstable nuclei capture electrons?
We introduce electron capture and do some practice example problems. Electron capture is a nuclear decay process. It turns a proton into a neutron, lowering the atomic number, but keeping the mass number the same. It creates gamma rays in the process. Electron capture is similar to alpha decay, beta decay, and positron decay.
Radioactive isotopes have unstable ratios of protons to neutrons in their atomic nuclei. An isotope is an element with a varying numbers of neutrons. Radioactive isotopes become more stable through nuclear reactions including alpha decay and beta decay. One example of a radioactive isotope is Carbon-14 which is used for carbon dating.
The effects of radioactive isotopes.
Alpha particles, beta particles and gamma rays.
Alpha particles are helium nuclei with a +2 charge, Big, heavy and slow moving, don't penetrate into materials, Very ionising, Blocked by paper.
Beta particles are high-energy electrons with a -1 charge; Quite small, move quite fast, Penetrate materials moderately, Ionise moderately, for every beta particle emitted, a neutron turns into a proton in the nucleus, some are blocked by thin Aluminium, but certainly blocked by tissue.
Gamma rays are electromagnetic waves with shorter wavelength (higher frequency) than x-rays, Opposite to alpha, Penetrate materials well, Weakly ionising, blocked by 7 cm of lead.
Half-life is the concept of time required for half of radioactive isotope's nuclei to decay. The amount remaining is calculated as the (initial amount) (1/2) (# of 1/2 lives)n
in which the number of 1/2 lives is equal to the time elapsed over the length of half-life.
Understanding the half-life of a radioactive substance.
Nuclear half life is the time that it takes for one half of a radioactive sample to decay. In this video, we will learn the basics of nuclear half life, and examine graphs and practice problems.
Carbon dating uses an unstable isotope of carbon to find the date of dead substances. This isotope Carbon-14 has a half life of 5,700 years. The ratio of Carbon-14 remaining indicates the times since the death of a living substance. Carbon-14 only works for things between 3 and 40 thousand years old.
How to solve problems using carbon dating.
Carbon Dating is explained and an example problem worked out.
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