half-life Flashcards
define isotope
Isotopes are atoms of the same element that have the same number of protons (atomic number) but different numbers of neutrons. This means isotopes have different mass numbers, but their chemical properties are generally similar.
example of an isotope
Carbon-12 and Carbon-14 are isotopes of carbon. Both have 6 protons but differ in the number of neutrons.
define mass number
The mass number is the total number of protons and neutrons in the nucleus of an atom. It’s what gives an atom its “weight.”
example of mass number
For Uranium-238, the mass number is 238 (92 protons + 146 neutrons).
define atomic number
The atomic number is the number of protons in the nucleus of an atom. It determines the element’s identity and its position on the periodic table.
example of atomic number
Hydrogen has an atomic number of 1 because it has 1 proton.
define alpha decay
A type of radioactive decay where the nucleus emits an alpha particle (consisting of 2 protons and 2 neutrons). This reduces the atom’s atomic number by 2 and its mass number by 4.
example of alpha decay
Uranium-238 decays into Thorium-234 via alpha decay.
define beta decay
A type of radioactive decay where a beta particle (electron or positron) is emitted. In beta-minus decay, a neutron transforms into a proton, increasing the atomic number by 1. In beta-plus decay, a proton transforms into a neutron, decreasing the atomic number by 1. The mass number remains unchanged.
example of beta decay
Thorium-234 undergoes beta decay to produce Protactinium-234
what is a radioisotope an how does it decay
A radioisotope decays and changes to a different element at a constant rate. The rate is measured in a unit called the half-life. This is the length of time it takes for half of a given amount of the radioisotope to decay.
define radionuclide
A radionuclide is an atom that has an unstable nucleus and undergoes radioactive decay. In the process, it emits radiation (such as alpha particles, beta particles, or gamma rays) to become more stable.
what is an unstable atom called
radioisotope
how do radioisotopes become more stable
Radioisotopes become more stable by giving out nuclear radiation
what is the common defining feature of radioisotopes
Every radioisotope has its own half life
what can the half-life be used for
We can use the half-life to predict the amount of atoms in the sample after a certain amount of time
what is the defining feature of radioactive decay
Radioactive decay is random and spontaneous
what is half-life
Half-life is the time it takes for the number of nuclei in a sample to half
what can half-life be used for
Half-life can be used to predict how many nuclei will be left after a certain amount of time
how can the half life of an atom be determined
from a decay graph
define parent isotope
This is the original unstable atom. It undergoes radioactive decay, trying to become more stable. Think of it like the “parent” starting the process.
define daughter isotope
This is the product formed after the parent isotope decays. It’s the “child” isotope that comes out of the transformation. Sometimes, the daughter isotope is stable, but other times it might also decay further into another daughter isotope.
