Chapter 30 - Nuclear Physics and Radioactivity

N0

Where ________ is the original amount of radioactive nuclei, e is the natural exponential, k is a constant, and t is time passed thus the number of radioactive nuclei decreases exponentially with time.

ΔN

Where ________ is the number of decays, Δt is the time interval, the- means N is decreasing, N is the number of radioactive nuclei in the sample, and λ is the decay constant • Decay Constant- A value that varies for different isotopes Exponential Decay • Radioactive Decay Law- Solving for N gives.

Nuclides

Used to refer to different nuclei

Atomic Number

The number of protons in a nucleus, denoted by Z

Atomic Mass Number

The number of protons plus the number of neutrons in an atom, denoted by A

Isotope

Nuclei that share the same atomic number but different mass numbers

Natural Abundance

The percentage of a naturally occurring isotope of a certain element

Unified Atomic Mass Units

A unit of mass used to specify the masses of nuclei

Nuclear Spin

A quantum number of nuclei that can be either an integer or a half integer

Total Binding Energy

The difference in mass between a nuclei’s true mass and the sum of its nucleons, represents the energy that must be put into a nucleus to separate it into its components

Binding Energy per Nucleon

Defined as the total binding energy divided by A

Strong Nuclear Force

The force that holds nucleons together an opposes the electrostatic repulsion between protons

Weak Nuclear Force

A weaker type of nuclear force that is only known about because of its presence in certain types of nuclear decay

Radioactivity

The phenomenon of certain materials producing radiation that are not x-rays or weaker

Radioisotope

A radioactive isotope of a certain element

Transmutation

The conversion from one element to another

Disintegration Energy

Total energy released when a alpha decay occurs

Smoke Detectors

Devices that use alpha decay from Americium to ionize nitrogen and oxygen in the surrounding air, allowing current to flow, when smoke is present the smoke particles absorb the radiation instead and stop the current flow, setting off the alarm

Electron Capture

Occurs when a nucleus absorbs one of its orbiting electrons

Gamma Ray

An extremely high-energy photon, come from decaying nuclei

Internal Conversion

The process through which an excited nucleus returns to its ground state not by releasing a gamma ray, but by releasing an orbital with the same kinetic energy a gamma ray would

The Law of Conversion of Nucleon Number

States that the total number of nucleons, remains constant in any process

Decay Constant

A value that varies for different isotopes

Radioactive Decay Law

Used to calculate decay rate of radioactivity

Half-Life

Defined as the amount time it takes half the original amount of parent isotope to decay

Decay Series

A chain of successive radioactive decays where daughter isotopes lead to other daughter isotopes

Radioactive Dating

A technique used to determine the age of a sample by comparing the presence of radioactive isotopes before and after

Geiger Counter

A device consisting of a metal tube filled with a gas and a wire kept at a high positive voltage

Scintillation Counter

Uses a scintillator or phosphor whose particles are easily excited and emit light when they return to ground state, they detect the light released

Photomultiplier Tube

Converts the light emitted by a scintillator to an electric signal

Semiconductor Detector

Uses a reverse-biased pn junction diode to detect a charged particle when it excites electrons into the conduction band

Silicon Wafer Semiconductors

Used to visualize charged particles, have pixels etched onto theirsurfaces that each give particle position information

Cloud Chamber

Works bu super cooling a gas, tiny droplets form around charged particles and the reflection of light is used to detect the movement of particles

Bubble Chamber

Similar to a cloud chamber, super heats a liquid and bubble of vapor form around charged particles

Multi wire Chamber

Consists of many wires in a gas, some of which are charged. Charged particles excite molecules in the gas and ionize them, causing them to be attracted by the charged wires and sending a pulse once they come in contact