Question | Answer |
Fluorescence | The phenomenon observed when an atom is excited by UV light and the electrons return to the ground state in two or more steps, emitting photons of lower frequency (often in the visible light spectrum) at each step. |
Photoelectric Effect | The phenomenon observed when light of a certain frequency is incident on a sheet of metal and causes it to emit an electron. |
Work Function | The minimum amount of photon energy required to emit an electron from a metal. This quantity, denoted by W, is used to calculate the residual kinetic energy of an electron emitted by a metal, given by KE = hf - W, where hf is the energy of a photon. |
Alpha Decay | Nuclear reaction in which in which an α-particle (two protons and two neutrons, He) is emitted. |
Beta Decay | Nuclear reaction in which a β-particle (e-) is emitted. |
Binding Energy | The energy that holds the protons and neurons together in the nucleus, defined by the equation E = mc^2, where m is the mass defect and c is the speed of light in a vacuum. |
Electron Capture | A radioactive process in which a nucleus captures an inner-shell electron that combines with a proton to form a neutron. As a result, the atomic number decreases by 1, but the atomic mass remains the same. |
Exponential Decay | A decrease in the amount of substance N, given by the equation: N = N0 x e^-λt. |
Fission | The nuclear reaction in which a large nucleus slits up into smaller nuclei. |
Fusion | The nuclear reaction in which two or more small nuclei combine to form a larger nucleus. |
Gamma Decay | The atomic emission of high energy photons, also known as γ-particles. |
Half-Life | The amount of time it takes for one-half of a radioactive sample to decay, given by the equation T1/2 = ln2/λ, where λ is a decay constant. |
Mass Defect | The difference between an atom's atomic mass and the sum of its protons and neutrons. |
Positron | An anti-electron, denoted β+ or e+, emitted in a nuclear reaction. |