Unit 7: Understanding the Quantum Atom and Nuclear Physics

Quantized Energy Levels

Discrete energy states that electrons occupy in an atom.

Ground State

The lowest possible energy level of an atom, represented by $n=1$.

Excited States

Energy levels higher than the ground state, represented by $n=2, 3, 4…$.

Ionization Energy

Energy required to remove an electron completely from an atom.

Photons

Particles of light that electrons interact with to change energy levels.

Absorption

When an electron absorbs a photon and jumps to a higher energy level.

Emission

When an electron falls to a lower energy level, releasing a photon.

Continuous Spectrum

An uninterrupted band of colors emitted by a hot, dense solid or gas.

Emission Spectrum

Individual bright lines on a dark background emitted by a hot, low-density gas.

Absorption Spectrum

A continuous spectrum with dark lines missing, caused by cool gas between the source and observer.

Strong Nuclear Force

An attractive and extremely strong force that binds nucleons in the nucleus together.

Alpha Decay

A decay mode that emits a helium nucleus, decreasing both mass and atomic number.

Beta-Minus Decay

A decay mode where a neutron becomes a proton and emits an electron, increasing atomic number.

Beta-Plus Decay

A decay mode where a proton becomes a neutron and emits a positron, decreasing atomic number.

Gamma Decay

A decay mode that emits high-energy photons without changing mass or atomic number.

Mass Number (A)

The total number of protons and neutrons in a nucleus.

Atomic Number (Z)

The number of protons in a nucleus, defining the element.

Neutron Number (N)

The number of neutrons in a nucleus, calculated as $A - Z$.

Mass Defect ($Delta m$)

The difference between the total mass of nucleons and the actual mass of the nucleus.

Binding Energy (BE)

The energy required to hold the nucleus together, related to mass defect.

E = mc^2

The equation illustrating that mass and energy are interchangeable.

Binding Energy Per Nucleon (BE/A)

Binding energy calculated for each nucleon, indicating stability of elements.

Fission

The process of heavy nuclei splitting into lighter ones, releasing energy.

Fusion

The process of light nuclei combining into heavier ones, releasing energy.

Planck's Constant (h)

$6.63 imes 10^{-34} ext{ J}ullet ext{s}$, a key constant in quantum mechanics.

Speed of Light (c)

$3.0 imes 10^{8} ext{ m/s}$, the speed at which light travels in a vacuum.

Conservation of Charge

The principle that electric charge must be conserved in nuclear reactions.

Joules vs. eV

Joules are a unit of energy used in physics, while electron-volts (eV) are often used in nuclear physics.