Energy can only be emitted in definite amounts or quanta. Energy is quantized or restrict to specific levels, like climbing a ladder, one rung at a time.

Light behaves like a particle, called photon. A photon can discharge an electron from an atom if it collides with a greater energy than the electrostatic attraction.

The electrons travel around the nucleus of an atom in distinct circular orbits, or shells. The model is also referred to as the planetary model of an atom.

Matter, and light, have both wave and particle properties. The wave-particle duality is the start of quantum mechanics.

Two or more identical particles cannot simultaneously occupy the same quantum state. In an atom, two electrons cannot be at the same time in the same state or configuration.

This equation describes the energy and position of an electron in space and time, which describes how the quantum state of a physical system changes over time.

One cannot simultaneously know the exact position and momentum of a particle. With an image of a rollercoaster car, we would only be able to precisely calculate its speed or its location.

The Dirac equation for an electron moving in an arbitrary electromagnetic field explaines the origin of electron spin and predicts the existence of antimatter.

This method describes the behaviour of π-electrons in unsaturated molecules, particularly in aromatic compounds.

Bonded nuclei maintain an optimal distance (the bond distance) balancing attractive and repulsive effects explained using the principles of quantum mechanics.

To find the probability that a particle (a photon or an electron) at point A ends up at point B at some later time, one must consider all possible paths it can take.

DFT simplifies the complex problem of electron interactions in many-body systems, using the electron density to investigate the electronic structure of matter.