GC: n

CT: According to the theory quantum mechanics, an electron bound to an atom can not have any value of energy, rather it can only occupy certain states which correspond to certain energy levels. The formula defining the energy levels of a Hydrogen atom are given by the equation: E = -E0/n2, where E0 = 13.6 eV (1 eV = 1.602×10-19 Joules) and n = 1,2,3… and so on. The energy is expressed as a negative number because it takes that much energy to unbind (ionize) the electron from the nucleus. It is common convention to say an unbound electron has zero (binding) energy. Because an electron bound to an atom can only have certain energies the electron can only absorb photons of certain energies exactly matched to the energy difference, or “quantum leap”, between two energy states.
Because an electron bound to an atom can only have certain energies the electron can only absorb photons of certain energies.
When an electron absorbs a photon it gains the energy of the photon. Because an electron bound to an atom can only have certain energies the electron can only absorb photons of certain energies. For example an electron in the ground state has an energy of -13.6 eV. The second energy level is -3.4 eV. Thus it would take E2 − E1 = -3.4 eV − -13.6 eV = 10.2 eV to excite the electron from the ground state to the first excited state.
If a photon has more energy than the binding energy of the electron then the photon will free the electron from the atom – ionizing it. The ground state is the most bound state and therefore takes the most energy to ionize.

S: Astrounl – https://bit.ly/2hI0ai6 (last access: 14 December 2018).

N: 1. Coined 1891 by Irish physicist George J. Stoney (1826-1911) from “electric” + -on, as in “ion” (q.v.). Electron microscope (1932) translates German Elektronenmikroskop.

• Symbols: e or ß.

2. An elementary particle consisting of a charge of negative electricity equal to about 1.602 × 10−19 coulomb and having a mass when at rest of about 9.109 × 10−31 kilogram or about ¹/₁₈₃₆ that of a proton
3. Electrons have three fundamental properties: charge, mass, and spin. By definition, the electric charge on an electron is −1. The mass of an electron has been measured and found to be 9.109389 × 10−31 kilograms. Electrons also spin on their axes in much the same way that planets do. Spinning electrons, like any other moving electric charge, create a magnetic field around themselves. That magnetic field affects the way electrons arrange themselves in atoms and how they react with each other. The field is also responsible for the magnetic properties of materials.
4. The most accurate measurement yet of the shape of the electron has shown it to be almost perfectly spherical. The research, by a team at Imperial College London, is published in the latest edition of Nature journal. In their scientific paper, the researchers say the electron differs from being perfectly round by a minuscule amount.
5. The ordinary electrons of matter are negatively charged and are also known as negatrons.
(…) positively charged electrons also existent are called positrons.
6. electron: term standardized by ISO in 1997.

S: 1. OED – https://bit.ly/2EvymrA (last access: 14 December 2018); TERMIUM PLUS – https://bit.ly/2QWYpha (last access: 14 December 2018). 2. MW – https://bit.ly/2Gd9A0X (last access: 13 December 2018). 3. SC – https://bit.ly/2LdG2Py (last access: 13 December 2018). 4. BBC – https://bbc.in/2SMMC25 (last access: 13 December 2018). 5. GDT – https://bit.ly/2BhYr9o (last access: 14 December 2018). 6. TERMIUM PLUS – https://bit.ly/2QWYpha (last access: 14 December 2018).

SYN: negatron, negaton. (depending on context)

S: TERMIUM PLUS (last access: 14 December 2018)