Atomic Physics Flashcards
All atoms are naturally ______ and contain _______
neutral, electrons
Alpha particles definition
relatively large, positively charged particles that are emitted by certain radioactive elements. Helium nuclei, consisting of two protons and two neutrons.
The ______________ experiment established that the atom has a nucleus
Rutherford alpha-scattering
Excited, low pressure gases each give off their own ______ ______
bright line, spectrum
“Ground state energy” definition
the lowest energy orbit of an electron around a nucleus. Occurs closest to the nucleus (smallest radius).
Bohr’s model of the atom places electrons in selected, ______ orbits around the nucleus
quantized
Electron energy levels are measured in _____________, a small unit of energy
electron-volts (eV)
Rules for an electron changing energy levels (gain):
the electron must absorb EXACTLY enough energy to reach a higher energy level–no more, no less– it jumps up to that level. If it absorbs enough energy, it can jump to a level two, three, or more levels above it. If the energy offered to the electron is not exactly enough to raise it to a higher level, the electron will ignore the energy and let it pass.
ONLY exception to the rules for an electron changing energy levels (gain):
If an electron absorbs energy equal to or greater than the amount needed to lift it to the highest energy level of its atom, it can escape from the atom altogether, and any excess energy is converted to kinetic energy
Rules for an electron changing energy levels (loss):
When an electron is in a higher energy level, it can jump down to a lower energy level by releasing energy in the form of a photon of light. The energy of the emitted photon is exactly equal to the difference between the energy levels the electron moves between. As when it absorbs energy, an electron can jump down one, two, or more levels depending on how much energy it releases.
State each scientist’s model of the atom: Thomson, Rutherford, Bohr
Plumpudding model, Planetary model, Quantized energy level model
An emission spectrum is produced when:
electrons in an excited gas jump down to a lower energy level and release photons
