The Elements. Spectra Part II. The Nucleus. The Nucleus contains positively charged Protons and neutral Neutrons; almost all of the Atom’s mass. The number of protons determines the element. The Electrons.
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The Nucleus contains positively chargedProtons and neutral Neutrons; almost all of the Atom’s mass.
The number of protons determines the element.
Electrons can only orbit the nucleus in certain orbits.
n =1First orbital: Ground State)
The Electron prefers the Ground State
Ground State - Lowest energy state
For an electron to move to a higher orbit, it must gain energy E3 - E2
For the electron to move to a lower orbit, it must lose energy of the correct amount
For convenience, the energy levels (orbits) of an atom are represented by horizontal lines. Energy increases as you move upward in the diagram.
All Balmer lines star or end with the second level (n=2)
When an electron jumps from a higher to a lower energy orbital, a single photon is emitted with exactly the energy difference between orbitals. No more, no less.
An electron absorbs a photon with exactly the energy needed to jump from a lower to a higher orbital. No more, no less.
All stars are made of roughly 75% Hydrogen, 20% Helium, and 5% everything else.
Different absorption line spectra are not due to different chemical composition, but rather the effect of different surface temperatures.
Hydrogen lines are absent in the hotteststarsbecause,photons ionize electrons.
They are also absent in the coolest stars because, photons don’t have enough energy to move the electrons from n=2 to higher energy levels.
Molecules can complicate Spectra , because molecules can:
If there are magnetic fields present, the atomic energy levels are split into a larger number of levels and the spectral lines are also split. This splitting is called the Zeeman Effect.
The Zeeman Effect
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NASA, JPL, OSHO
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