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2006-11-09 21:20:53 · 12 answers · asked by Anonymous in Science & Mathematics Chemistry

12 answers

this guy explains it as easily as can be explained

http://www.newton.dep.anl.gov/askasci/chem99/chem99297.htm

2006-11-09 21:42:52 · answer #1 · answered by Anonymous · 0 0

In atomic physics, the spin quantum number is a quantum number that parametrizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle. The spin quantum number is the fourth of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter

An electron spin s = 1/2 is an intrinsic property of electrons. Electrons have intrinsic angular momentum characterized by quantum number 1/2.

The energy of any wave is the frequency multiplied by Planck's constant. This causes the wave to display particle-like packets of energy called quanta. To show each of the quantum numbers in the quantum state, the formulae for each quantum number include Planck's reduced constant which only allows particular or discrete or quantized energy levels. The reduced Planck's constant is used because in a wave, a cycle is defined by the return from a certain position to the same position such as from the top of one crest to the next crest. This actually is equivalent to a circle both having 360 degrees. There are 2 pi radians per cycle in a wave. Therefore, dividing h by 2π describes a constant that when multiplied by the frequency of a wave gives the energy of one cycle. When the subatomic particle the electron was being described by wavefunctions in Dirac's equation, it was found that the property of spin of all particles is a multiple of h-bar denoted by , that is, h (Planck's constant) divided by 2π. H-bar or has an even multiple for bosons and an odd multiple for fermions.

2006-11-10 03:21:44 · answer #2 · answered by Mysterious 3 · 0 0

Quantum Numbers Video

2017-01-14 08:48:52 · answer #3 · answered by ? 4 · 0 0

An electron within a subshell can have either one of two spins. But the electron does not spin in 1 direction throughout its life. At times, it has clockwise and at other times, anticlockwise spin. The average of these 2 states is 1/2. The + and - signs denote the direction of the spin-+ for clockwise, - for anticlockwise.

2006-11-09 21:41:55 · answer #4 · answered by abhishek 3 · 0 0

In atomic physics, the spin quantum number is a quantum number that parametrizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle. The spin quantum number is the fourth of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter s. There are a set of quantum numbers associated with the energy states of the atom. The four quantum numbers n, l, m, and s specify the complete and unique quantum state of a single electron in an atom called its wavefunction or orbital. The wavefunction of the Schrödinger wave equation reduces to the three equations that when solved lead to the first three quantum numbers. However, line emission spectra of some atoms when measured in an external magnetic field turned out to be more complicated than predicted by the first three quantum numbers. There needed to be a fourth quantum number that could properly predict spectra that matched the complexity found in nature so that this new quantum number had to behave as if it were also derived from the algebra of angular momentum vectors. A solution to this problem was suggested in early 1925 by George Uhlenbeck and Samuel Goudsmit, students of Paul Ehrenfest (who rejected the idea), and independently by Ralph Kronig, one of Landé's assistants, by introducing the idea of the self-rotation of the electron which would naturally be an angular momentum vector. An electron spin s = 1/2 is an intrinsic property of electrons. Electrons have intrinsic angular momentum characterized by quantum number 1/2. The energy of any wave is the frequency multiplied by Planck's constant. This causes the wave to display particle-like packets of energy called quanta. To show each of the quantum numbers in the quantum state, the formulae for each quantum number include Planck's reduced constant which only allows particular or discrete or quantized energy levels. The reduced Planck's constant is used because in a wave, a cycle is defined by the return from a certain position to the same position such as from the top of one crest to the next crest. This actually is equivalent to a circle both having 360 degrees. There are 2 pi radians per cycle in a wave. Therefore, dividing h by 2π describes a constant that when multiplied by the frequency of a wave gives the energy of one cycle. When the subatomic particle the electron was being described by wavefunctions in Dirac's equation, it was found that the property of spin of all particles is a multiple of h-bar denoted by , that is, h (Planck's constant) divided by 2π. H-bar or has an even multiple for bosons and an odd multiple for fermions. In the electron, the two different spin orientations are sometimes called "spin-up" or "spin-down". The spin property of an electron would classically give rise to magnetic moment which was a requisite for the fourth quantum number. When atoms have even numbers of electrons the spin of each electron in each orbital has opposing orientation in different directions. However, many atoms have an odd number of electrons or an arrangement of electrons in which the number of "spin-up" and "spin-down" orientations are not the same. These atoms or electrons are said to have unpaired spins which are detected in electron spin resonance.

2016-03-28 01:12:42 · answer #5 · answered by Anonymous · 0 0

The spin quantum number does not come in the solutions of schrodringer but it was added after wards due to difficulty of spin.The spin of an electron can be in only two direction(relatively opposite).Thus it can have only two values for spin quantum number +-1/2.

2006-11-09 21:44:02 · answer #6 · answered by Neo 2 · 0 0

now when the pairing occurs in the shell what happens is that if the electron has only -1/2 spin the the total spin will be -1,unstable.
electron has only +1/2 spin then the total spin will be +1, unstable;
so to make the electron pair stable they gave the value as +/- 1/2

2006-11-15 00:48:24 · answer #7 · answered by santhosh 1 · 0 0

This is actually pretty arbitrary and driven by the mathematics.

Quantum Mechanics is highly mathematical (in fact it is entirely differential operators) as opposed to a real tangible kind of understanding. The quantity of "1/2" is really very arbitrary and arises purely because -1/2 and +1/2 are negatives of each other and are exactly "1" apart. Quantum mathematics, as you may know, involves a lot of "+1" mathematics (because quanta are individual units), so having two opposite number which are exactly 1 apart is very useful.

2006-11-09 21:43:47 · answer #8 · answered by Stuart T 3 · 0 0

In atomic physics, the spin quantum number is a quantum number that parametrizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle. The spin quantum number is the fourth of a set of quantum numbers (the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter s.
for details
http://chemistry.about.com/library/glossary/bldef853.htm
http://en.wikipedia.org/wiki/Spin_quantum_number

2006-11-09 21:44:16 · answer #9 · answered by Anonymous · 0 1

b'coz an electron can spin in two directions i.e. clock wise and anti clock wise.
+1/2 denotes anticlock direction &-1/2 denotes clockwise direction

2006-11-09 22:17:11 · answer #10 · answered by kingkhanistheeebest 1 · 0 0

It denotes clockwise or anticlockwise rotation of an electron.

2006-11-10 20:48:21 · answer #11 · answered by vishnu k 2 · 0 0

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