انت هنا الان : شبكة جامعة بابل > موقع الكلية > نظام التعليم الالكتروني > مشاهدة المحاضرة

Chapter Five: Many electron atom

Share |
الكلية كلية التربية للعلوم الصرفة     القسم قسم الفيزياء     المرحلة 3
أستاذ المادة فؤاد عطية مجيد       14/12/2016 09:48:00
Chapter Five: Many electron atom
5.1 The Stern-Gerlach experiment and spin
Experiments in the early 1920s discovered a new aspect of nature and at the
same time found the simplest quantum system in existence. In the Stern-
Gerlach experiment, a beam of hot atoms is passed through a nonuniform
magnetic field. This field would interact with the magnetic dipole moment of
the atom, if any, and deflect it.

This experiment discovered two surprising things. The atoms
specifically, the unpaired outer electron did have a magnetic dipole
moment. In effect, in addition to being charged, electrons acted like tiny
bar magnets. They also, as it developed, have a tiny intrinsic amount of
angular momentum, . (This quantity is called spin, and all
known elementary particles have nonzero spin.) Electrons are called
spin-1/2 particles.
The second surprising thing was how much the path of the electrons was
deflected. If electrons were really bar magnets, they could be oriented in
any direction. The component oriented along the magnetic field gradient
(say the Z direction) would determine the force on the electron, and
hence how much it would be deflected.
If electrons were like ordinary magnets with random orientations, they
would show a continuous distribution of paths. The photographic plate
in the Stern-Gerlach experiment would have shown a continuous
distribution of impact positions


What was observed was quite different. The electrons were deflected
either up or down by a constant amount, in roughly equal numbers.
Apparently, the Z component of the electron’s spin is quantized: it can
take only one of two discrete values. We say that the spin is either up or
down in the Z direction

Quantum Numbers and Atomic Orbitals

From the solution of Schr?dinger equation for hydrogen atom in
spherical coordinates, we obtained a set of mathematical equations, called
wave functions, which describe the probability of finding electrons at certain
energy levels within an atom.
A wave function for an electron in an atom is called an atomic orbital; this
atomic orbital describes a region of space in which there is a high probability
of finding the electron. Energy changes within an atom are the result of an
electron changing from a wave pattern with one energy to a wave pattern with
a different energy (usually accompanied by the absorption or emission of a
photon of light).

المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
download lecture file topic