Structure of Atom Test - 5

In 1920, Otto Stern and Walter Gerlach designed an experiment, which unintentionally led to the discovery that electrons have their own individual, continuous spin even as they move along their orbital of an atom. The experiment mentioned above by Otto Stern and Walter Gerlach was done with silver which was put in an oven and vaporized. The result was that silver atoms formed a beam that passed through a magnetic field in which it split in two.

The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.

quantum mechanics, science dealing with the behaviour of matter and light on the atomic and subatomic scale. It attempts to describe and account for the properties of molecules and atoms and their constituents—electrons, protons, neutrons, and other more esoteric particles such as quarks and gluons. These properties include the interactions of the particles with one another and with electromagnetic radiation (i.e., light, X-rays, and gamma rays).

The effect of Heisenberg uncertainty principle is significant only for motion of microscopic objects, it is negligible in case of macroscopic objects. For example, we apply the concept of uncertainty to an object of mass 1 milligram.



The value of Δx Δv_x is very small and insignificant in this case. Therefore, when we deal with heavier objects the associated uncertainties have no real consequences and can be neglected.

Quantum numbers designate specific shells, subshells, orbitals, and spins of electrons. This means that they describe completely the characteristics of an electron in an atom, i.e., they describe each unique solution to the Schrödinger equation, or the wave function, of electrons in an atom.

There are a total of four quantum numbers: the principal quantum number (n), the orbital angular momentum quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number (ms). The principal quantum number, nn , describes the energy of an electron and the most probable distance of the electron from the nucleus. In other words, it refers to the size of the orbital and the energy level an electron is placed in. The number of subshells, or ll , describes the shape of the orbital. It can also be used to determine the number of angular nodes.

The magnetic quantum number, ml, describes the energy levels in a subshell, and ms refers to the spin on the electron, which can either be up or down.

n (Principal quantum number) value tell about the shell to which the electro belong,   Ex,If  n=1 electron belongs to first shell (K) around the nucleus

l (Azimuthal quantum number) tell about angular momentum, and  shape of the orbitals, and it designates the subshells to which the 

electron belongs to. For a given value of  'n', ' l' can have value ranging from  0  to  n-1. Ex, If n=2 then , the value of 'l' will be 0 and 1  (0 to n-1)

ml ( Magnetic orbital quantum number)  determines the number of preferred orientations of the orbitals in the subshell, which are defined by given   'l' value. ex if 'l'= 2 then ml =  2l+1 =2 × 2 + 1= 5 m value ie.,  m = +2,+1,0,-2,-1

The Aufbau Principle states that in the ground state of an atom, an electron enters the orbital with lowest energy first and subsequent electrons are fed in the order of increasing energies. The word 'aufbau' in German means 'building up'. Here, it refers to the filling up of orbitals with electrons.

Probability density of finding an electron at a point with in an atom, it is posible to predict region around the nucleus where electron can most probably be found.

ψ has no physical significance while ψ² represnts the probability density of finding an electron.

Shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces of the electrons on the nucleus. It is also referred to as the screening effect (or) atomic shielding.

Daltons theory said atom is indivisible in nature so it doesnot explain the existence of subatomic particles.

The indivisibility of an atom was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. However an atom is the smallest particle that takes part in chemical reactions.