Question

DEFINE THE FOLLOWING A) NODE b) electron density c) heinsenberg uncertainty principle d) pauli exclusion principle

Answer 1

Electron density is the measure of the probability of an electron being present at a specific location.

In quantum mechanics, the uncertainty principle, also known as Heisenberg's uncertainty principle, is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known simultaneously.

Introduced first in 1927, by the German physicist Werner Heisenberg, it states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.The formal inequality relating the standard deviation of position σ_x and the standard deviation of momentum σ_p was derived by Earle Hesse Kennard later that year and by Hermann Weyl in 1928:

(ħ is the reduced Planck constant, h / 2π).

The Pauli exclusion principle is the quantum mechanical principle that states that two identical fermions (particles with half-integer spin) cannot occupy the same quantum state simultaneously. In the case of electrons, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum numbers: n, the principal quantum number, ℓ, the angular momentum quantum number, m_ℓ, the magnetic quantum number, and m_s, the spin quantum number. For two electrons residing in the same orbital, n, ℓ, and m_ℓ are the same, so m_s, the spin, must be different, and thus the electrons have opposite half-integer spins, 1/2 and -1/2. This principle was formulated by Austrian physicist Wolfgang Pauli in 1925