Quantum theory Flashcards
(32 cards)
quantum mechanics definition
which is the theory neededto describe the behaviour of individual atoms, molecules and the electrons theycontain.
Atomic orbitals
follows the laws of quantum mechanics
quantized
energy cannot take any level. it is restricted to a certain set of values, usually called energy levels,
location and quantum mechanics
we so not know precisely where a particle is located – all we can do is give the probability that a particle will be at a particular position. Different positions (coordinates)have different probabilities associated with them, so as a result it appears that the particle is ‘spread out’ over a region of space,
wave fucntion
variable quantity that mathematically describes the wave characteristics of a particle
wave function symbol
psi.
atomic spectra
the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom.
The principal quantum number,
n, describes the energy of an electron and the most probable distance of the electron from the nucleus.
n =1,2,3,4
The azimuthal number L
The azimuthal quantum number describes the shape of a given orbital.
the symbol ‘l’.
A value of the azimuthal quantum number can indicate either an s, p, d, or f subshell which vary in shape.
n–1
§ Magnetic quantum number
how many orbitals are there in a type.
it describes a specific orbital amongst. a particular set.
n–1
l 0=1 0
l 1=3 -1, 0, 1
l 2= 5 ………
l 3 = 7…………………
Spin quantum number
0.5/-0.5
Spin quantum number
0.5/-0.5
orbitals that are further away from nucleus
have higher potential energy.
Pauli Principle
: No two electrons in an atom can have all four quantum
numbers the same. What this means is that any orbital (defined by n, l
and ml
) can have a maximum of two electrons, one with ms
= +1/2 and
one with ms
= –1/2.
Aufbau Principle:
Electrons are placed in the lowest energy orbitals
available. For a given value of n, s lower than p lower than d, i.e. 3s < 3p
< 3d except in the special case of hydrogen where energy depends only
on n.
Hund’s Rule:
For degenerate (same energy) orbitals, electrons start by
going one into each.
why does 4s fill before 3d
We say that the 4s orbitals have a lower energy than the 3d, and so the 4s orbitals are filled first.
why does 4s fill before 3d
We say that the 4s orbitals have a lower energy than the 3d, and so the 4s orbitals are filled first.
orbitals
probabiltiy where an electrons is found
1s
sphere
2s
larger sphere
valence electron
, feels a positive charge less
than the full nuclear charge.
Effective Nuclear Charge,
Z*
where Z* = Z – S.
Z is the actual nuclear charge (the atomic number) and S is a shielding constant.
effective nuclear change
Z* increases substantially across a row and increases down a group.
