Quantum theory

Question 1

quantum mechanics definition

Answer 1

which is the theory neededto describe the behaviour of individual atoms, molecules and the electrons theycontain.

Question 2

Atomic orbitals

Answer 2

follows the laws of quantum mechanics

Question 3

quantized

Answer 3

energy cannot take any level. it is restricted to a certain set of values, usually called energy levels,

Question 4

location and quantum mechanics

Answer 4

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,

Question 5

wave fucntion

Answer 5

variable quantity that mathematically describes the wave characteristics of a particle

Question 6

wave function symbol

Answer 6

psi.

Question 7

atomic spectra

Answer 7

the spectrum of frequencies of electromagnetic radiation emitted or absorbed during transitions of electrons between energy levels within an atom.

Question 8

The principal quantum number,

Answer 8

n, describes the energy of an electron and the most probable distance of the electron from the nucleus.
n =1,2,3,4

Question 9

The azimuthal number L

Answer 9

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

Question 10

§ Magnetic quantum number

Answer 10

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…………………

Question 11

Spin quantum number

Answer 11

0.5/-0.5

Question 12

Spin quantum number

Answer 12

0.5/-0.5

Question 13

orbitals that are further away from nucleus

Answer 13

have higher potential energy.

Question 14

Pauli Principle

Answer 14

: 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.

Question 15

Aufbau Principle:

Answer 15

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.

Question 16

Hund’s Rule:

Answer 16

For degenerate (same energy) orbitals, electrons start by
going one into each.

Question 17

why does 4s fill before 3d

Answer 17

We say that the 4s orbitals have a lower energy than the 3d, and so the 4s orbitals are filled first.

Question 17

why does 4s fill before 3d

Answer 17

We say that the 4s orbitals have a lower energy than the 3d, and so the 4s orbitals are filled first.

Question 18

orbitals

Answer 18

probabiltiy where an electrons is found

Question 19

1s

Answer 19

sphere

Question 20

2s

Answer 20

larger sphere

Question 21

valence electron

Answer 21

, feels a positive charge less
than the full nuclear charge.

Question 22

Effective Nuclear Charge,

Answer 22

Z*
where Z* = Z – S.
Z is the actual nuclear charge (the atomic number) and S is a shielding constant.

Question 23

effective nuclear change

Answer 23

Z* increases substantially across a row and increases down a group.

Question 24

ionisation energy

Answer 24

is a endothermic reaction. energy is needed to break bonds.

Question 25

why does effective nuclear charge increase along row

Answer 25

there are more protons

Question 26

why does effective nucleur charge decrease down group

Answer 26

greater shielding and distance

Question 27

why does effective nuclear charge decrease

Answer 27

‘Kinks’ in the graph at B/Al reflect change in orbital type: p instead of s

Question 28

hunds rule effective nuclear charge

Answer 28

‘Kinks’ in the graph at O/S reflect electrons now paired in an orbital.
Hund’s Rule.

Question 29

electronegativity

Answer 29

‘the ability of an atom to attract electron density
towards itself in a molecule’

Question 30

ionisation
energies

Answer 30

energyit takes to become 1+ cation ions gaseous

Question 31

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