Atomic Structure

Question 1

Series when n1 = 1?

Answer 1

Lyman UV
n1 = 1
n2 = 2, 3 ,4…

Question 2

Series when n1 = 2?

Answer 2

Balmer Visible
n1 = 2
n2 = 3, 4 ,5…

Question 3

Series when n1 = 3?

Answer 3

Paschen Infrared
n1 = 3
n2 = 4, 5, 6…

Question 4

Series when n1 = 4?

Answer 4

Brackett Infrared
n1 = 4
n2 = 5, 6 ,7….

Question 5

Series when n1 = 5?

Answer 5

Pfund Infrared
n1 = 5
n2 = 6, 7, 8…

Question 6

Ionisation energy of hydrogen?

Answer 6

Minimum energy required to completely remove the electron from an atom

Question 7

What is the wave function?

Answer 7

Mathematical function that varies with position

Question 8

What is the radial wave function R(r)?

Answer 8

Contains information about what happens to the wave function as distance from the nucleus increases

Question 9

What is the angular wave function?

Answer 9

Contains information about the shape of the orbital

Question 10

What is the Bohr radius?

Answer 10

The distance from the nucleus to the electron in the Bohr model off the hydrogen atom and is the most probably distance for finding the 1s electron from the nucleus in the quantum mechanical approach

Question 11

What is R(r)^2?

Answer 11

Probability of finding an electron with a volume at a distance r from the nucleus - equivalent to the electron density at that point

Question 12

What is the radial distribution function?

Answer 12

Most probable distance of finding an electron from the nucleus - the maximum in a radial distribution function represent the most probable distance fro the electron from the nucleus

Question 13

Five d orbitals?

Answer 13

dxy 
dyz 
dxz 
dx^2-y^2 
dz^2

Question 14

Why does dz^2 have odd shape?

Answer 14

Schrödinger equation produces six solutions for l=2 but only five allowed values of ml, instead of throwing away a valid answer combine the two solution corresponding to dz^2-x^2 and dz^2-y^2 to give the dz^2 orbital

Question 15

Aufbau principle?

Answer 15

Involves building up the electronic structure of an atom by filling the lowest energy orbitals first

Question 16

Pauli exclusion principle?

Answer 16

No two electrons in an atom can have the same four quantum numbers - a maximum of two electrons can reside in any orbital

Question 17

Hunds rule?

Answer 17

Ground state is the arrangement with the maximum number of parallel electrons

Question 18

Scandium electronic configuration?

Answer 18

[Ar]3d1 4s2

Question 19

Chromium electronic confirmation?

Answer 19

[Ar]3d5 4s1

Question 20

Shielding?

Answer 20

In an atom with more than one electron there are electron repulsions as well as attractive interactions between nucleus and electron,t he repulsions shield electrons from full nuclear charge - charge felt by 2s electrons is less than actual charge due to shielding from 1s electrons.
2p electrons more effectively shielded than 2s electrons.

Question 21

Penetration?

Answer 21

The presence of the radial node means there is an area of electron density relatively close to the nucleus for the 2s electrons - this electron density is largely absent for a 2p electron. 2s electrons said to penetrate 1s electrons, 2s electrons feels a higher efficient nuclear charge than a 2p electron. The 2s orbitals is stabilised more than the 2p orbital. S electrons more penetrating than p electrons and p electrons more penetrating than d electrons due to shapes of radial distribution functions.

Question 22

Effective nuclear charge across a period?

Answer 22

Zeff felt by outermost electrons increases across a period, since electrons in the same shell do not shield etc other very effectively from the nuclear charge.

Question 23

Atomic radius of element?

Answer 23

Half the distance between the nuclei of neighbouring atom in the pure element.
If the element is a metal this becomes the metallic radius.
If the element is a non metal this becomes the covalent radius

Question 24

Atomic radius size trends?

Answer 24

Across a period decrease due to increasing Zeff pulling electrons closer to the nucleus and decreasing the atomic radius

Question 25

For group 18 elements van der waals radius?

Answer 25

For an atom is half the distance between non bonded nuclei of neighbouring atoms in the structure of the solid, considerably larger than covalent radii.

Question 26

Zeff down a group?

Answer 26

Decrease slightly down a group for the first few atoms before reaching a plateau

Question 27

Atomic radii down group?

Answer 27

Increases down group, each electron lies in a larger orbital

Question 28

Cationic and anionic radii?

Answer 28

Decrease across a period increase down a group

Question 29

Ionisation energy?

Answer 29

Energy change when an electron is removed form an atom of the element in the gas phase - all ionisation reactions are endothermic they require an input of energy to occur so all have positive values.
Gneral increase in first ionisation energy from left to right across each period consistent with the increases in Zeff, electrons held more tightly so takes more energy to remove them
Decreases down a group electron being removed form a atomic orbital further form he nucleus

Question 30

Electron gain energy?

Answer 30

The energy change that occurs when an electron is attached to an atom in the gas phase - first electron gain enthalpies becomes increasingly negative from left to right across a period

Question 31

Radial node?

Answer 31

Radial nodes are spherical

Question 32

Angular node?

Answer 32

Angular nodes are typically flat planes

Question 33

Chromium electronic configuration?

Answer 33

[Ar]3d5 4s1

all other transition metals have 4s2 electrons

Question 34

Copper electronic configuration?

Answer 34

[Ar]3d10 4s1

all other transition metals have 4s2 electrons