Inorganic Chemistry: 1: Electromagnetic Radiation and Atomic Spectra

Question 1

What are the three methods that can be used to gain information about the species within a sample?

Answer 1

Colorimetry

Atomic emssion spectra

Atomic absorbtion spectra

Question 2

What equation is used to calculate the energy carried by a single photon of light?

Answer 2

E=hf

Question 3

What is the equation used to calculate the energy carried by a mole of photons?

Answer 3

E-Lhf

Question 4

How does atomic absorbtion spectra work?

Answer 4

Electromagnetic radiation is directed at an atomised sample and the wavelengths of radiation will be seen by the spectrum produced.

Question 5

How does atomic emission spectra work?

Answer 5

High temperatures are used to exite electrons from their ground state to higher, quantised, energy levels. As the electrons fall back to their ground state a photon of light will, with a specific wavelength will be emitted.

Question 6

What is ionisation?

Answer 6

This is where an electron is exited from it sub shell “n” where “n” is a positive integer to n=infinity.

Question 7

Calculate the ionisation energy in kJmol^-1 of a hydrogen atom from the spectral information that the lyman series converges at 91.2nm

Answer 7

E=1313kJmol^-1

Question 8

What is the first quantum number?

Answer 8

The principle quantum number, n.

It can have a value of n=1, 2, 3, 4… and the number determines the main energy level and size of the shell.

Question 9

What is the second quantum number?

Answer 9

The angular momentum quantum number, l.

It can have values from 0 to n-1. This determine the shape of the subshell which are labelled s, p, d or f.

Question 10

In relation to the second quantum number, l, what are the possible values of “l” if n=4 and what would the sub shells be labelled as?

Answer 10

l=0. s shell
l=1. p shell
l=2. d shell
l=3. f shell

Question 11

What is the third quantum number?

Answer 11

The magnetic quantum number, ml.

Ml is depenent on ml and can have any value between -l and +l.

Question 12

In relation to the third quantum number, ml, what would the values for ml be if l=2?

Answer 12

ml= -2, -1, 0, 1, 2

Question 13

What is the fourth quantum number?

Answer 13

The magnetic spin quantum number, ms.

This can have values of either +1/2 or -1/2. This determines the spin of the electron.

Question 14

What is the ground state of an atom?

Answer 14

This is the lowest possible electron configuration the electrons within an atom can adopt.

Question 15

What is the Heisenburg uncertainty principle?

Answer 15

It is impossible to state precisely the position and the momentum of an electron at the same instant, if treated like a particle.

Question 16

What is the definition of an atomic orbital?

Answer 16

The space within an atom where the probability of finding an electron is >90%.

Question 17

What are the three rules used to determine the ground state of an atom?

Answer 17

Auf Bau principle, Pauli exclusion principle and Hund’s rule.

Question 18

What is the Auf Bau principle?

Answer 18

Orbitals with the lowest energy are filled first.

Question 19

What is the Pauli exclusion principle?

Answer 19

No two electrons within the same atom can have the same four quantum numbers.

As a consequence, each orbital can only hold a maximum of two electrons which both must have opposite spins.

Question 20

What is Hund’s rule?

Answer 20

When there are degenerate orbitals in a sub shell, electrons fill each orbital singly with parallel spins before forming pairs