Physical- Atomic Structure Flashcards
What letter is the symbol for atomic number in the periodic table?
Z
What letter is the symbol for mass number in the periodic table?
A
What is the relative atomic mass?
The average mass of all isotopes of an element compared to 1/12 the mass of an atom of Carbon 12
What is a isotope of an element?
Different forms of the same element, both containing the same number of protons but a different number of neutrons
How do you work out the average mass of an element?
(abundance of A x mass of A) + (abundance of B x mass of B) divided by the total abundance
What is Avogadro’s constant?
6.02 x 10-23
How do you work out the mass of one atom?
Mass of one mole divided by Avogadro’s constant (convert to kg)
What is a mass spectrometer?
An instrument used to accurately determine the relative atomic mass
What are the six stages of a mass spectrometer?
1- vaporisation
2- ionisation
3- electric field
4- ion drift
5- detector
6- mass spectrum
What are the two types of ionisation for a mass spectrometer?
Electron impact- electron gun fired at atom, knocks of outer shell electron to form a +1 ION
Electrospray ionisation- sample is dissolved in a volatile solvent and injected through a needle which is attached to a high voltage power supply
What are the two equations used in TOF calculations?
KE=1/2 x m x v2
v=d divided by t
What is the first ionisation energy?
The minimum amount of energy needed for one mole of the outermost electrons to be removed from one mole of atoms in a gaseous state
What is the equation for the first ionisation energy in an element?
Mg(g) —> Mg+(g) + e-
How are ions detected in a mass spectrometer?
When they hit the detector they generate a current
How is the abundance of isotopes measured in a mass spectrometer?
The current produced is proportional to the abundance
Why do isotopes have similar chemical properties?
Because they have the same number of electrons in their outer shell
How do successive ionisation energies give evidence for sub-shells and shells?
A bigger jump in the amount of energy required between successive ionisation energies indicates a change in sub-shells or shells since the electrons are closer to the nucleus
What is the second ionisation energy?
The energy required to remove one mole of electrons from one mole of gaseous positive ions to form one mole of 2+ gaseous ions and one mole of electrons
