1.1 Atomic Structure Paper 1 and 2 Flashcards
Which is the letter used to represent the atomic number of an atom
Z
What does the atomic number tell us about an element
Number of protons in an atom
What letter represents mass number
A
How is the mass number calculated
Mass number = number of protons + number of neutrons
Define relative atomic mass
Average mass of all isotopes of an element compared to 1/12 the mass of an atom of carbon 12
What are isotopes of an element
Different forms of the same element containing the same number of protons but different numbers of neutrons
They have the same chemical properties
How many orbitals and electrons does an s shell contain
1 orbital
2 electrons
How many orbitals and electrons does a p shell contain
3 orbitals
6 electrons
How many orbitals and electrons does a d shell contain
5 orbitals
10 electrons
Does 3d or 4s have a higher energy
3d
What is an orbital
A region around the nucleus that can hold up to 2 electrons
What would be the relationship between 2 electrons in the same orbital in terms of their spin
Have opposite spin as repel eachother as both negative
Why does chromium not fit the trend for electronic configuration
It only has 1 electron in its 4s orbital before filling 3d
1s2… 3p6 4s1 3d5
Why does copper not fit the trend for electronic configuration
It only has 1 electron in its 4s orbital before filling 3d
1s2…. 3p6 4s1 3d10
Which sub shell do ions lose electrons from first
4s
What does electron impact do
An electron gun (hot wire filament with current through it emitting electrons) knocks off one electron from each particle to form 1+ molecular ions
What does electrospray do
Sample dissolved in volatile solvent and injected through a fine hypodermic needle attached to positive terminal of a high voltage power supply into mass spec as a fine mist
When would you use the different types of ionisation in mass spec
Electron impact - organic or inorganic molecules with a low formula mass
Electrospray - substances with higher molecular mass including biological molecules eg proteins
Describe how TOF acceleration works
Positive ions attracted towards a negatively charged plate(electric field), same KE
Describe how TOF ion drift works
Ions pass through hole in plate, form a beam with constant kinetic energy, travel along tube to detector.
Describe how TOF detection works
Positive ions hit negative plate, current produced, m/z value and time of flight recorded. Largest current from most abundant ions
Define first ionisation energy
The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions
