Atoms Flashcards
Where’s are the electrons?
On orbitals
Relative mass of proton?
1
Relative number of neutron
1
Relative number of electron
1/1800
Charge of proton
+1
Charge of neutron
0
Charge of electron
-1
On the periodic table which number is the total number of protons and neutrons in the shell?
Mass number the bigger one
What’s the smaller number on the periodic table?
Atomic mass number of protons in the nucleus.
Define isotope
Atoms with same number of protons but different number of neutrons
Why do isotopes have similar chemical structure?
Same electronic structure
Why might isotopes have slight differing physical properties?
Different masses
What can mass spectrometer be used for?
To determine all isotopes present in a sample of an element and therefore identify elements
Why does mass spectrometer need to happen underneath a vacuum?
Air particles would ionise and register on the detector
What are the four stages of mass spectrometer?
1) ionisation
2) acceleration
3) drift area
4) detection
What happens in ionisation?
Sample dissolved in polar solvent
High voltage applied to sample
Particles lose an electron (or more)
Form positive charges with different charges
What happens in acceleration?
Positive ions accelerated by electric field
To constant kinetic energy
What’s in the nucleus of an atom?
Proton and neutrons
What’s in drift area?
Positive ions with smaller m/z values will have same energy as those with larger m/z values and will move faster. Heavier particles take longer through the drift zone. Ions are distinguished by different flight times
What’s in detection?
Ions reach detector and generate a small current which is fed into computer for analysis. Current produced by electrons transferring from detector to positive ions. Size of current is proportional to the abundance of the species.
How to calculate RAM?
RAM= all(isotope mass* relative abundance)/ total relative abundance.
First ionisation define ?
The first ionisation energy is the enthalpy change when one mole of gaseous atoms forms mole of gaseous ion with a single positive charge
H(g)->H+(g) +e-
Ionisation two?
The second ionisation energy is the enthalpy change when one mole of gaseous ion forms one mole of gaseous ions with a double positive charge
H+(g) -> H2+(g) +e-
What are the shells
S
P
D
F
What are the factors that affect ionisation energy?
1) attraction of the nucleus
2) distance from the nucleus
3) shielding of the attraction of the nucleus
Why are successive energies always larger?
When the first electron is removed a positive charge is formed. Ions increases attraction on remaining electrons so energy required to remove the next election is larger.
