Atomic Structure Flashcards
What is the Significance of the M+1 mass spectra peak?
The last peak of a Mass spectra
Used to estimate number of carbon atoms in compound
Explain Electron Impact ionisation
Sample is vaporised
High energy electrons fired at sample using an electron gun
Knocks off an electron from most atoms forming +1 ions
X(g) +e- ——-> x+ + 2e-
Explain Electrospray ionisation
Sample is dissolved in volatile solvent
This solution is injected through a fine hypodermic needle
The needle tip is attached to the positive terminal of a high voltage supply
Particles are ionisation by gaining a proton
X(g) + H+ —-> XH+ (g)
Explain Acceleration in Mass spec
The positively charged ions are accelerated through an electric field so each particle has an equal kinetic energy
Heavier Particles have less velocity as a result ,this allows a difference in interval time relative to the particles mass
Explain Ion Drift in Mass Spec
The positive ions travel through a hole that is negatively charged to guide it through the flight tube
Explain Detection in Mass Spec (3)
Positively Charged Ions hit the detector plate which is negatively charged
They gain electrons which completes a circuit within the machine causing a spike in current,
The higher the current the larger abundance of particles
What is special bout Copper be Chromium’s Electronic configuration
Half filled 4s orbitals
Define Eletronegativity
The ability of an atom or molecule to attract its eletron density towards itself within a covalent bond
Define the term relative atomic mass
Mean mass of an atom
relative to 1/12th the mass of a carbon-12 atom
While doing Mass spec questions.
What 3 things do you have to remember
1) Convert grams into kilograms
2)Mr is the mass of a mole of molecules
3) All molecules are positive ions
Identify the oxidation states for all elements is Sodium Hydride
+1 = Na
-1 = H
Hydrogen is -1 oxidation state when it is a metal hydride
Give the electron config for Ca2+
1s2 2s2 2p6 3s2 3p6
4s2 is emptied first
Why is the second ionisation energy of calcium lower then second ionisation energy of potassium
Potassium’s 2nd ionisation energy removes an electron that is closer to the nucleus
There are stronger forces of attraction for electrons that are closer to the nucleus
Calcium removes an electrons from another sub energy level, hense it has more shielding
Both means less energy is needed to remove a second successive elytron from potassium the calcium.
Which s Block metal has the highest first ionisation energy
Beryllium
These 3 isotopes are run under TOF mass spec after they were ionised by eletron impact
136Ba. 137Ba. 138Ba
Which ion has the longest retention time
138Ba + (dont forget +)
