Atomic Structure Flashcards
What is the relative mass and charge of particles in an atom?
Proton = (mass) 1, (charge) +1
Neutron = (mass) 1, (charge) 0
Electron = (mass) 1/1840, (charge) -1
What is the exact mass and charge of particles in an atom?
Proton = (mass) 1.673×10^-27, (charge) +1.602×10^-19
Neutron = (mass) 1.675×10^-27, (charge) 0
Electron = (mass) 0.911×10^-30, (charge) -1.602×10^-19
Define Isotope.
Atoms that have the same atomic number, different atomic mass so same number of protons, different number of neutrons.
Why do isotopes behave the same chemically?
They have the same number of electrons which determines the chemical behaviour of elements.
What is Mass Spectroscopy?
Analytical technique that identifies different isotopes and finds the relative atomic mass of the element.
Where can Mass Spectroscopy be used?
Used by forensic scientists (identify substances), and space probes (identify carbon compounds in rock samples).
What are the 5 stages of Time of Flight Mass Spectroscopy?
- Vaporisation
- Ionisation
- Acceleration
- Deflection/ Ion Drift
- Detection
What is Vaporisation in TOF?
Substance is vaporised (gas) and injected into vacuum (to prevent colliding with air).
Describe Electrospray Ionisation
Tiny droplets of the molecule become positively charged. Vacuum causes solvent to evaporate, leaving MH+ to be attracted to negative plate.
Give the equation for Electrospray Ionisation.
M (l) + H+ -> MH+ (g)
M= Molecule
H+ = proton from solvent
Why is Electrospray Ionisation used for?
Used to detect high Mr Molecules.
What is Electron Impact Ionisation?
Electron gun (high voltage) fires causing high-energy electrons to take/knock an electron from the sample, forming positive ions.
What is the equation for electron impact ionisation?
X (g) -> X+ (g) + e-
What is electron impact ionisation used for?
Used for elements and low Mr Compounds.
Describe Acceleration in TOF
Positively charged ions are attracted to the negatively charged plate and accelerated to the same kinetic energy.
Describe Ion Drift in TOF
Ions pass through a hole in the plate and form a beam to travel along the flight tube towards the detector.
What is Detection in TOF?
Positive ions pick up an electron from the detector, vausing current to flow. Size of current is proportional to relative abundance.
What are orbitals?
Clouds of negative charge which electrons are in.
How many orbitals are in each sub-level?
S = 1 (2e-)
P = 3 (6e-)
D = 5 (10e-)
F = 7 (14e-)
Identify the sub-level blocks on the Periodic Table.
S-Block = G1, G2, He
P-Block = G3, G4, G5, G6, G7, G0
D-Block = Transition Metals
F-Block = Radioactive Elements
What are element exceptions in electron configuration?
Cr = 1s2 2s2 2p6 3s2 3p6 4s1 3d5
Cu = 1s2 2s2 2p6 3s2 3p6 4s1 3d10
What is the electron configuration of the two exceptions as ions?
Cr3+ = 1s2 2s2 2p6 3s2 3p6 3d3
Cu2+ = 1s2 2s2 2p6 3s2 3p6 3s9
Define Ionisation Energy.
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
Give the general equation for Ionisation Energy.
X (g) -> X+ (g) + e-
What is the trend in ionisation energy down the group?
Decreases.
Increasing atomic radius means more shielding which means weaker forces of attraction between nucleus and outer shell electron.
How do successive ionisation energy diagrams give evidence for the atomic orbital theory?
Sudden increases in energy level indicate the big jump in energy needed to remove an outer electron from a sub-level closer to the nucleus.
