Atomic Structure Flashcards
(19 cards)
What are the relative masses and charges of subatomic particles
Proton: 1, +1
Neutron: 1, 0
Electron: 0.0005, -1
What is an isotope?
Atoms of the same element with different mass number but same atomic number
What is relative atomic mass
The average mass of an atomic of an element relative to 1/12 of an atomic of carbon-12
What is relative isotopic mass
The mass of a single isotope of an element relative to 1/12 of an atomic of carbon-12
What is mass spectrometry used for
Determine information about elements and compounds, determining relative isotopic masses of the isotopes of elements and their relative abundance
What are the stages of time of flight spectroscopy
- Electrospray ionisation
- Acceleration
- Ions drift
- Ion detection
- Data analysis
What is electrospray ionisation
High voltage applied to tip of capillary
Produces highly charged droplets
Solvent evaporates from droplets
Produces gaseous charged ions (mononuclear)
What is acceleration stage?
Electric field applied
All ions gain the same kinetic energy
Larger particles move with slower speed
Smaller particles move with faster speed
What is ion drift
Ions enter region with no electric field (flight tube)
Ions seperated based on different velocities
Smaller Ions move more rapidly and arrive at detector first
What is ion detection?
Detector records different flight times of the ions
The ions arrive and induced a small electric current by picking up electrons
What is data analysis
Flight times analysed and recorded by data analyser
Plot of relative abundance against mass to charge ratio (m/z)
What are ionisation energies
The energy required to remove one mole of electrons from an atom in its gaseous state
How are ionisation energies evidence for energy levels
Large gaps in successive ionisation energies
Corresponding to removal of electrons from energy levels closer to the nucleus
General increase is due to increased ratio of protons to electrons
Why do ionisation energies decrease down a group
Atomic radius decreases so greater nuclear attraction
Greater nuclear charge effect is cancelled out by extra shielding from more electron shells
Why do ionisation energies increase across a period
Atomic radius decreases due to increased nuclear charge but same levels of shielding
Explain the dip between group 2 and group 3
Atoms of group 3 have electrons present in p subshell
This is further from the nucleus and has additional shielding
Requires less energy to be ionised
Explain the dip between group 5 and 6
Group 6 atoms have electrons begining to pair up in the p subshell
Electrons repel due to their like charges
Requiring less energy to remove
Group 1 and 0 ionisation energies
Group 1 have the lowest first ionisation energy due to greatest atomic radius with lowest nuclear charge
Group 0 have the highest due to smallest atomic radius and highest nuclear charge
Second ionisation energy patterns
Group 1 have the highest second ionisation energies
Group 2 have the lowest
