Atomic Structure Flashcards
What is an orbital?
A cloud of negative charge
What are the different sub levels?
S, P, D, F (in order of lowest to highest energy level)
How many electrons can an orbital be occupied by?
Maximum of 2
How many electrons can an s sub level hold? How many orbitals?
- 2 electrons
- 1 orbital
How many electrons can a p sub level hold? How many orbitals?
- 6 electrons
- 3 orbitals
How many electrons can a d sub level hold? How many orbitals?
- 10 electrons
- 5 orbitals
What is an energy level?
A region of empty space occupied by electrons
What are energy levels made up of?
Different number of sub levels
What are sub levels made up of?
Different number of orbitals
What is the order of sub levels?
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s
What does a mass spectrometer do?
Gives information about:
- RAM of element
- Relative abundance of its isotopes
- Relative molecular mass of molecule if used to analyse a compound
What is the first step of TIME OF FLIGHT mass spectrometry (electrospray ionisation)?
- Sample dissolved in volatile solvent
- Injected through fine hypodermic needle at high pressure
- High voltage applied to end of needle —> each particle gains H+ ion (creates fine mist)
- Solvent evaporates —> XH+ ions attracted towards negative plate where they are accelerated
X(g) + H+ —> XH+(g)
What is the first step of TIME OF FLIGHT mass spectrometry (electron impact)?
- Sample is vaporised
- High energy electrons fired at sample using electron gun
- One electron knocked off each particle —> become +1 ions
CH4(g) —> CH4+ + e-
What is the second step of TIME OF FLIGHT mass spectrometry?
Acceleration:
- Positive ions accelerated by electric field
- Electric field gives same kinetic energy to all ions
- Lighter ions = greater acceleration (but same energy)
KE = ½mv²
What is the third step of TIME OF FLIGHT mass spectrometry?
Ion drift:
- Ions enter region with no electric field
- Drift through at the same speed as they left the electric field
- So lighter ions still drift at higher speeds
- Ions with different masses have different time of flights
t = d/v
t = d√m/2KE v measured in ms-¹
What is the fourth step of TIME OF FLIGHT mass spectrometry?
Detection:
- Positive ions hit negatively charged electric plate
- Hit detector plate —> positive ions discharged by gaining electrons from plate
- Generates movement of electrons
- Electric current is measured
- Size of current ∝ number of ions hitting plate (more ions = bigger current)
When is electospray ionisation used?
Used on substances with higher molecular mass
When is electron impact used?
Used in substances with lower formula mass
How do you calculate relative atomic mass?
Combined mass of all isotopes / Combined abundance of all isotopes
What is the 1st ionisation energy?
The energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
What is the equation for the 1st ionisation energy of oxygen?
O (g) —> O+ (g) + e‐
What are the 3 factors that affect ionisation energy?
- Nuclear charge
- Distance from nucleus
- Shielding
What is the 2nd ionisation energy?
The energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions
What is the equation for the 2nd ionisation of oxygen?
O+ (g) —> O²+ (g) + e-
Why is the 2nd ionisation energy greater than the 1st ionisation energy?
The electron is being removed from a positive ion, which requires more energy
