Atomic Structure Flashcards
Electron shell
Energy level within an atom that may be occupied by a fixed number of electrons
Subshell
Subdivision of an electron shell, containing a fixed number of orbitals at same energy level
Orbital
A region of space in which up to 2 electrons may be located
S subshell
2 electrons, one orbital
P subshell
6 electrons, 3 orbitals
D subshell
10 electrons, 5 orbitals
F subshell
14 electrons, 7 orbitals
The aufbau principle
It states that subshells are filled in order from lowest to hughest energy, and a lower-energy subshell will be completely filled before electrons move to a higher-energy subshell
Pauli exclusion principle
It states that only a maximum of two electrins mat be gound in an atomic orbital, and that if an orbital is filled the electrons will have opposite spin
Hunds rule
It states that electrons in a partially filled subshell will arrange themselces so as to form the maximum number of half filled orbitals (bc repulsion)
Order of subshell filling
1s,2s,2p,3s,3p,4s,3p etc
Radius size across the period (l to r)
Decreases bc more nuclear pull
Radius size down the group ( top to bottom)
Increases bc more energy levels
Core charge across the period (l to r)
Increases bc mire valence electrons tf less inner electrons
Core charge down the group ( top to bottom )
Remains constant
Electronegativity across the period (l to r)
Increases bc:
- number of occupied energy levels stays constant and atomuc radius decreases (bc increasing core charge)
- nuclear charge increases but number of inner shell electrons stay the same (shielding constant) so core charge increases
- tf valence mire strongly attracted ^ electroneg
Electronegativity down the group
Decreases bc:
- number of occupied energy levels increases, tf atomic radius increases
- nuclear charge increases, hw electron shielding (no of inner shell electrons) also increases so core chage remains same
- tf, further down, outermost electron is farther from nucl AND the more electrons an atom has bw outermost and nucl. Tf less attraction to nucl
Checklist for same period comparison (eg K and Br)
- shell no and atomic radius
- core charge and shielding
- radius and higher core charge and valence electrons = nuclear pull
THREE SENTENCES
Checklist for same group (eg Ca and Be)
- no of energy levels and atomic radius
- same core charge diff nuclear charge bc same inner shells BUT diff electron shielding
- larger atomic radius and equivalent core charge = valence of larger being more weakly attracted OR smaller has stronger pull
THREE SENTENCES
Ionisation energy trend down a group
Decreases
Ionisation energy across a period
Increasing bc bigger core charge
shape affects
melting point, boiling point, hardness and solubility
NO LONE PAIRS:
- 2 bonding pairs
- 3 bonding pairs
- 4 bonding pairs
linear, trigonal planar, tetrahedral
0,1,2 LONE PAIRS
tetrahedral, trigonal pyramidal, v-shaped/bent
