memorize

• Aufbau Principle: Electrons fill orbitals in order of increasing energy (ground state)
• Pauli Exclusion Principle: No 2 electrons in an atom can have the same 4 quantum numbers
• Hund's Rule: Degenerate (same energy) orbitals get an electron before pairing and the unpaired electrons have the same spin
• Cu: [Ar] 4s1 3d10
• Cr: [Ar] 4s1 3d5
• remove 4s before 3d and remove highest shell number first for transition metals
• Effective nuclear charge increases from left to right, getting smaller as they are attracted to the nuclues, atomic radius increases in opposite direction
• Bond length depends on atomic radius. the larger the atom the longer the bond
• Ionic radii cations are smaller than atoms and anions are larger than atoms.
• Isoelectronic series: The greater the atomic number z, the smaller the ionic radius
•  A high bond order indicates more attraction between electrons. A higher bond order also means that the atoms are held together more tightly.
• Exceptions for electron configuration: Cr, Au, Ag, Mo, Cu, Ru, Rh, Nb, Pt, Pd
• How many electrons does He hold?

  2
• How many electrons does H hold?

  1
• How many electrons does Boron and Aluminum hold?

  6
• How many electrons in Berylium? 4
• Expanded octet: 3 period and below
• ionization energy: left to right, up
• exceptions for IE:

  Be>B

  N>O

  Mg>Al

  P>S
• Which has the highest ionization energy? (hint: which of these when you go to remove a 2nd electron are you out of electrons)

  Na, Mg, Al, Si

  Na
• Electron Affinity: Element with larger negative electron affinity has higher electron affinity
• exceptions for electron affinity:

  group 2 metals with 1 filled subshell (be, Mg, Ca, Sr, Ba)

  noble gases