hund's rule

Examples of hund's rule in the following topics:

• Hund's Rule

  • For example, for boron through neon, the electron filling order of the 2p orbitals follows Hund's Rule.
  • According to Hund's Rule, all orbitals will be singly occupied before any is doubly occupied.
  • Hund's Rule also tells us that all of the unpaired electrons must have the same spin.
  • Orbital diagram for carbon, showing the correct application of Hund's Rule.
  • Apply Hund's rule and justify its use to determine electron configurations for atoms in the ground state

• Electron Configurations and Magnetic Properties of Ions

  • The Aufbau principle (from the German Aufbau, meaning "building up, construction;" also called the Aufbau rule or building-up principle) is used to determine the electron configuration of an atom, molecule, or ion.
  • If multiple orbitals of the same energy are available, Hund's rule states that unoccupied orbitals will be filled before occupied orbitals are reused (by electrons having different spins).
  • Order in which orbitals are arranged by increasing energy according to the Madelung rule.

• Bonding and Antibonding Molecular Orbitals

  • Three general rules apply:
  • Hund's rule states that when there are several MOs with equal energy, and the electrons occupy the MOs one at a time before two occupy the same MO.

• Quantum Numbers

  • The most prominent system of nomenclature spawned from the molecular orbital theory of Friedrich Hund and Robert S.

• Odd-Electron Molecules

  • Molecules with an odd number of electrons disobey the octet rule.
  • As the octet rule requires eight electrons around each atom, a molecule with an odd number of electrons must disobey the octet rule.
  • The two oxygen atoms in this molecule follow the octet rule.
  • Nitrogen dioxide is another stable molecule that disobeys the octet rule.
  • It does not obey the octet rule on the nitrogen atom.

• The Incomplete Octet

  • While most elements below atomic number 20 follow the octet rule, several exceptions exist, including compounds of boron and aluminum.
  • However, many atoms below atomic number 20 often form compounds that do not follow the octet rule.
  • In this compound, the boron atom only has six valence shell electrons, but the octet rule is satisfied by the fluorine atoms.
  • We might conclude from this one example that boron atoms obey a sextet rule.
  • Describe the ways that B, Al, Li, and H deviate from the octet rule

• A Useful Mnemonic Rule

• Naming Acids and Bases

  • Acid names are based on the anion they form when dissolved in water; base names follow the rules for ionic, organic, or molecular compounds.
  • There is a simple set of rules for these acids.
  • Therefore, strong bases are named following the rules for naming ionic compounds.
  • Therefore, they are named following the rules for molecular or organic compounds.

• Ionic Bonds

  • The octet rule states that an atom is most stable when there are eight electrons in its valence shell.
  • Atoms with less than eight electrons tend to satisfy the duet rule, having two electrons in their valence shell.
  • By satisfying the duet rule or the octet rule, ions are more stable.
  • Both ions form because the ion is more stable than the atom due to the octet rule.
  • This is because Mg has two valence electrons and it would like to get rid of those two ions to obey the octet rule.

• Designating the Configuration of Chiral Centers

  • The assignment of these prefixes depends on the application of two rules: The Sequence Rule and The Viewing Rule.
  • The sequence rule is the same as that used for assigning E-Z prefixes to double bond stereoisomers.
  • Another way of remembering the viewing rule, is to think of the asymmetric carbon as a steering wheel.
  • Rule # 3 of the sequence rules allows us to order these substituents.
  • Rule # 3 is again used to evaluate the two cases.