Intro to Orbitals and Bonding

• What is the size range of a nucleus?

  10$^{-14}$ to 10$^{-15}$ m
• What is the mass of electrons compared to protons?

  Negligible mass
• How far do electrons circulate around the nucleus?

  About 10$^{-10}$ m
• What is the charge of a proton?

  +1
• What is the mass of a neutron in amu?

  1.00866
• What is the charge of an electron?

  -1
• Where is most of the mass of an atom located?

  In the nucleus
• What occupies most of the volume of an atom?

  Electrons

  
• What defines the atomic number of an element?

  • The number of protons in the nucleus
  • Defines the element
• How do electrons occupy shells around the nucleus?

  In concentric shells surrounding the nucleus
• What are atomic orbitals?

  Subshells within electron shells

  
• What does an orbital describe?

  Probability of locating an electron

  
• What is the maximum number of electrons in an atomic orbital?

  Two electrons
• What must the spins of two electrons in an orbital be?

  Opposite spin
• What types of atomic orbitals exist?

  • s orbitals
  • p orbitals
  • d orbitals
  • f orbitals

  
• What is a node in a p orbital?

  Region of zero electron density
• What is the ground state of an atom?

  Lowest-energy electronic configuration

  
• What are core electrons?

  Electrons in a full shell
• What are valence electrons?

  Electrons in incomplete shells
• What are the rules for filling atomic orbitals?

  1. Aufbau principle: Fill lowest-energy orbitals first
  2. Pauli exclusion principle: Two electrons per orbital, opposite spins
  3. Hund's rule: Half-fill orbitals of equivalent energy first

  
• What is the electron configuration for Lithium (Li)?

  1s$^2$ 2s$^1$
• What is the electron configuration for Neon (Ne)?

  1s$^2$ 2s$^2$ 2p$^6$
• What is the Octet Rule?

  Atoms are stable with 8 outer electrons
• What happens to elements in group 1A?

  They lose an electron to form cations
• What is ionic bonding?

  • Transfer of electrons between a metal and a non-metal
  • Forms positive and negative ions
  • Results in a stable ionic compound
• What is the electron configuration for Sodium (Na)?

  1s$^2$ 2s$^2$ 2p$^6$ 3s$^1$
• What is the electron configuration for Chlorine (Cl)?

  1s$^2$ 2s$^2$ 2p$^6$ 3s$^2$ 3p$^5$
• What are the chemical formulae for common ionic compounds?

  • Sodium fluoride: NaF
  • Calcium bromide: CaBr$_2$
  • Aluminium oxide: Al$_2$O$_3$
  • Copper (I) oxide: Cu$_2$O
  • Copper (II) oxide: CuO
  • Iron (III) oxide: Fe$_2$O$_3$
  • Manganese (IV) oxide: MnO$_2$
• What is a covalent bond?

  Sharing a pair of electrons between atoms
• Why do some elements exist as diatomic molecules?

  They share electrons to achieve filled shells
• What is a single covalent bond composed of?

  Two electrons

  
• What is the significance of Lewis structures?

  Show all valence electrons in a molecule
• What does valence bond theory state?

  Covalent bonds form from overlapping orbitals
• What type of bond is formed from overlapping 1s orbitals?

  Sigma (σ) bond

  
• What is the bond strength of the H-H bond?

  436 kJ/mol

  
• What is the bond length of H2?

  0.74 Å
• What is molecular orbital theory?

  • Electrons occupy molecular orbitals
  • Formed from atomic orbital wave functions
  • Bonding and antibonding orbitals created

  
• How are molecular orbitals filled with electrons?

  Starting at the lowest energy available

  
• What is the difference between bonding and antibonding molecular orbitals?

  Bonding orbitals are lower in energy

  
• How many electrons can a molecular orbital accommodate?

  Two electrons