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s and p Bonds MO Theory

s and p Bonds MO Theory. MO Theory: s orbitals . s orbitals form s and s * molecular orbitals Add and subtract orbitals to get the bonding and anti-bonding orbitals Start with 2 atomic s orbitals end with 2 molecular orbitals.

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s and p Bonds MO Theory

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  1. s and p BondsMO Theory

  2. MO Theory: s orbitals • s orbitals form s and s* molecular orbitals • Add and subtract orbitals to get the bonding and anti-bonding orbitals • Start with 2 atomic s orbitals end with 2 molecular orbitals. • Fill in electrons from low to high energy, just like in atomic orbital diagrams 1s-1s Anti-bonding MO, σ*1s E isolated H atoms 1s+1s Bonding MO, σ1s

  3. MO Theory: p orbitals • p orbitals form sand s* molecular orbitals or p and p* orbitals depending on type of overlap • Add and subtract orbitals to get the bonding and anti-bonding orbitals • Start with 6 atomic orbitals end with 6 molecular orbitals • Fill in electrons from low to high energy, just like in atomic orbital diagrams End to end overlap Side to side overlap

  4. Why do we need MO theory if we have hybridization?(plus MO diagram building practice snuck in) • Part A) Draw the Lewis structure of oxygen. • Decide based on the lewis structure what the bond order should be and using valance bond theory whether it is paramagnetic or diamagnetic.

  5. Atomic Atomic MO Diagram of Oxygen • Part B) Draw the MO diagram of oxygen • Decide based on the MO structure, what the bond order should be and whether it is paramagnetic or diamagnetic. • Tip: if possible, try doing this from scratch without looking at your notes from the video. See what mistakes you make and what you forget to do.

  6. Practice • The ground-state electron configuration of the ion C2n- is s2s2s2s*2p2p4s2p2. • What is the charge on the anion? • Draw the MO diagram. • Is it paramagnetic or diamagnetic? • What is the bond order? • Hint: ½(bonding electron-antibonding electrons) • Would adding an electron add or subtract from the bond order? • Would subtracting an electron make the bond longer or shorter?

  7. Heteronuclear Practice • For CN the energy of the molecular orbitals follows the order of carbon (a.k.a. p2p<s2p) • Draw the MO diagram. • Give the valence shell electron configurations of CN and CN-. • Are they paramagnetic or diamagnetic? • Tell the bond order of each. • Which has the stronger bond?

  8. Practice • Consider the hypothetical species HeH. What charge, if any, should be present on this combination of atoms to produce the most stable molecule or ion possible? • Draw the MO diagram for the neutral species first. • Decide what ion gives largest bond order • What is the bond order on the neutral species and what bond order, if changed, is on the ion you chose? • If the charge on the neutral species were increased or decreased by one what would be the affect on the bonding of the atom. • If the charge on the species you chose were increased or decreased by one what would be the affect on the bonding of the atom.

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