Coordination Compounds and Nuclear Reactions

Question 1

What is a coordination compound?

Answer 1

• A combination of two or more atoms, ions, or molecules where a bond is formed by sharing a pair of electrons originally associated with only one of the compounds
  
  • It’s a coordinate covalent bond
  • The electron pair that is donated doesn’t have to be a lone pair. It could also be a pi bond from a double bond
  • The charge is the sum of the charges
  • Ex: a metal with ligands around it

Question 2

What gives coordination compounds different colors?

Answer 2

• Crystal field theory predicts the color of a coordination complex
  
  • D orbital splitting in transition metals.
    
    • When ligands attach to a transition metal to form a coordination complex, electrons in the d orbital split into high energy and low energy orbitals.
    • The amount that they split (Δ_^o) depends on what’s the metal in the center, and the ligand
    • A photon equal to the energy difference ∆o can be absorbed. Larger energy differences changes the color.
      
      • If one ligand has a bigger splitting than another ligand, it will absorb the higher energy photon with the smaller wavelength, and transmit longer wavelength

Question 3

What are common structures for coordination compounds?

Answer 3

• Most common is octahedral
• Very few tetrahedral complexes

Question 4

What are isomers and their different types?

Answer 4

• Structures are isomers if they have the same chemical formula
• If they don’t have the same order of atom attachment, they’re constitutional isomers
• If they can be made identical by rotation around a single bond, they’re conformational isomers
• If they are mirror images, they’re enantiomers
• If they aren’t mirror images, they’re diastereoisomers

Question 5

What is binding energy and mass defect?

Answer 5

• Binding energy keeps the nucleus bound together - HUGE energy
• Mass and energy can be converted into one another, and there is a missing mass in the nucleus that is the mass of the binding energy
  
  • E=mc²

Question 6

When will a nuclei decay?

Answer 6

• If it has more than 83 protons
• Usually breaks into a slightly more stable form, and a small alpha or beta particle

Question 7

What are alpha particles?

Answer 7

• an alpha particle is a helium nucleus
  
  • mass 4, atomic number 2
  • 2+ charge is understood, not written
  • can be stopped by paper
• In a emission, the mass number decreases by 4 and the atomic number decreases by 2

Question 8

What is beta decay?

Answer 8

• Emit beta particles
  
  • can be electron or positron (specifically positron emission)
• When there is a gain or loss of 1 atomic number and no change in mass number, that’s beta decay

Question 9

What is gamma decay?

Answer 9

• Emits gamma particles
  
  • Gamma particles are really high energy photons
• Product has lower energy

Question 10

Kinetics for decay?

Answer 10

• Follow first order kinetics - rate is dependent on concentration of reactant
  
  • Exponential decay
• After each successive half-life, one half of the original amount remains

Question 11

How do you write a nuclear reaction equation?

Answer 11

• Mass number and atomic number has to add up to same on both sides of arrow