Bonding L11

Question 1

Continuous spectrum

Answer 1

Every wavelength of light is represented in the continuous spectrum

Question 2

Atomic emission spectrum

Answer 2

• Different energies=different colors

- Every element produces different emissions/colors

Question 3

Why do we have different colors of light?

Answer 3

• As wavelength/frequency changes, color changes
• But light behaves like a wave and it behaves like a particle
• As wavelength/frequency changes, the energy per photon changes

Question 4

Hybrid orbital theory

Answer 4

• Atomic orbitals on the same atom combine in order to form hybrids
• Atomic orbitals on different atoms overlap in order to form covalent bonds
• Each atom in the compound retains its associated orbitals and electrons
• This theory correlates with observed bond angles in molecules

Question 5

Molecular Orbital Theory

Answer 5

• Views molecules as a whole instead of a collection of individual atoms
• MOs are similar to atomic orbitals
• They both have specific energy levels
• Atomic orbitals combine to form MOs
• When two atomic orbitals combine, two MOs are formed
• Orbitals are always conserved

Question 6

Bonding orbital

Answer 6

• A MO that is lower in energy than any atomic orbitals from which it was derived
• Electrons that occupy these orbitals cause stability

Question 7

Anti-bonding orbital

Answer 7

• A MO that is higher in energy that any atomic orbitals from which it was derived
• Electrons that occupy these orbital cause instability

Question 8

Non-bonding orbital

Answer 8

• A MO that is at the same energy level as the one atomic orbital it was derived from
• Electrons that occupy these orbitals do not cause stability or instability
• Orbitals that contain lone pairs

Question 9

Spectroscopy

Answer 9

• A method of analysis which is based upon the absorbance of electromagnetic radiation by matter
• Used to acquire data pertaining to the structure of a molecule or the concentration of a species

Question 10

UV/V spectroscopy

Answer 10

• Examines transitions in electronic energy levels
• used to probe the electronic structure of certain compounds
• used to determine concentrations of solutions that contain certain compounds

Question 11

Infrared IR spectroscopy

Answer 11

• Examines transitions in molecular vibrations

- Is used to detect the presence of different types of bonds and to identify molecules

Question 12

UV/V graphs

Answer 12

• An absorption spectrometer is used to measure the absorbance of a sample at wavelengths between 200 and 800 nm
• The peaks represent wavelengths that correspond to the energy associated with possible electronic transitions within the molecule

Question 13

What transitions can take place in UV/V between 200nm and 800nm

Answer 13

• pi (bonding) to pi anti-bonding
• pi non-bonding to pi anti-bonding
• pi non-bondign to sigma anti-bonding

Question 14

beers law

Answer 14

A=abc

• A=absorbance
• a=molar absorptivity (M-1cm-1)
• b=path length of sample(cm)
• c=concentration (M)

Question 15

IR spectroscopy

Answer 15

• all covalent bonds in molecules are vibrating
• bond length is the average distance between nuclei
• Covalent bonds have a vibrational frequency that is in the IR region of the electromagnetic spectrum
• IR radiation of exactly the same frequency will be absorbed by the molecule
• vibration frequencies depend on the mass of the atoms and the strength of the bonds
• frequency is related to wavelength

Question 16

IR spectroscopy defining

Answer 16

• can be used to identify bond types, functional groups, and compounds
• every compound has a characteristic IR spectrum that it can be identified through

Question 17

IR peak

Answer 17

opposite because it shows low transmittance=most absorbed