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1 volt = 1 joule / 1 coulomb

1 volt = 1 joule / 1 coulomb. 1 joule = 1 volt • 1 coulomb. How much energy would it take to move an electron across a potential difference of 1 volt?. 1 joule. x. =. 1 volt • 1 coulomb. 1 volt • 1.6 x 10 -19 coulomb. x = 1.6 x 10 -19 joules. = 1eV. AKA… an electron-volt.

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1 volt = 1 joule / 1 coulomb

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  1. 1 volt = 1 joule / 1 coulomb 1 joule = 1 volt • 1 coulomb How much energy would it take to move an electron across a potential difference of 1 volt? 1 joule x = 1 volt • 1 coulomb 1 volt • 1.6 x 10-19 coulomb x = 1.6 x 10-19 joules = 1eV AKA… an electron-volt

  2. Photoelectron Spectroscopy (PES): Provides direct evidence that electrons exist at certain energy levels. Discovered by Heinrich Hertz …Explained by Albert Einstein Based on the Photoelectric Effect • Atom is bombarded with photons • Photons are absorbed and electrons are emitted • The electrons are collected and their energy analyzed Einstein’s Photoelectric Effect Equation (binding energy) KE = hn – work. Ephoton = work required to eject the electron + KE (ionization energy)

  3. Photoelectron Spectroscopy (PES): Provides direct evidence that electrons exist at certain energy levels. Thus, for many atoms, electrons will be ejected from all possible energy levels. If this is sufficiently high, electrons can be ejected from any energy level in an atom…one e- per atom per photon

  4. Axes for a PhotoElectron Spectrum (MJ/mole e-)

  5. hydrogen PhotoElectron Spectrum for _________ 13.6 eV 1310 kJ/mole e- ← the single 1s electron ▲Work needed to remove the electron from the atom (gotten by knowing the energy of the photon and the KE of the photo-electron) i.e. “The ionization energy” (MJ/mole e-) The Binding Energy (1,310,000 J /mole e-) (1 mole e-/6.02 x 1023 ) ( 1 eV/1.6 x 10-19 J) = 13.6 eV

  6. PhotoElectron Spectrum for helium 24.6 eV ← the two 1s electrons ▲Work needed to remove one of the 1s electrons from the atom (MJ/mole e-) Why is the binding energy for a 1s electron in helium (24.6 eV) larger than the value for the removal of the electron in hydrogen (13.6 eV) ? MORE PROTONS IN THE NUCLEUS!

  7. PhotoElectron Spectrum for lithium ← the single 2s electron ← the two 1s electrons (MJ/mole e-) What is the first ionization energy for lithium in eV? 5.4 eV Why is this value smaller than the first ionization energy in He (24.6 eV)? Core Shielding

  8. PhotoElectron Spectrum for boron ← the two 1s electrons ↓ the single 2p electron ← the two 2s electrons (MJ/mole e-) Why is the binding energy for the 2s electrons (1.36 MJ/mole e-) a bit higher than that of the 2p electron (0.80 MJ/mole e-)? Due to the penetration of the 2s orbital relative to the 2p orbital.

  9. scandium PhotoElectron Spectrum for __________ ↓ the two 4s electrons ← the six 3p electrons ← the two 3s electrons ↑ the one 3d electrons (MJ/mole e-) What is the relative energy of the 4s electrons compared to the 3d electron once the atomic structure is configured? The 4s electrons represent a higher energy.

  10. PhotoElectron Spectrum for Scandium ↓ the two 4s electrons ← the six 3p electrons ← the two 3s electrons ↑ the one 3d electrons (MJ/mole e-) Why do you think that the 4s electrons has a higher energy than the 3d electron? The implication is the 3d electron shields the 4s electrons once the 3d begins to fill.

  11. PhotoElectron Spectrum for Scandium ↓ the two 4s electrons ← the six 3p electrons ← the two 3s electrons ↑ the one 3d electrons (MJ/mole e-) Which electrons, one of the 4s electrons or the 3d electron, would be easiest to remove? What would the first ionization energy be in kJ/mole e-? One of the 4s electrons, I.E.1= 630 kJ/mole

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