Mass Spec and PES Lecture

Mass Calculation

Isotopes of Bromine: 78.92 amu (50.69%), 80.92 amu (49.31%)

78.92 (0.5092)+ 80.92 (0.4931)= 79.91 amu

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Electrons in an Atoms Orbit

• Electronegativity helps with the attractiveness of electrons
• The nucleus (ZEFF) has a positive charge which helps to attract negative electrons
• Columb’s Law: the relationship and distance between particles
• Adding electrons increases size and repulsion forces which need extra space: if ZEEF doesn’t change the size increases= less force

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Mass Spec

• Use isotopes and abundance values to determine what element is given
• Gas is more spread out, less attraction is formed, so more data is gathered by the spectrometer
• The mass of the isotope is determined by how many times particles hit a certain area (higher= lighter lower= heavier)

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Photoelectron Spectroscopy

• Graphs electrons and their binding energy/ ionization energy (mJ/mol)
• S: 1s2 2s2 2p6 3s2 3p4 [Xe] 3s2 3p4
• The farther the electron is away from the nucleus the weaker the bond
• Adding more electrons will increase the number of electrons and decrease the amount of binding energy on the valence shell
• More protons cause more pull in the binding energy

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