- 62 Views
- Uploaded on
- Presentation posted in: General

Atomic Calculations and Mass Spectrometry

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Atomic Calculations and Mass Spectrometry

Quantum Orbital Video

Atomic Mass – Atomic Number = # Neutrons

(p + n) - (p) = (n)

110

Complete the following chart:

protonselectronsneutrons

H

Zr

Ca2+

P3-

Al3+

Cl-

404051

201820

151816

131014

171819

Isotopes- same atomic number but different mass

For example, there are 3 types of hydrogen atoms.

1H 2H 3H

Not all atoms of the same element are identical.

Mass Spectrometers

Are used to determine the abundance and mass of the isotopes of elements

Mass Spectrometers

A device known as a mass spectrometercan be used to determine the relative abundanceand the mass of the isotopes of elements.

In the graph the isotopes of a sample of the element zirconium can be seen in their relative abundances.

The data can be summarized as follows:

IsotopeMass`Abundance

90Zr90.00 amu 51.5 %

91Zr91.00 amu 11.2 %

92Zr92.00 amu 17.1 %

94Zr94.00 amu 17.4 %

96Zr96.00 amu 2.80 %

atomic mass of isotope 100 %

Calculate the weighted average mass of zirconium using the data above.

Change each percent to a decimal by dividing by 100.

Multiply by the mass.

Add it all together.

0.515(90.00)

+ 0.112(91.00)

+ 0.171(92.00)

+ 0.174(94.00)

+ 0.0280(96.00)

=91.3 amu

3 sig figs!

Look up the mass on the periodic chart.

The unit amu describes how many times heavier than the mass of H

=91.2 amu

They are the same with uncertainty

Calculate the average atomic mass for Germanium

36.54 %

73.92115 amu

27.43 %

71.92174 amu

20.52 %

69.92428 amu

7.76 %

75.9214 amu

7.76 %

72.9234 amu

(0.2052)(69.92428) + (0.2743)(71.92174) + (0.0776)(72.9234) + (0.3654)(73.92115) + (0.0776)(75.9214) =

=72.6 amu

Periodic Table=72.6 amu

Quantum orbitals