Unit 1 AOS 2 - How Are Materials Quantified and Classified?

What is an isotope?

• Atoms of the same element that have different mass due to ta different number of neutrons

• Have the same number of protons

What is mass spectrometry?

• An analytical technique used to measure the mass of ions relative to their charge

What is mass-to-charge ratio (m/z)?

• The mass of an ion divided by its charge

What is the molecular formula?

• The actual number of atoms in a molecule

What is relative abundance?

• The percentage of a particular isotope found in a naturally occuring sample of an element

What is the relative atomic mass (A_^r)?

• The weighted average of the masses of an element’s isotopes on a scale on which a carbon-12 atom is assigned a value of 12 exactly

What is the relative formula mass? (M_r)?

• The weighted aaverage of a substance’s masses of the formula units on a scale on which the mass of a carbon-12 atom is assigned a value of 12 exactly

What is the relative isotopic mass?

• The mass of the isotope on the scale in which the relative isotopic mass of the caron-12 atom is assigned a value of 12 exactly

What is the relative molecular mass (M_r)?

• The weighted average of a molecule’s masses of the formula units on a scale on which the mass of a carbon-12 atom is assigned a value of 12 exactly.

What is the formula for the relative atomic mass (A_r)?

A_r = (relative abundance % x relative isotopic mass) + (relative abundance % x relative isotopic mass)/ 100

What are the units for relative atomic mass (A_r)?

amu