2.4-2.6

2.4: The Masses of Atoms, Ions, and Molecules:

Average atomic mass: the weighted average of the masses of all isotopes of an element, calculated by multiplying the natural abundance of each isotope by its mass in unified atomic mass units and then summing the products
Natural Abundances: the proportion of a particular isotope, usually expressed as a percentage, relative to all the isotopes of that element in a natural sample
Mass spectrometers: an analytical instrument for determining the chemical composition of samples by ionizing them and then separating the ions based on their mass (m) to charge (z) ratios
Molecular mass: the sum of the average atomic masses of the atoms that are chemically bonded together in it
Formula unit: the smallest electrically neutral unit of an ionic compound
Formula mass: the sum of the average atomic masses of the cations and the anions that make up a neutral formula unit

mole (mol): SI base unit for expressing quantities of substances
Avogadro constant, NA: the number of elementary entities-atoms, ions, or molecules-in 1 mole of a substance
- 6.02214076×10²³ mol^-1
Mole serves as the link between atomic mass values on the periodic table and measurable masses of elements and compounds
Molar mass (M): the mass of 1 mole of a substance
- same between atomic mass, mol, and molar mass

In mass spectrometers, sample molecules are converted into ions that are then separated according to the ratio of their masses (m) to their electrical charges (z)
Molecular ion (M+): an ion formed in a mass spectrometer when a molecule loses an electron after being bombarded with high-energy electrons. The molecular ion has a charge of 1+ and has essentially the same molecular mass as the molecule form which it came.
Mass spectrum: a graph of data from a mass spectrometer featuring peaks whose heights are measures of the numbers of ions of different masses produced from an ample in the spectrometer’s ion source