Pauli exclusion principle
The principle stating that no two electrons within an atom may have an identical set of all four
quantum numbers.
Peptides
Molecules that consist of two or more amino acids linked to each other by peptide bonds.
Percent composition
The percentage of the total formula weight of a compound attributed to a given element.
Percent yield
The percentage of the theoretical product yield that is actually recovered when a chemical reaction
occurs.
Period
A horizontal row of the periodic table, containing elements with the same number of electron shells.
Periodic law
The law stating that the chemical properties of an element depend on the atomic number of the
element, and change in a periodic fashion.
Periodic table
The table displaying all known chemical elements arranged in rows (periods) and columns (groups)
according to their electronic structure.
pH
A measure of the hydrogen ion content of an aqueous solution, defined to be equal to the negative
log of the H+ concentration.