Her behavior has been reinforced (i.e. strengthened). Reinforcement can be external or internal and can be positive or negative. If a child wants approval from parents or peers, this approval is an external reinforcement, but feeling happy about being approved of is an internal reinforcement.
It remained to define the unit of amount of substance by fixing the corresponding mass of carbon 12; by international agreement, this mass has been fixed at 0.012 kg, and the unit of the quantity amount of substance was given the name mole (symbol mol).
A mole is a unit of measure based on Avogadroâs Law or the Avogadro constant. The specific number of molecules in one gram-mole of a substance, defined as the molecular weight in grams, is 6.022140857 Ã 10(23), a quantity called Avogadroâs number, or the Avogadro constant. For example, the molecular weight of oxygen is 32.00, so that one gram-mole of oxygen has a mass of 32.00 grams and contains 6.022140857 Ã 10(23)molecules.