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).
Etymology: L, molecula, small mass. the standard unit used to measure the amount of a substance. A mole of a substance is the amount containing the same number of elementary particles as there are atoms in 12 g of carbon 12, typically 6.02 Ã 1023 particles. This number is called Avogadro's number. Also spelled mol.