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).
Mole Definition: a chemical mass unit, defined to be 6.022 x 1023molecules, atoms, or some other unit. The mass of a mole is the gram formula mass of a substance. Examples: 1 mole of NH3 has 6.022 x 1023molecules and weighs about 17 grams. 1 mole of copper has 6.022 x 1023atoms and weighs about 63.54 grams.