# Counting Atoms

## 17 terms

### atomic number

(Z) of an element is the number of protons in the nucleus of each atom of that element

### isotopes

atoms of the same element that have different masses

### mass number

total number of protons and neutron in the nucleus of an isotope

### hyphen notation

name of the element-mass number

### nuclide

general term for any isotope of any element

### atomic mass unit

amu, exactly 1/12 the mass of a carbon-12 atom, or 1.660 540 x 10^ -23

### average attomic mass

the weighted average of the stomic masses of the naturally occuring isotopes of an element

### mole

the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12

6.022 1367 x 10^23-is the number of particles in exactly one mole of a pure substance, 6.022 x 10^23

### mole

(mol) the amount of a substance that contains Avogadro's number of particles

### molar mass

the mass of one mole of a pure substance

### moles to atoms

multiply __________ by Avogadro's # =_________

### moles to grams

multiply __________by molar mass of element=________

### atoms to grams

multiply 1/Avogadros' # by the molar mass of the element=________

### grams to moles

multiply _______________by 1/molar mass of element

### grams to atoms

multiply ______________by 1/molar mass of element by Avogadro's # = _________

### atoms to moles

multiply __________ by 1/Avogadro's # = _______________