Counting Atoms-The Mole, Atomic Mass, Formula Mass, and Molar Mass

Atomic Mass

the mass of an atom of a chemical element expressed in atomic mass units (amus)

Formula mass

The sum of the atomic masses of all the elements present in a compound expressed in AMUs (Found by added together the masses of the elements)

Molecular mass

The sum of the atomic masses of all the elements present in a molecule expressed in AMUs (Found by added together the masses of the elements)

What is molar mass?

The formula mass expressed in grams/mol (same as formula mass just in grams/mol)

Mole

Describes the amount and mass of atoms present in a chemical sample or Avogadro's number 6.02 x 10^23

Mole

Mass of an atom (in amu's) relative to the mass of the carbon-12 atom

the isotope used to standardize the value of the mole

carbon-12

Avogadro's #

6.02x10²³

1 mole of any element has

6.02 x 10²³ atoms

1 mole of any particle has

6.02 x 10²³ particles (particles can be atoms, ions, formula units, or molecules)

Molar mass

determined by adding the mass of the element(s) on periodic table for the element or compound, in g/mol

Molar mass of a molecule

atomic mass for each element in the molecule added together for all elements in the compound in g/mol

What are the steps for finding the formula mass and molecular mass?

1. How many of each element?

2. Find atomic mass for each element

3. Multiply mass by number of atoms of that element

4. Repeat for all elements

5. Add total mass for each to determine the formulas mass

6. Express in AMUs depending on what its asking for

What are the steps for finding the molar mass?

1. How many of each element?

2. Find atomic mass for each element

3. Multiply mass by number of atoms of that element

4. Repeat for all elements

5. Add total mass for each to determine the formulas mass

6. Express in g/mol depending on what its asking for

What is the molecular mass of Cl₂?

71.0 amu

What is the molar mass of H₂SO₄?

98.0 g/mol

What is the molar mass of F₂?

38.0 g/mol

What is the formula mass of H₂SO₃?

81.0 amu

What is the molar mass of Na?

23.0 g/mol

What is the atomic mass of Li?

7.0 amu

What is the molar mass of NaCl?

58.5 g/mol

What is the formula mass of Ca(OH)₂?

74.0 amu

What is the molar mass of MgO?

40.0 g/mol

What is the formula mass of O₂?

32.0 amu

What is the molar mass of NaBr?

103.0 g/mol

What is the molar mass of Cl₂?

71.0 g/mol

What is the atomic mass of Mg?

24.3 amu

What is the molar mass of CuCO₃?

123.5 g/mol

What is the molar mass of Be?

9.0 g/mol

What is the atomic mass of C?

12.0 amu

What is the molar mass of N?

14.0 g/mol

What is the atomic mass of He?

4.0 amu

What is the molar mass of Ar?

40.0 g/mol

What is the molar mass of Li₂O?

30.0 g/mol

What is the formula mass of Ca₃(PO₄)₂?

310.3 amu

What are the 4 different types of particles?

1. atoms

2. ions

3. formula units (for ionic compounds)

4. molecules