A sample of barium contains 3.20g of barium. How many atoms of barium are contained in the sample?

How many mols do you have? That's mols = grams/molar mass = approx 0.023 but you need to do it more accurately.

Then 1 mol contains 6.02E23 atoms. So 0.023 mols will contain ...... atoms.

To determine the number of atoms of barium in the sample, we need to use the concept of molar mass and Avogadro's number.

Step 1: Find the molar mass of barium (Ba)
The molar mass of barium can be found by referring to the periodic table. The atomic weight of Ba is approximately 137.33 g/mol.

Step 2: Calculate the number of moles of barium in the sample
To find the number of moles, we need to divide the mass of the sample (3.20g) by the molar mass of barium (137.33 g/mol):
Number of moles = Mass of sample (g) / Molar mass (g/mol)
Number of moles = 3.20g / 137.33 g/mol = 0.023 mol

Step 3: Use Avogadro's number to find the number of atoms
Avogadro's number, 6.022 × 10^23, corresponds to the number of particles (atoms, molecules) in one mole of a substance.

To determine the number of atoms of barium in the sample, multiply the number of moles by Avogadro's number:
Number of atoms = Number of moles × Avogadro's number
Number of atoms = 0.023 mol × 6.022 × 10^23/mol = 1.39 × 10^22 atoms

Therefore, there are approximately 1.39 × 10^22 atoms of barium in the sample.