To convert grams to atoms:
1) First, you transform grams into moles using the atomic mass of the element.
2) Transform moles into atoms using the avogrado's constant
So:
1) The atomic mass of potassium is 39.1 amu (look for it on the periodic table). This means that 1 mole of potassium has 39.1 g of potassium.
You have 1.78 grams of potassium.
1 mole of potassium ---- 39.1 g of potassium
x mol of potassium ---- 1.78 g of potassium
39.1x = 1.78
x = 1.78/39.1
x = 0.0455 moles of potassium
2) Avogrado's constant is 6.022 × 10²³ atoms = 1 mol
6.022 × 10²³ atoms ----- 1 mol
x atoms ---- 0.0455 mol
x = 2.7415 × 10²² atoms of potassium
Answer: 2.7415 × 10²² atoms of potassium
