A compound is a pure substance made up of two or more different atoms joined by chemical bonds. Consider the composition of the air in Earth’s atmosphere. Which of the components of air is a compound? (Hint: refer back to your elements notes) How do you know?

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.

Use the periodic table to find the molar mass of each element. molar mass h = g/mol molar mass s = g/mol molar mass o = g/mol

How many moles are in 1.26*10^24 particles in significant figures