Atoms, molecules and stoichiometry: describe question

A sample of chlorine contains two isotopes, $\ce{^{35}Cl}$ and $\ce{^{37}Cl}$. The relative atomic mass of chlorine is 35.5. Describe the meanings of the following terms, using chlorine as an example where appropriate:

• unified atomic mass unit
• relative isotopic mass
• relative atomic mass
• relative molecular mass (for $\ce{Cl2}$)
• relative formula mass (for $\ce{NaCl}$)