91Ó°ÊÓ

What else besides an atom's mass number would you need to determine its elemental identity? Explain how you would use it along with the mass number.

Does knowing how many electrons a neutral atom has tell you its elemental identity? Explain.

Physicists are fond of saying that an atom is mostly empty space. What justifies this statement?

Fill in the following table for four neutral atoms: $$ \begin{array}{lcccc} & { }_{8}^{15} \mathrm{O} & ? & ? & ? \\ \hline \text { Mass number } & ? & 16 & 37 & ? \\ \text { Atomic number } & ? & 8 & ? & ? \\ \text { Number of protons } & ? & ? & ? & ? \\ \text { Number of neutrons } & ? & ? & ? & 12 \\ \text { Number of electrons } & ? & ? & 17 & 11 \\ \hline \end{array} $$

Uranium exists mainly as two isotopes in nature, possessing mass numbers 235 and 238 . Write the full atomic symbols for both isotopes.

Write the full atomic symbol for the only atom that has its mass number equal to its atomic number.

What is the difference between an atom's atomic mass and its mass number?

Why is the atomic mass scale also called the relative atomic mass scale?

How much more massive is an "average" titanium (Ti) atom than a \({ }_{6}^{12} \mathrm{C}\) atom? (Use the periodic table for the atomic mass of titanium.)

How much more massive is an "average" oxygen atom than a He atom? (Use the atomic masses from the periodic table.)