What percent of the total mass of one atom of each of the following elements comes from protons?

(a) selenium (mass of one atom $=1.311 \times 10^{-22} \mathrm{~g}$ )
(b) xenon (mass of one atom $=2.180 \times 10^{-22} \mathrm{~g}$ )
(c) chlorine (mass of one atom $=5.887 \times 10^{-23} \mathrm{~g}$ )
(d) barium (mass of one atom $=2.280 \times 10^{-22} \mathrm{~g}$ )

The ferricyanide ion has the formula $\mathrm{Fe}(\mathrm{CN})_6^{3-}$. Write the formula for the compounds that ferricyanide would form with the cations of elements 3,13, and 30.

What experimental evidence supports these statements?

(a) The nucleus of an atom is small.
(b) The atom consists of both positive and negative charges.
(c) The nucleus of the atom is positive.

What are the atomic numbers of (a) copper, (b) nitrogen, (c) phosphorus, (d) radium, and (e) zinc?

An aluminum atom has an average diameter of about $3.0 \times 10^{-8} \mathrm{~cm}$. The nucleus has a diameter of about $2.0 \times 10^{-13} \mathrm{~cm}$. Calculate the ratio of the atom's diameter to its nucleus.

A particular element exists in two stable isotopic forms. One isotope has a mass of $34.9689$ amu. The other isotope has a mass of $36.9659\mathrm{~amu}$. Calculate the average mass of the element and determine its identity.

What is the nuclear composition of the five naturally occurring isotopes of germanium having mass numbers $70,72,73,74$, and $76$?

Naturally occurring zirconium exists as five stable isotopes: ${ }^{90} \mathrm{Zr}$ with a mass of $89.905$ amu (51.45%); ${ }^{91} \mathrm{Zr}$ with a mass of $90.906 \mathrm{~amu}(11.22 \%)$ ) ${ }^{92} \mathrm{Zr}$ with a mass of $91.905 \mathrm{~amu}$ (17.15%); ${ }^{94} \mathrm{Zr}$ with a mass of $93.906$ amu (17.38%); and ${ }^{96} \mathrm{Zr}$ with a mass of $95.908 \mathrm{~amu}(2.80 \%)$. Calculate the average mass of zirconium.

A particular element exists in two stable isotopic forms. One isotope has a mass of $62.9296 \mathrm{~amu}$. The other isotope has a mass of $64.9278 \mathrm{~amu}$. Calculate the average mass of the element and determine its identity.

An average dimension for the radius of an atom is $1.0\times 10^{-8}\mathrm{~cm}$, and the average radius of the nucleus is $1.0\times 10^{-13}\mathrm{~cm}$. Determine the ratio of atomic volume to nuclear volume. Assume that the atom is spherical.

A mole of helium gas contains $6.02 \times 10^{23}$ helium atoms. How many helium atoms are there in a micromole of helium? How many moles of helium does $1.25 \times 10^{20}$ atoms of helium represent?

How is it possible for there to be more than one kind of atom of the same element?

You decide to go sailing in the tropics with some friends. Once there, you listen to the marine forecast, which predicts inshore wave heights of $1.5\mathrm{~m}$, offshore wave heights of $4\mathrm{~m}$, and temperature of $27^{\circ}\mathrm{C}$. Your friend the captain is unfamiliar with the metric system, and he needs to know whether it is safe for your small boat and if it will be warm. He asks you to convert the measurements to feet and Fahrenheit, respectively.

What is the electric charge of a proton?