Explain the operation of a cathode-ray tube. Describe the deflection of cathode rays by electrically charged plates placed within the cathode-ray tube. What does this imply about cathode rays?

Do the proton and the neutron have exactly the same mass? How do the masses of the proton and neutron compare to the mass of the electron? Which particles make the greatest contribution to the mass of an atom? Which particles make the greatest contribution to the chemical properties of an atom?

2-31 Tin-118 is one of the isotopes of tin. Name the isotopes of tin that contain two, three, and six more neutrons than tin-118.

Give the atomic number (Z) and the mass number (A) for each of the following: a. a carbon atom with 8 neutrons b. an aluminum atom with 14 neutrons c. an argon atom with 20 neutrons d. a copper atom with 36 neutrons

2.86 For some uses, the relative abundance of isotopes must be manipulated. For example, a medical technique called boron neutron capture therapy needs a higher fraction of 10B than occurs naturally to achieve its best efficiency. What would happen to the atomic weight of a sample of boron that had been enriched in 10B? Explain your answer in terms of the concept of a weighted average.

What evidence led to the conclusion that cathode rays had a negative charge?

Though the common isotope of aluminum has a mass number of 27, isotopes of aluminum have been isolated (or prepared in nuclear reactors) with mass numbers of 24, 25, 26, 28, 29, and 30. How many neutrons are present in each of these isotopes? Why are they all considered aluminum atoms, even though they differ greatly in mass? Write the atomic symbol for each isotope.

The vitamin niacin (nicotinic acid,C6H5NO2 ) can he isolated from a variety of natural sources, such as liver, yeast, milk, and whole grain. It also can be synthesized from commercially available materials. Which Source of nicotinic acid, from a nutritional view, is best for use in a multivitamin tablet? Why?