Who discovered the nucleus? Describe the experiment that led to this discovery.

It is good practice to actively read the textbook and to try to verify claims that are made when you can. The following claim is made in your textbook: “. . . if the nucleus were the size of a grape, the electrons would be about 1 mile away on average.” Provide mathematical support for this statement.

Read the Chemistry in Focus” segment “Whair”Do You Live? How can isotopes he used to identify the general region of a person’s place of residence?

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.

An element consists of 1.40% of an isotope with mass 203.973 u, 24.10% of an isotope with mass 205.9745 u, 22.10% of an isotope with mass 206.9759 u, and 52.40% of an isotope with mass 207.Y766 u. Calculate the average atomic mass, and identify the element.

. The elements with atomic numbers of 93 or greater are referred to as the _________ elements.

Radon is a radioactive gas that can cause lung cancer. It has been detected in the basement of some homes. In an atom of Rn-220, (a) how many protons are there? (b) how many neutrons are there?

How do isotopes of a given element differ? How are they similar?

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.