What is the energy of the $\alpha$ particle emitted in the decay ${ }^{2104} \mathrm{Po} \rightarrow{ }^{206} \mathrm{~Pb}+\alpha$ ? Take into account the recoil of the daughter nucleus.

In a helium atom, which contains two electrons, do you think that on average the electrons are closer to the nucleus or farther away than in a hydrogen atom? Why?

Natural aluminum is all $_{13}^{27} \mathrm{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^{+}$ or $\beta^{-} ?$ What will be the product nucleus?

Describe how eukaryotic cells are able to keep such large amounts of DNA in the small volume of the cell nucleus. (Hint Review the structure of a chromosome in Chapter 10.)

Show that the magnetic dipole moment M of an electron orbiting the proton nucleus of a hydrogen atom is related to the orbital momentum $L$ of the electron by

$$M=\frac{e}{2 m} L.$$

When a nucleus undergoes either $\beta^{-}$ or $\beta^{+}$ decay, what happens to the energy levels of the atomic electrons? What is likely to happen to these electrons following the decay?

A nucleus with mass number $A=182$ and atomic number $Z=74$ loses two neutrons. What are the resulting (a) mass number, (b) atomic number, and ( c) neutron number?

Near the surface of the nucleus of a lead atom, the electric field has a strength of $3.4 \times 10^{21} \mathrm{~V} / \mathrm{m}$. What is the energy density in this field?

Match each term on the left with its meaning on the right.

$$\begin{aligned} \text{proximal}\qquad \qquad \qquad\quad & \text{a. pertaining to the sole of the foot}\\ &\text{b. tail bone}\\ &\text{c. ventral cavity that contains heart, lungs, and associated structures}\\ &\text{d. toward the surface of the body (external)}\\ &\text{e. lying horizontal with face downward}\\ &\text{f. turning outward}\\ &\text{g. nearer to the center (trunk of the body)}\\ &\text{h. ventral cavity that contains digestive, reproductive, and excretory structures}\\ &\text{i. turning inward or inside out}\\ &\text{j. part of the spine known as the neck}\\ &\text{k. movement toward the median plane}\\ &\text{l. away from the head; toward the tail or lower part of a structure}\\ &\text{m. away from the surface of the body (internal)}\\ &\text{n. part of the spine known as the loin}\\ &\text{o. near the back of the body}\\ \end{aligned}$$

A nucleus of 4 neutrons and 4 protons that is surrounded by 2 orbiting electrons is

(a) a positive ion.

(b) a negative ion.

(c ) an alpha particle

(d) a beta particle

In a helium atom, which contains two electrons, do you think that on average the electrons are closer to the nucleus or farther away than in a hydrogen atom? Why?

Calculate the mass defect for the neon-20 nucleus. The mass of neon-20 is $19.992440 ~u$. (Hint: How many protons and neutrons does neon-20 have?)

What is the electric potential energy of a system that consists of two protons $2.5 \times 10^{-15} \mathrm{m}$ apart-as might occur inside a typical nucleus?

Give the number of protons and number of neutrons in the nucleus of each of the following: (16.1) a. boron-10 b. zinc-72 c. iron- 59 d. gold-198