Bohr described the hydrogen atom as an electron orbiting a hydrogen nucleus. Although certain aspects of his theory are still valid, his theory agreed quantitatively with experiment only in the case of the hydrogen atom. In what way does quantum mechanics change Bohr's original picture of the hydrogen atom?

What would you predict for the atomic number of the halogen under astatine in the periodic table?

The table below is partially completed for subshells A and B, where subshell B is the next subshell higher in energy compared to subshell A. For example, if subshell A is the $4 \mathrm{~s}$ subshell, then subshell B would be the $3 \mathrm{~d}$ subshell. Use this criteria and the information provided to complete the table.

When an electron is accelerated by a voltage difference, the kinetic energy acquired by the electron equals the voltage times the charge on the electron. Thus, one volt imparts a kinetic energy of $1.602 \times 10^{-19}$ volt-coulombs, or $1.602 \times 10^{-19} \mathrm{~J}$. What is the wavelength for electrons accelerated by $1.00 \times 10^4$ volts?

The table below is partially completed for subshells $\mathrm{A}$ and $\mathrm{B}$, where subshell $\mathrm{B}$ is the next subshell higher in energy compared to subshell A. For example, if subshell $A$ is the $4 \mathrm{~s}$ subshell, then subshell B would be the $3 \mathrm{~d}$ subshell. Use this criteria and the information provided to complete the table.

A 5.0-g sample of water starting at $60.0^{\circ} \mathrm{C} \operatorname{loses} 418 \mathrm{~J}$ of energy in the form of heat. What is the final temperature of the water after this heat loss? a. $20 .{ }^{\circ} \mathrm{C}$ b. $40 .{ }^{\circ} \mathrm{C}$ c. $50 .{ }^{\circ} \mathrm{C}$ d. $60{ }^{\circ} \mathrm{C}$ e. ${ }^{\circ} \mathrm{C}$

When an electron is accelerated by a voltage difference, the kinetic energy acquired by the electron equals the voltage times the charge on the electron. Thus, one volt imparts a kinetic energy of $1.602 \times 10^{-19}$ volt-coulombs, which equals $1.602 \times 10^{-19} \mathrm{~J}$. What is the wavelength associated with electrons accelerated by $4.00 \times 10^3$ volts?

Light with a wavelength of $405 \mathrm{~nm}$ fell on a strontium surface, and electrons were ejected. If the speed of an ejected electron is $3.36 \times 10^5 \mathrm{~m} / \mathrm{s}$, what energy was expended in removing the electron from the metal? Express the answer in joules (per electron) and in kilojoules per mole (of electrons).

What are the main divisions of the nervous system?

What is the evidence for electron waves? Give a practical application.

Sodium metal reacts with water to produce hydrogen gas in an exothermic process.

$$2 \mathrm{Na}(s)+2 \mathrm{H}_2 \mathrm{O}(l) \longrightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_2(g)$$

The reaction was carried out at $25.0^{\circ} \mathrm{C}$ and $760.0 \mathrm{mmHg}$. and the hydrogen gas generated was then collected over water at $23.0^{\circ} \mathrm{C}$ and $785 \mathrm{mmHg}$, yielding $23.1 \mathrm{~L}$ of gas. Calculate the heat evolved; use data from Appendix C.

Any object, be it a space satellite or a molecule, must attain an initial upward velocity of at least 11.2 km/s in order to escape the gravitational attraction of the earth. What would be the kinetic energy in joules of a satellite weighing 2354 lb that has the speed equal to this escape velocity of 11.2 km/s?

Light with a wavelength of $425 \mathrm{~nm}$ fell on a potassium surface, and electrons were ejected at a speed of $4.88 \times 10^5 \mathrm{~m} / \mathrm{s}$. What energy was expended in removing an electron from the metal? Express the answer in joules (per electron) and in kilojoules per mole (of electrons).

When ice at $0^\circ C$ melts to liquid water at $0^\circ C$, it absorbs 0.334 kJ of heat per gram. Suppose the heat needed to melt 31.5 g of ice is absorbed from the water contained in a glass. If this water has a mass of 0.210 kg and a temperature of $21.0^\circ C$, what is the final temperature of the water? (Note that you will also have 31.5 g of water at $0^\circ C$ from the ice.)