The electron configurations described in this chapter all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations: (a) $1s^12s^1$
(b) $1s^22s^22p^23d^1$ (c) $1s^22s^22p^64s^1$ (d) $[\mathrm{Ar}]4s^13d^{10}4p^4$ (e) $[\mathrm{Ne}]3s^23p^43d^1$

Find the area of the regular hexagon of side 8 in. Round the result to two decimal places.

According to survey records, $75.4 \%$ of women aged 20-24 have never been married. In a random sample of 250 young women aged $20-24$, determine the mean, variance, and standard deviation for the number who are or who have been married.

Find the average for each group.

$$2.4,3.5,4.7,2.9,8.4$$

In a group, discuss and compare your responses.

When the principal quantum number is n = 4, how many different values of l, are possible?

Find the average for each group.

$$526,387,431,388$$

The electron configurations described in Chapter 2 all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations:

$$1 s^2 2 s^2 2 p^6 4 s^1$$

The following data were obtained for repetitive weighings of a $1.004$-g standard weight on a top-loading balance:

$$\begin{array}{lll}1.003 & 1.000 & 1.001 \\ 1.004 & 1.005 & 1.006 \\ 1.001 & 0.999 & 1.007\end{array}$$

(a) Assuming the noise is random, calculate the signal-to-noise ratio for the balance.

(b) How many measurements would have to be averaged to obtain a $S / N$ of $500$?

Find the average for each group.

$$1.4,2.5,4.8,3.7,2.0,3.9$$

Solve using special triangles. Answer in both exact and approximate form. A heavy-duty ramp is used to winch heavy appliances from street level up to a warehouse loading dock. If the ramp is $7.5\ \mathrm{ft}$ high and the incline is $15\ \mathrm{ft}$ long, (a) what angle $\alpha$ does the dock make with the street? (b) How long is the base of the ramp?

For each of the terms below, write a sentence explaining how it relates to the New Deal era.

New Deal

The electron configurations described in this chapter all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations: (e) $[\mathrm{Ne}] 3 s^2 3 p^4 3 d^1$

Draw the R group of
(c) methionine