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:
$1 s^2 2 s^2 2 p^2 3 d^1$.

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 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:
$1 s^1 2 s^1$.

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) $1 s^1 2 s^1$

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) $[\mathrm{Ne}] 3 s^2 3 p^4 3 d^1$

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:

$$[\operatorname{Ar}] 4 s^1 3 d^{10} 4 p^4$$

Arrange the elements in each of the following groups in increasing order of most positive electron affinity:
$\mathrm{F}, \mathrm{Cl}, \mathrm{Br}$, and $\mathrm{I}$.

Arrange the elements in each of these groups in order of increasing electron affinity: (a) $\mathrm{Li, Na, K}$; (b) $\mathrm{F, Cl, Br, I}$.

Arrange the elements in each of the following groups in order of increasing electron affinity: (a) Li, Na, K; (b) F, Cl, Br, I.

On the basis of their positions in the periodic table, select the atom with the larger atomic radius in the pair: Na, Cs.

On the basis of their positions in the periodic table, select the atom with the larger atomic radius in each of these pairs: (a) $\mathrm{Na}$, $\mathrm{Cs}$; (b) $\mathrm{Be}$, $\mathrm{Ba}$; (c) $\mathrm{N}, \mathrm{Sb}$; (d) $\mathrm{F}, \mathrm{Br}$ ; (e) $\mathrm{Ne}, \mathrm{Xe}$.

On the basis of their positions in the periodic table, select the atom with the larger atomic radius in each of the following pairs: (a) Na, Cs; (b) Be, Ba; (c) N, Sb; (d) F, Br; (e) Ne, Xe.

On the basis of their positions in the periodic table, select the atom with the larger atomic radius in each of the following pairs: (a) Na, Si; (b) Ba, Be; (c) N, F; (d) Br, Cl; (e) Ne, Kr.

Calculate the frequency (Hz) and wavelength (nm) of the emitted photon when an electron drops from the $n=4$ to the $n=3$ level in a hydrogen atom.