Without consulting Figure 2.6 or Table 2.2, determine...

Without consulting Figure $2.6$ or Table $2.2$, determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices. (a) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{7} 4 s^{2}$ (b) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}$ (c) $1 s^{2} 2 s^{2} 2 p^{5}$ (d) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2}$ (e) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{2} 4 s^{2}$ (f) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{1}$

Without consulting Figure $2.6$ or Table $2.2$, determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices.
(a) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{7} 4 s^{2}$
(b) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}$
(c) $1 s^{2} 2 s^{2} 2 p^{5}$
(d) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2}$
(e) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{2} 4 s^{2}$
(f) $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{1}$

Key Concepts

Electron Configuration

Electron configuration describes the distribution of electrons among an atom’s orbitals, structured by increasing energy levels according to principles like the Aufbau principle, the Pauli exclusion principle, and Hund’s rule. This concept is foundational for understanding why elements exhibit certain chemical and physical properties.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that participate in chemical bonding and determine an element’s reactivity. Their number and arrangement directly influence an element's placement in the periodic table and its classification into groups such as alkali metals, alkaline earth metals, and halogens.

Periodic Table Classification

The periodic table is organized so that elements with similar electron configurations, particularly in their outer shells, are grouped together. This grouping leads to recurring chemical properties and helps in classifying elements as inert gases, alkali metals, alkaline earth metals, halogens, or transition metals, among others.

Group-specific Electron Configurations

Different groups of elements exhibit characteristic electron configurations in their valence shells. For instance, alkali metals typically have one electron in their outermost s orbital, alkaline earth metals have two, halogens have seven (almost completing an octet), and inert gases have fully filled valence shells. Recognizing these patterns allows for the identification of an element’s group solely based on its electron configuration.

Transition Metals

Transition metals are characterized by the presence of electrons in d orbitals in addition to their s electrons. This unique electron configuration results in properties like variable oxidation states, complex ion formation, and catalytic activity, distinguishing them from the s- and p-block elements.

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