Question

For each of these Lewis symbols, indicate the group in the periodic table in which the element \(X\) belongs: (a) \(\cdot \dot{\mathrm{X}} \cdot(\mathrm{b}) \cdot \mathrm{X} \cdot(\mathrm{c}): \dot{\mathrm{X}}\)

Short answer

In the given Lewis symbols, the element X belongs to the following groups in the periodic table: (a) Group 13 with 3 valence electrons, (b) Group 2 with 2 valence electrons, and (c) Group 1 with 1 valence electron.

Step-by-step solution

Identify the number of valence electrons for each Lewis symbol

Determine the number of valence electrons by counting the dots around element X in each scenario: (a) \(\cdot \dot{\mathrm{X}} \cdot\) : 3 valence electrons (b) \(\cdot \mathrm{X} \cdot\) : 2 valence electrons (c) \(\dot{\mathrm{X}}\) : 1 valence electron

Match each scenario to the correct group in the periodic table

Determine the group in the periodic table in which element X belongs for each scenario: (a) 3 valence electrons: Element X belongs to Group 13. (b) 2 valence electrons: Element X belongs to Group 2. (c) 1 valence electron: Element X belongs to Group 1.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom. These electrons play a pivotal role in chemical bonding and reactions. When we refer to valence electrons, we are specifically talking about how these electrons participate in forming chemical bonds. Typically, the number of valence electrons is equal to an element's main group number in the periodic table, which makes understanding their behavior easier.
In Lewis symbols, valence electrons are represented as dots around an element’s symbol. By counting these dots, you can easily determine how many valence electrons are present. For instance:

• A Lewis symbol with three dots means three valence electrons.


• One with two dots indicates two valence electrons.


• If there's a single dot, this represents one valence electron.

Understanding valence electrons is crucial as they dictate how an element will interact with others. They determine the element’s chemical properties and its placement in the periodic table.

Periodic Table Groups

The periodic table is organized into groups, which are the columns of the table. Elements in the same group have similar properties and valence electron configurations. This simplifies predicting an element’s chemical behavior.
The Lewis symbols with different valence electrons help identify to which group on the periodic table an element belongs:

• If an element has 1 valence electron, like \,dot{X} \,\, \(\dot{X}\), it belongs to Group 1, the alkali metals.


• Two valence electrons, such as in \,\, \, \cdot{X}\cdot \,\, \(\cdot \mathrm{X} \cdot\), correspond to Group 2, the alkaline earth metals.


• Elements with three valence electrons, like \,\, \,\cdot{\dot{X}}\cdot \,\, \(\cdot \dot\mathrm{X} \cdot\), fall into Group 13, also known as the boron group.

Using periodic table groups helps in understanding how elements will bond and their general reactivity, making chemistry much simpler and systematic.

Element Classification

Element classification refers to how we organize elements based on their properties and behaviors. In chemistry, elements are grouped into metals, nonmetals, and metalloids. Additionally, we look at categories like transition metals and inner transition metals.
Knowing the number of valence electrons of an element allows us to classify them accurately. Metals generally have fewer valence electrons, often making them good conductors and very reactive, like the alkali metals in Group 1.
Nonmetals tend to have more valence electrons, causing them to react differently, often by gaining or sharing electrons. For example, the three dots in a Lewis symbol indicating three valence electrons would be characteristic of metalloids, like those in Group 13. Metalloids exhibit properties of both metals and nonmetals, making them unique and versatile.

• Elements with fewer valence electrons often donate or lose electrons easily.


• Those with more tend to gain or share electrons to reach a stable electron configuration.

By understanding element classification and how valence electrons contribute to this, students can predict how elements will behave in chemical reactions, aiding in both academic and practical applications of chemistry.