Problem 77 - Chemistry The Central Science

Question

How many elements in the periodic table are represented by a Lewis symbol with a single dot? Are all these elements in the same group? Explain.

Step-by-Step Solution

Answer

There are 7 elements in the periodic table represented by a Lewis symbol with a single dot, and all these elements belong to the same group, Group 1 (alkali metals).

Step 1: Understanding Lewis Symbols

Lewis symbols show the valence electrons of an element as dots placed around the chemical symbol of the element. For example, hydrogen has one valence electron, so its Lewis symbol is H with one dot next to it: H •

Step 2: Identifying Elements with a Single Dot in Their Lewis Symbol

Elements with a single dot in their Lewis symbol have one valence electron. In the periodic table, elements in group 1 (also known as alkali metals) have one valence electron. Group 1 elements are Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). Therefore, there are 7 elements in the periodic table with a single dot in their Lewis symbol.

Step 3: Check if all Elements Belong to the Same Group

All the elements with one valence electron, as mentioned above, belong to Group 1 of the periodic table (alkali metals). Therefore, all the elements with a single dot in their Lewis symbol belong to the same group. In conclusion, there are 7 elements in the periodic table represented by a Lewis symbol with a single dot, and all these elements belong to the same group, Group 1 (alkali metals).

Key Concepts

Valence Electrons

Valence electrons are the electrons that are located in the outermost shell of an atom. They are crucial because they determine how an atom will react with others. The number of valence electrons influences an atom's bonding behavior. For instance, elements with the same number of valence electrons often have similar chemical properties.

Valence electrons are represented in Lewis symbols, which provide a simple way to visualize them. A Lewis symbol includes the element's symbol surrounded by dots that represent its valence electrons. For example, the Lewis symbol for oxygen, which has six valence electrons, would be "O" surrounded by six dots. It helps to quickly identify how many electrons are available for potential chemical bonding.

Alkali Metals

Alkali metals are found in Group 1 of the periodic table. This group includes elements such as lithium (Li), sodium (Na), potassium (K), and others. They all have one valence electron, which makes them highly reactive. This single electron is loosely held, making it easy for these elements to lose it and form positive ions during chemical reactions.

Because of their reactivity, alkali metals are never found in their pure form in nature; they are usually combined with other elements. They react vigorously with water to form hydroxides and release hydrogen gas. Their readiness to donate their lone valence electron explains this behavior, as they strive to achieve a stable electron configuration.

Periodic Table Groups

The periodic table is organized into groups and periods that help predict the properties of elements. Groups are the vertical columns, numbered from 1 to 18. Elements in the same group share similar chemical properties because they have the same number of valence electrons. This key feature allows for easy prediction of how an element will react chemically.

Group 1 elements, known as alkali metals, all have one valence electron, as previously mentioned, and are thus grouped together. Understanding these groupings helps chemists and students predict an element's behavior, how it might bond, and its reactivity. So, learning about periodic table groups enhances our ability to understand the vast number of elements efficiently.