Problem 73 - 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: Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). These elements are all in the same group, Group 1, also known as alkali metals. They share similar chemical properties, being highly reactive and forming +1 ions, due to having one valence electron.

Step 1: Understanding Lewis Symbols

A Lewis symbol represents an atom, and specifically, its valence electrons (the electrons in the outermost shell). Lewis symbols consist of the chemical symbol of the element surrounded by dots representing valence electrons. The number of dots around the symbol is equal to the number of valence electrons an element has.

Step 2: Identifying elements with a single dot in their Lewis symbols

Since we are looking for Lewis symbols with a single dot, this means that these elements have only one valence electron. Elements have increasing numbers of valence electrons as we move from left to right across a period. In the first and second periods (rows) of the periodic table, we can find elements in the first group (column), also known as alkali metals, which have one valence electron. These elements are: 1. Hydrogen (H) 2. Lithium (Li) 3. Sodium (Na) 4. Potassium (K) 5. Rubidium (Rb) 6. Cesium (Cs) 7. Francium (Fr)

Step 3: Determining if these elements are in the same group and explain

All these elements with a single dot in their Lewis symbols are found in Group 1 of the periodic table, also known as alkali metals. This group is defined by elements having one valence electron. Elements in the same group share similar chemical properties, and in the case of alkali metals, they are highly reactive and form +1 ions. Hence, the elements represented by a Lewis symbol with a single dot are indeed in the same group, called the alkali metals.