Problem 27 - Chemistry The Science in Context

Question

Draw Lewis symbols of atoms of lithium, magnesium, and aluminum.

Step-by-Step Solution

Answer

Answer: The Lewis symbols for lithium (Li), magnesium (Mg), and aluminum (Al) are Li•, Mg••, and Al with 3 dots arranged around it as follows: Al • ••••

Step 1: Determine the number of valence electrons for each atom

To determine the number of valence electrons for each atom, we need to look at the periodic table and find out the group number for each element. Elements in the same group have the same number of valence electrons. Lithium (Li) is in Group 1, so it has 1 valence electron. Magnesium (Mg) is in Group 2, so it has 2 valence electrons. Aluminum (Al) is in Group 13, so it has 3 valence electrons.

Step 2: Draw the Lewis symbols

Lewis symbols are a way to represent the valence electrons of an element using dots around the chemical symbol. To do this, we will place the appropriate number of dots around each element's chemical symbol based on the number of valence electrons determined in Step 1. - Lithium (Li): Place 1 dot around the symbol Li, since it has 1 valence electron. Lewis symbol: Li• - Magnesium (Mg): Place 2 dots around the symbol Mg, since it has 2 valence electrons. Lewis symbol: Mg•• - Aluminum (Al): Place 3 dots around the symbol Al, since it has 3 valence electrons. Arrange the dots evenly with one dot on the top, one on the right, and one on the bottom. Lewis symbol: Al • ••••

Key Concepts

Valence Electrons

Valence electrons are the electrons located in the outermost shell of an atom. They play a vital role in determining an atom's ability to bond with others. These electrons are responsible for the chemical properties of the element. Since they are the ones involved in forming bonds, knowing the number of valence electrons helps predict an element's behavior in chemical reactions.

For instance, Lithium has one valence electron, making it highly reactive, often participating in chemical reactions by losing that single electron. Magnesium, with its two valence electrons, also tends to lose these electrons to achieve a stable electron configuration. Aluminum, with three valence electrons, can lose these electrons as well, but is also known for forming more complex compounds.

Periodic Table

The periodic table is a powerful tool for chemists and students. It organizes elements in a way that allows easy determination of key properties, such as valence electrons. Elements are arranged in rows called periods and columns called groups.

When you look at the periodic table, the group number for the main-group elements (columns 1-2 and 13-18) tells you the number of valence electrons. For example:

• Lithium (Li) is in Group 1, therefore it has 1 valence electron.
• Magnesium (Mg) is in Group 2, and thus has 2 valence electrons.
• Aluminum (Al) is positioned in Group 13, which gives it 3 valence electrons.

By understanding how the periodic table works, you can quickly find out how many valence electrons an atom has, helping you draw its Lewis symbol.

Chemical Symbols

Chemical symbols are shorthand notations representing chemical elements on the periodic table. These symbols, usually one or two letters, are based on either English or Latin names of the elements.

For example:

• The symbol for Lithium is Li.
• The symbol for Magnesium is Mg.
• The symbol for Aluminum is Al.

Chemical symbols not only help in writing chemical equations concisely but are also essential when drawing Lewis symbols. With Lewis symbols, these chemical symbols are adorned with dots to indicate valence electrons, providing a visual representation of an atom's potential to form bonds.

Step-by-Step Solution

Working through a step-by-step solution to draw Lewis symbols can significantly enhance understanding. Here's a recap of the steps involved in drawing Lewis symbols.

• **Step 1**: First, find the element on the periodic table to determine the number of valence electrons. This involves identifying the group number, as shown in the previous sections.
• **Step 2**: Next, use the chemical symbol of the element as a base. Then, place a number of dots equal to the valence electrons around the chemical symbol. Make sure to distribute the dots evenly to represent the valence electrons correctly.

By carefully following each step, drawing the Lewis symbols becomes a simple, straightforward process. This systematic approach helps reinforce understanding and application of the concepts involved.