Question

Draw Lewis symbols showing the valence electrons of the following atoms. (a) \(\mathrm{Kr}\) (c) \(\mathrm{F}\) (e) \(\mathrm{Ba}\) (b) \(\mathrm{Sb}\) (d) In (f) \(\mathrm{N}\)

Short answer

The Lewis Electron Dot Symbols are derived based on the group numbers of the elements, representing their valence electrons. Symbols for \( \mathrm{Kr} \), \( \mathrm{F} \), \( \mathrm{Ba} \), \( \mathrm{Sb} \), \( \mathrm{In} \), and \( \mathrm{N} \) are drawn with dots indicating 8, 7, 2, 5, 3, and 5 electrons respectively.

Step-by-step solution

Identify the Group Number

The first step is to determine the group number of each atom on the periodic table. The group number corresponds to the number of valence electrons. For example, Group 1 elements have 1 valence electron, Group 2 have 2 valence electrons, Groups 3-12 (the transition metals) vary, and Groups 13-18 correspond to 3 - 8 valence electrons.

Drawing the Lewis Electron Dot Symbols

In this step, the Lewis symbols for each atom are drawn with the chemical symbol and the corresponding valence electrons as dots. The dots represent valence electrons surrounding the chemical symbol, while attempting to pair the dots (up to 8) if possible.\n\n(a) \( \mathrm{Kr} \): Krypton (Group 18) has 8 valence electrons. Its Lewis symbol is \(\mathrm{Kr}\) with 8 dots around.\n(c) \( \mathrm{F} \): Fluorine (Group 17) has 7 valence electrons. Its Lewis symbol is \(\mathrm{F}\) with 7 dots around.\n(e) \( \mathrm{Ba} \): Barium (Group 2) has 2 valence electrons. Its Lewis symbol is \(\mathrm{Ba}\) with 2 dots around.\n(b) \( \mathrm{Sb} \): Antimony (Group 15) has 5 valence electrons. Its Lewis symbol is \(\mathrm{Sb}\) with 5 dots around.\n(d) \( \mathrm{In} \): Indium (Group 13) has 3 valence electrons. Its Lewis symbol is \(\mathrm{In}\) with 3 dots around.\n(f) \( \mathrm{N} \): Nitrogen (Group 15) has 5 valence electrons. Its Lewis symbol is \(\mathrm{N}\) with 5 dots around.

Key concepts

Valence Electrons

Valence electrons are the electrons found in the outermost shell of an atom. These electrons play a crucial role in chemical bonding and reactions. They determine how an atom interacts with other atoms, making them key to understanding reactivity.

• The number of valence electrons can be determined by the group number on the periodic table for elements in the main groups (excluding transition metals).
• Elements in Group 1 have one valence electron, while those in Group 18 have eight, making them chemically stable. This stability is seen in noble gases like krypton (Kr).
• Valence electrons are represented as dots in Lewis structures, aiding visualization of their role in compounds.

Knowing how to count and draw valence electrons is vital for mastering chemistry fundamentals.

Periodic Table Groups

Periodic table groups are vertical columns in the periodic table. These groups categorize elements with similar chemical properties, largely due to having the same number of valence electrons.

• The groups are numbered from 1 to 18, with each number largely indicating the number of valence electrons for main-group elements.
• The main-group elements include Groups 1-2 and 13-18, excluding the transition metals found in Groups 3-12.
• For example, Group 17 elements like fluorine (F) and Group 15 elements like nitrogen (N) share common properties within their groups due to their 7 and 5 valence electrons, respectively.
• This consistency allows for predictions about reactivity and the formation of compounds. Barium (Ba) from Group 2, for instance, typically forms bonds by losing its two valence electrons.

Understanding these groups helps predict the behavior and interactions of elements.

Drawing Lewis Structures

Lewis structures, or Lewis dot diagrams, are a simple way to represent the valence electrons of atoms. They help in understanding and predicting how atoms bond in molecules.

• To draw a Lewis structure, start with the element's symbol and surround it with dots representing its valence electrons.
• For example, krypton (Kr), with its 8 valence electrons, is drawn as the symbol "Kr" surrounded by 8 evenly spaced dots.
• It's important to understand how to pair and spread these dots around the atomic symbol, representing potential bonding sites.
• Practice by applying these rules to diverse elements like antimony (Sb) with 5 dots, or indium (In) with 3, to visualize their electron arrangements. These structures simplify visualizing molecular interactions and predicting chemical bonding patterns.

Mastering Lewis dot diagrams enhances comprehension of complex chemical processes.