Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)

Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook

Bruice 8th Edition

Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)

Problem 5b

Chapter 1, Problem 5b

How many valence electrons do chlorine, bromine, and iodine have?

Verified step by step guidance

Determine the group number of chlorine, bromine, and iodine in the periodic table. These elements belong to Group 17 (also known as the halogens).

Recall that the group number for main group elements corresponds to the number of valence electrons. Since chlorine, bromine, and iodine are in Group 17, they each have 7 valence electrons.

Understand that valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding.

Verify this by writing the electron configuration for each element: Chlorine (Cl): [Ne]3s²3p⁵, Bromine (Br): [Ar]4s²3d¹⁰4p⁵, Iodine (I): [Kr]5s²4d¹⁰5p⁵. In each case, the outermost s and p orbitals contain 7 electrons.

Conclude that chlorine, bromine, and iodine each have 7 valence electrons, consistent with their position in Group 17 of the periodic table.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial for determining how an element interacts with others. They play a key role in chemical bonding, as they are involved in the formation of bonds with other atoms. The number of valence electrons can often be predicted based on an element's position in the periodic table.

Group 17 Elements

Chlorine, bromine, and iodine belong to Group 17 of the periodic table, also known as the halogens. Elements in this group typically have seven valence electrons, which makes them highly reactive, as they seek to gain one additional electron to achieve a stable octet configuration. Understanding their group characteristics helps in predicting their chemical behavior.

Periodic Table Trends

The periodic table exhibits trends in the number of valence electrons across different groups. As you move from left to right across a period, the number of valence electrons increases. For halogens, this trend is consistent, as they all have seven valence electrons, which is essential for understanding their reactivity and bonding patterns.

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Related Practice

Textbook Question

Write the ground-state electronic configuration for chlorine (atomic number 17), bromine (atomic number 35), and iodine (atomic number 53).

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Textbook Question

Look at the relative positions of each pair of atoms listed here in the periodic table. How many core electrons does each have? How many valence electrons does each have?

c. nitrogen and phosphorus

d. magnesium and calcium

Textbook Question

How many valence electrons do the following atoms have?

a. boron

b. nitrogen

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Textbook Question

Chlorine has two isotopes, ³⁵Cl and ³⁷Cl; 75.77% of chlorine is ³⁵Cl, and 24.23% is ³⁷Cl. The atomic mass of ³⁵Cl is 34.969 amu, and the atomic mass of ³⁷Cl is 36.966 amu. What is the atomic mass of chlorine?

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Textbook Question

Look at the relative positions of each pair of atoms listed here in the periodic table. How many core electrons does each have? How many valence electrons does each have?

a. carbon and silicon

b. oxygen and sulfur

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Textbook Question

a. Find potassium (K) in the periodic table and predict how many valence electrons it has.

b. What orbital does the unpaired electron occupy?

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