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

Verified step by step guidance

1. Determine the group number of chlorine, bromine, and iodine in the periodic table. These elements belong to Group 17 (also known as the halogens).
2. 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.
3. Understand that valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding.
4. 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.
5. Conclude that chlorine, bromine, and iodine each have 7 valence electrons, consistent with their position in Group 17 of the periodic table.

Key Concepts

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.