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Learn about electron configurations and how electrons are arranged around the nucleus. Discover the concept of valence electrons and their role in bonding between atoms. Explore the periodic table to understand electron distribution.
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Electron Configurations • Electrons are key players in chemical bonding. To predict how atoms will bond, we use a configuration. These show how the electrons are arranged around the nucleus • Electrons are arranged in shells, levels or orbitals • How do we know how many electrons an atom has? • Different levels can hold different numbers of electrons: level 1-can hold 2 electrons level 2-can hold 8 electrons level 3-can hold 18 electrons • Note: There are more levels or obitals-formula to determine the amount of electrons in each level is 2n2
Valence Electrons • The electrons on the outer shell/level are called valence electrons. • Bonding between atoms occurs between valence electrons in atoms. • An atom with a full outer shell will be stable-will not bond with other atoms. Example: Argon-has 8 valence electrons Example: Neon-has 8 valence electrons
Practice: Draw an electron configuration and indicate the number of valence electrons. • Boron • Lithium • Nitrogen • Aluminum • Calcium
Groups on the Periodic Table • Group 1-has 1 valence electron • Group 2-has 2 valence electrons • Groups 3-12-have 2 or more valence electrons • Group 13-has 3 valence electrons • Group 14-has 4 valence electrons • Group 15-has 5 valence electrons • Group 16-has 6 valence electrons • Group 17-has 7 valence electrons • Group 18-has 8 valence electrons (except Helium)
When you take high school chemistry, you will learn more about the orbitals and how electrons are distributed around the nucleus. You will also learn how to write the configurations: 1s2, 2s2, 2p6, 3s2, 3p6, 3d 10
The periodic table is also organized to show electron distribution