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Ions and Oxidation. Octet Rule. Valence Electrons – Electrons in the outermost orbitals of the atom (Highest energy level ). Atoms become stable by having eight electrons in their outer most orbital. They lose or gain electrons to achieve this. Exception – Helium, only fills up to 1s 2.
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Octet Rule • Valence Electrons – Electrons in the outermost orbitals of the atom (Highest energy level). • Atoms become stable by having eight electrons in their outer most orbital. They lose or gain electrons to achieve this. • Exception – Helium, only fills up to 1s2
Ions • Ion – atom that has gained or lost electrons • Cation • atom that loses electrons • Loses valence electrons to look like noble gas on period above. • All Metals • Positive Oxidation # • Anion • Atom that gains electrons. • Gains valence electrons to look like noble gas on same period. • All Nonmetals (Excluding noble gases) • Negative Oxidation #
Oxidation Number • Oxidation number is the overall charge of the atom/ion. • Protons – electrons • Cations – lose electrons, end up with More protons than electrons. This gives a Positive (+) oxidation. • Anions – gain electrons, end up with More electrons than protons. This give a Negative (-) oxidation.
Extra Tidbits • Remember the atomic number = protons • Hydrogen can be both a cation (+1) or anion (-1). Can lose or gain a single electron.
Practice – do not write this all down, follow along!! • Look for Magnesium (Mg)on a Periodic Table • The noble gas on the period before is Neon. Magnesium (a metal) will lose electrons until it has same amount as Neon. • Neon has 10 electrons (same as # protons remember!) Magnesium has 12. So Magnesium will lose 2 electrons. • Magnesium will have a +2 oxidation.
More practice! • What will the oxidation # of Sodium be? • +1 • Aluminum? • +3 • What about Sulfur? • It’s a non-metal so will gain electrons! Wants to be like Argon. • -2 oxidation