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Ionic Bonds. How Ions Form. Ion – atom or group of atoms that has an electric charge Ionic bonds form when atoms gain or lose electrons. When an atom loses an electron, it becomes a positive ion. Ex. Li+ When an atom gains an electron, it becomes a negative ion. Ex. Cl -.
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How Ions Form • Ion – atom or group of atoms that has an electric charge • Ionic bonds form when atoms gain or lose electrons. • When an atom loses an electron, it becomes a positive ion. Ex. Li+ • When an atom gains an electron, it becomes a negative ion. Ex. Cl-
A compound that consists of ions is called an ionic compound. • The name of the positive ion comes first, followed by the name of the negative ion. (This means metal before nonmetal or metalloid, left before right)
Chemical Formulas • A chemical formula is a combination of symbols that shows the ratio of elements in a compound. Ex. CO = 1 carbon & 1 oxygen • A subscript tells you the ratio of elements in the compound. Ex. CO2 (2 = the subscript) • If there is no subscript (number), the number is understood to be 1.
Reminders • The magic number is 2 and 8. • All atoms will lose, gain, or share electrons to get to the magic number. • Ionic bonds generally occur between metals and nonmetals (or different sides of the periodic table). • Example: Cl has 7 electrons H has 1 electron HCl has 8 so the two combine