lecture3sf - Ions Ions are charged particles. Ordinary...

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Ions Ions are charged particles. Ordinary atoms are uncharged (neutral); they have an equal number of protons and electrons. An atom may become an ion by losing or gaining electrons. Positive ions (cations) are formed when an atom loses electrons. Negative ions (anions) are formed when an atom gains electrons. Na+ is an ion of sodium. It contains 11 protons and 10 electrons. Cl- is an ion of chlorine. It contains 17 protons and 18 electrons. Ionic Compounds These are composed of + and - ions. The overall charge on the compound is zero. Binary ionic compounds These have only two elements, and consist of simple monoatomic positive and negative ions. Some common monatomic ions: All group 1A metals form 1+ ions All group 2A metals form 2+ ions Group 3A metals, most commonly aluminum, form 3+ ions All group 7A halogens form 1- ions All group 6A elements form 2- ions Group 5A elements, most commonly nitrogen, phosphorus form 3- ions In naming compounds, the positive ion comes first, followed by the negative ion. Negative monoatomic ions always have an “ide” suffix. Examples: Sodium chloride NaCl Magnesium chloride MgC 2 Aluminum chloride AlCl 3 Sodium oxide Na 2 O Magnesium oxide MgO Aluminum oxide Al 2 O 3 Sodium nitride Na 3 N Magnesium nitride Mg 3 N 2
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several possible ionic charges. In such a case, a Roman numeral designates the charge of the positive ion. Iron (II) chloride FeCl 2 Iron (III) chloride FeCl 3 Copper (I) oxide Cu 2 O Copper (II) oxide CuO Students should know silver ion, Ag + and zinc ion, Zn 2+ . These ions always have these charges and no Roman numeral is used. Polyatomic Ions Many negative ions are polyatomic. Most common polyatomic ions contain 3 or four oxygen atoms + the element that’s part of their name. Some nomenclature guidelines: Suffix Ion “ate” contains 3 or 4 oxygens + the element that’s in the name “ite” contains one less oxygen than the corresponding “ate” ion but with the same charge bi___ate add one hydrogen atom to the corresponding “ate” ion and or increase the charge by 1. hydrogen ___ ate bi___ite add one hydrogen atom to the corresponding “ite” ion and or increase the charge by 1. hydrogen ___ite
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lecture3sf - Ions Ions are charged particles. Ordinary...

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