Nomenclature Ionic Compounds

Learning Goals We are learning to – Name ionic compounds – Understand the charges of ions in ionic compounds – Use what we know about ionic charge to determine chemical formulas – Name ionic compounds containing polyatomic ions

Ionic Compounds Recall: An ionic compound is formed from one or more positively charged ions and one or more negatively charged ions In ionic bonding, electrons are transferred from one atom to another. The oppositely charged ions are attracted to each other by electrostatic forces, which are the basis of the ionic bond.

Ionic Bonding Metals lose electrons, become positively charged – sodium, potassium, magnesium, calcium Non-metals gain electrons, become negatively charged – chlorine, silicon, oxygen, sulphur The result of bonding is a compound that has an overall neutral charge

Drawing Chemical Symbols When a sodium atom loses one electron and becomes a positively charged ion it is symbolized as: Na + to indicate a charge of +1 – When more than one electron is exchanged the number is placed before the charge. – sulfur gains 2 electrons is symbolized as S 2- What about the following elements? – chlorine gains 1 electron – calcium loses 2 electrons – oxygen gains 2 electrons – aluminum loses 3 electrons

Ionic Formula The formula of an ionic compound is derived by combining ions such that a neutral compound is created Let’s try some examples: – calcium and chlorine – magnesium and oxygen – lithium and bromine – magnesium and nitrogen

Naming Ionic Compounds 1.Name the metal ion first – same as element name In KBr the name of the K + ion is potassium. 2.Name the non-metal ion second. When non-metal becomes a negative ion, the ending of its name changes to “ide” A bromine atom gains an electron to become a bromide ion 3.Combine the names The name of KBr is potassium bromide

Naming Ionic Compounds Let’s try some examples: – calcium and chlorine – magnesium and oxygen – lithium and bromine – magnesium and nitrogen

Naming Ionic Compounds Some metals are able to form more than one kind of ion – EXAMPLES: copper, lead, iron, nickel Roman numerals are used to indicate ionic charge – EXAMPLE: There are two types of copper ions: Cu + and Cu 2+ Copper(I) chloride: Cu + forms the compound (CuCl) Copper(II) chloride: Cu 2+ forms the compound (CuCl 2 )

Naming Ionic Compounds You can determine the Roman Numeral to use in the name of a multivalent ion from the subscripts in the compounds formula. – EXAMPLE: CrCl 3 – Chlorine holds a charge of -1 and there are 3 of them in the chemical formula, therefore to make the molecule neutral the chromium must have a charge of +3. – Name is chromium(III) chloride

Naming Ionic Compounds Let’s try some examples: – FeCl 2 – FeCl 3 – CuN 2 – Ni 2 O 3

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