NAMING COMPOUNDS AND WRITING FORMULAS CH 6 3

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NAMING COMPOUNDS AND WRITING FORMULAS CH 6. 3 SC. 912. N. 3. 5 SC.

NAMING COMPOUNDS AND WRITING FORMULAS CH 6. 3 SC. 912. N. 3. 5 SC. 912. P. 8. 7

LEARNI NG GOALS What information do the name and formula of an ionic compound

LEARNI NG GOALS What information do the name and formula of an ionic compound provide? What information do the name and formula of a molecular compound provide?

DESCRIBIN G IONIC COMPOUN DS • The name of an ionic compound must distinguish

DESCRIBIN G IONIC COMPOUN DS • The name of an ionic compound must distinguish the compound from other ionic compounds containing the same elements. • Example would be distinguishing between red copper oxide and black copper oxide. • The formula of an ionic compound describes the ratio of the ions in the compound.

BINARY IONIC COMPOUNDS • A compound made from only two elements is a binary

BINARY IONIC COMPOUNDS • A compound made from only two elements is a binary compound. • Naming binary ionic compounds is easy: the name of the cation is first, followed by the name of the anion. • Example: Sodium (cation) Chloride (anion)

COMMON ANIONS • The name of an anion is formed by adding the suffix

COMMON ANIONS • The name of an anion is formed by adding the suffix –ide to the stem of the name of the nonmetal.

METALS WITH MULTIPLE IONS

METALS WITH MULTIPLE IONS

POLYATOMIC IONS • Covalently bonded group of atoms that has a positive or negative

POLYATOMIC IONS • Covalently bonded group of atoms that has a positive or negative charge and acts as a unit is a polyatomic ion.

WRITING FORMULAS FOR IONIC COMPOUNDS • The symbol of the cation is first, followed

WRITING FORMULAS FOR IONIC COMPOUNDS • The symbol of the cation is first, followed by the symbol of the anion. • Use subscripts to show the ratio of the ions in the compound. • Parentheses are used with the subscript for polyatomic ions. The formula for iron (III)

WRITING FORMULAS FOR IONIC COMPOUNDS • Because all compounds are neutral, the total charges

WRITING FORMULAS FOR IONIC COMPOUNDS • Because all compounds are neutral, the total charges on the cations and anions must add up to zero. • The formula for sodium sulfide is Na 2 S. There must be two sodium ions for each sulfide ion. • The 2 - charge on one sulfide ion is balanced by

WRITING FORMULA PRACTICE Write the formula for the following compounds. 1. Calcium chloride Ca.

WRITING FORMULA PRACTICE Write the formula for the following compounds. 1. Calcium chloride Ca. Cl 2 Ca with a charge of 2+ and Cl with a charge of 1– 2. Calcium Oxide Ca. O Ca with a charge of 2+ and oxide with 2 -

DESCRIBING MOLECULAR COMPOUNDS • The name and formula of a molecular compound describe the

DESCRIBING MOLECULAR COMPOUNDS • The name and formula of a molecular compound describe the type and number of atoms in a molecule of the compound. • General rule is that most metallic elements appear first in the name. • The second element is changed to and in the suffix -ide, as in carbon dioxide.

DESCRIBING MOLECULAR COMPOUNDS • There may be more than one molecular compound that can

DESCRIBING MOLECULAR COMPOUNDS • There may be more than one molecular compound that can exist with the same two elements. • The Greek prefixes in the table are used to name molecular compounds. • The prefix octa - means “eight”

DESCRIBING MOLECULAR COMPOUNDS • Two compounds that contain nitrogen and oxygen have the formulas

DESCRIBING MOLECULAR COMPOUNDS • Two compounds that contain nitrogen and oxygen have the formulas N 2 O 4 and NO 2. • The name of the compound with the formula N 2 O 4 is dinitrogen tetraoxide. • The name for the compound with the formula NO 2 is mononitrogen dioxide. The prefix mono- often is not used for the first element in the name, so a more common name is nitrogen dioxide.

WRITING MOLECULAR FORMULAS To write the formula for a molecular compound, write the symbols

WRITING MOLECULAR FORMULAS To write the formula for a molecular compound, write the symbols for the elements in the order the elements appear in the name. • The prefixes indicate the number of atoms of each element in the molecule. • The prefixes appear as subscripts in the formulas. • If there is no prefix for an element in the name, there is only one atom of that element in the molecule.

WRITING MOLECULAR FORMULAS PRACTICE 1. Diphosphorous tetrafluoride • Phosphorus has the symbol P. Fluorine

WRITING MOLECULAR FORMULAS PRACTICE 1. Diphosphorous tetrafluoride • Phosphorus has the symbol P. Fluorine has the symbol F. • Di- indicates two phosphorus atoms, and tetraindicates four fluorine atoms. • The formula for the compound is P 2 F 4.