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Naming Common Compounds

Naming Common Compounds. Classifying Inorganic Compounds. There are three types of common inorganic compounds. They are   Ionic compounds   Molecular compounds   Acids. Ionic Compounds.

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Naming Common Compounds

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  1. Naming Common Compounds

  2. Classifying Inorganic Compounds There are three types of common inorganic compounds. They are •   Ionic compounds •   Molecular compounds •   Acids

  3. Ionic Compounds • Ionic compounds are composed of positively and negatively charged ions and are held together by electrostatic attractions called ionic bonds. • Ionic compounds do not contain molecules

  4. Identifying Ionic Compounds • Metals tend to form positive ions, and non-metals tend to form negative ions. • Hydrogen, H+1, and ammonium ion, NH4+1, are the only common positive ions that do not contain a metal. • Of these two, ammonium is found in ionic compounds, and hydrogen is found in acids. • To identify a compound as being ionic, scan the name or the formula and identify the elements. • If the compound contains a metal (or the ammonium ion) and at least one non-metal, it is almost always an ionic compound.

  5. Naming Ionic Compounds • Ionic compound names have two parts: the cation (positive ion) name and the anion (negative ion) name. • The positive ion is written first. Example: K2S is potassium sulfide. Potassium is the name of the cation; sulfide is the name of the anion. • Cations have the same name as their element, though they may also have a number. Example: Mg+2 is the magnesium ion; Fe+3 is the iron (III) ion. • Anions with only one atom have the same root name as their element but end with the suffix     “-ide.” Example: Cl-1 is the chloride ion. • You will need to learn the names of the monatomic (single atom) ions and their charges. This is a periodic property. • Many metals can form more than one cation. These metals can be found in the transition and lower p-block parts of the periodic table. • The names of these ions have Roman Numerals in parenthesis after the metal name. This number is the charge of the ion. Example: FeCl3 is iron (III) chloride, because the iron ion in this compound has a +3 charge. FeCl2 is iron (II) chloride, because the iron ion has a +2 charge.

  6. Ionic Compounds having Polyatomic Ions • Many ionic compounds have polyatomic (many atom) ions. • To name these, name the cation then the anion. Example: NH4OH is ammonium hydroxide. • In order to name ionic compounds (and acids) you will need to memorize the names of the common polyatomic ions.

  7. Formulas of Ionic Compounds • If given the name, identify the formulas of each of the ions then use subscripts to make the charges neutral. Examples: • Magnesium bromide contains the ions Mg+2 and Br -1, so the formula is MgBr2. • Tin (IV) sulfate contains the ions Sn+4 and SO4-2, so the formula is Sn(SO4)2.

  8. Acids • Acids are substances that react with water to form an aqueous hydrogen ion, H+1(aq). • These compounds have characteristics in common with both ionic and molecular compounds • Identifying Acids • There are different systems for classifying acids. Some acids have names that fit the following rules. Others have names that fit the ionic or binary molecular compound naming rules. • To determine if a compound is an acid for naming purposes, scan the chemical formula. The formula for an acid begins with H.

  9. Naming Acids • Scan the formula. Identify the anion. Acid names use the name of the anion as a root word for the acid name. Example: HF is hydrofluoric acid. It has a root word “fluor-” from the name of the fluoride ion. • If the name of the anion ends with the suffix “-ate” the acid name will have the format “___ic acid.” Example: H2SO4 is sulfur icacid because SO4-2 is the sulfate ion. • If the name of the anion ends in with the suffix “_ite” the acid name will have the format “___ous acid.” Example: HNO2 is nitrousacid because NO2-1 is the nitrite ion. • If the name of the anion ends with the suffix “-ide” the acid name will have the format “hydro___icacid.” Example: HCN is hydrocyanicacid because CN-1 is the cyanideion.

  10. Molecular Compounds • Molecular compounds are composed of molecules in which atoms share electrons via bonds. • Identifying Molecular Compounds • Molecular compounds contain two or more non-metals but not the ammonium ion, NH4+1. • To determine if a compound is molecular scan the formula for a metal or the ammonium ion—these will be written at the beginning of the formula. If the compound does not contain a metal, it is probably molecular. • Compound that have formulas beginning with H and anion with names ending in “-ide” can be named as acids or molecular compounds. • If the compound is in aqueous solution, name it as an acid. Example: HF(aq) is hydrofluoric acid. • If the compound is a gas, name it as a molecular compound. Example: H2S(g) is hydrogen sulfide. • Organic compounds contain carbon. Some organic compounds follow the general rules for binary molecular compounds (carbon dioxide, carbon monoxide, carbon tetrachloride) but most follow a special naming system.

  11. Molecular Compounds Binary Molecular Compounds • Binary molecular compounds contain two non-metals. • Some have common names from antiquity. Common names you will need to know: ammonia, NH3, and water, H2O.   Naming Binary Molecular Compounds • The first element in the formula is the first element in the name. Example: CO2 is carbon dioxide; the same order in the name as in the formula. • Use prefixes to indicate the number of atoms of each of the elements in the molecule. Example: CO2 is carbon dioxide; di- prefix for two oxygen atoms.

  12. Molecular Compounds • The two elements in the compound are named as two separate words. Each word will have its own prefix. The prefix “mono-” is not used for the first element. Example: CO2 is carbon dioxide NOT monocarbon dioxide. • End the name with the suffix “-ide.” Example: CO2 is carbon dioxide; the name ends with  “-ide.” • More Examples • SF6 is sulfur hexafluoride. • N2O5 is dinitrogen pentoxide. • Cl2O is dichlorine monoxide. • Note that an extra vowel was dropped in the names of the last two. This makes the names easier to pronounce.

  13. Formulas of Binary Molecular Compounds To write the formula from the name of a binary molecular compound, scan the name and identify the two non-metallic elements. Write the symbol for the first element first and the second element second. Use the numbers from the prefixes as subscripts. Example: Tetraphosphorus decasulfide has P and S as the elements in its formula. P will appear first in the formula. The subscript on P is 4. The subscript on S is 10. The formula is P4S10.

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