Ch 6 & 7 Ionic Bonding and Nomenclature Student Guided Notes Introduction to Chemical Bonding Atoms seldom exist as particles in nature. Oxygen you breathe and water you drink are combinations of that are held together by chemical bonds. Chemical Bond a mutual attraction between the and electrons of different atoms that binds the atoms together. Chemicals are bonded together because as individual particles they are at relatively potential. Nature wants potential energy. Ionic Bonding When atoms bond, their valence electrons (electrons in the s & p orbitals of the HIGHEST energy level) are redistributed in ways that make the atom stable. bonding chemical bonding that results from the electrical attraction between cations ( ions) and anions ( ions). In a purely Ionic Bond atoms give up electrons to other atoms. Examples: salts such as NaCl, LiCl, MgBr2, and compounds with polyatomic ions CaCO3 Characteristics of Ionic Bonds and Compounds The bonds between atoms in a compound determine many of the compounds properties. Most ionic compounds exist as crystalline. A crystalline solid is a crystal of any ionic compound that is a three-dimensional of positive and negative ions mutually attracted to each other. Where the Crystalline Solid Forms a crystal an orderly arrangement of ions into an ionic crystal. lattice energy -energy released when 1 mole of ionic crystal compound is formed from gaseous atoms. High points due to strong attractive forces. Much energy is required to break bonds. Properties of Ionic Compounds In molten or liquid state, ionic compounds are good conductors of electricity ions move freely to carry current. An an ionic compound in an solution (ions are free to move). Ionic Compounds are good electrical conductors in the state, because the ions cannot move. These compounds are hard but any slight shift in row of ions causes repulsive forces to build up and make the layers completely.
Energy and Ionic Bonds Endothermic energy is during a reaction. Exothermic energy is during a reaction. The formation of ionic compounds is almost always. If the energy that was in the reaction forming the compound is back into the compound the holding the ions together will. Lattice the energy required to one mole of the ions in an ionic compound the more the lattice energy, the the force of attraction. This is directly related to the of the ions bonded. Smaller generally have a more value (nucleus closer to valence e - ). Higher the oxidation of the ions the more negative the value. Ionic Compounds Most of the rocks and that make up Earth s crust consist of positive and negative ions held together by ionic bonding. Example: table salt, NaCl, consists of sodium and chloride ions combined in a one-to-one ratio Na + Cl so that each positive charge is by a negative charge. An ionic compound is composed of positive and negative ions that are so that the numbers of positive and negative charges are. Ionic Bonding and Ionic Compounds Formation of Ionic Compounds Na Sodium atom Cl Chlorine atom The sodium atom has valence electron and the chlorine atom has valence electrons. Atoms of sodium and other alkali metals easily one electron to form cations. Atoms of chlorine and other halogens easily gain one electron to form anions. Na Sodium atom + Cl Na + Chlorine atom Sodium cation - + Cl Chloride anion Transition Metals can form than one type of ion. metals form both 2+ (most common) and 3+ ions or more (if d electrons are lost) Pseudo-noble gas config. group 1B ~ 4A in periods 4-6 lose e - s to form full s, p, d sublevels Zn ~ 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 Zn loses the electrons to form a stable 2+ ion leaving 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10
Names & Formulas for Ionic Compounds Formula unit represents the simplest of the ions represented in an ionic compound The number of electrons gained by the nonmetal must the number lost by the metal atoms, so the overall charge of the compound formed is. Determining charge composed of metal (+) and nonmetal (-) ions. Monatomic ions are a one ion (Na +, Cl -, Mg 2+ ). number will give information. Oxidation number (state) - equals the number of electrons transferred and is used to determine the for the ionic compound. Overall the number of a compound must equal zero. Chemical formula: Cation is always written, followed by the Anion. Subscripts are given if than one atom is required. If only one atom needed then no subscript is required (assumed). Practice: Goal: Charge on the compound to equal zero. 1. potassium + iodide 2. magnesium + chloride 3. aluminum + bromide 4. cesium + nitride 5. barium + sulfide Polyatomic ions Polyatomic ions are ions made up of than one atom. The given applies to the entire group of atoms. The ion acts as an ion. The same rules for writing the formula applies. If more than one polyatomic ion is required, use ( ) then subscript. Practice 1. sodium nitrate 2. calcium chlorate 3. aluminum carbonate 4. potassium chromate 5. magnesium carbonate Naming Ions and Ionic Compounds
Nomenclature a systematic method of chemical compounds. a) a polyatomic ion composed of an element, usually a nonmetal, bonded with oxygen. Many are the same nonmetal with different numbers of oxygen atoms. The ion with oxygen atoms is named using the root of the nonmetal + the suffix. The ion with oxygen atoms is named using the root of the nonmetal + the suffix. Examples: (NO3 - nitrate, NO2 - nitrite, SO4 2- sulfate, SO4 2- sulfite) Chlorine has 4 oxyanions: perchlorate ClO4 - (has the most O) Chlorate ClO3 - Chlorite ClO2 - Hypochlorite ClO - (has the fewest O) Rules for ionic nomenclature: 1. Write the name of the cation 1 st using the name 2. Write the name of the anion 2 nd using the word of the element + Example: NaBr Sodium Bromide CaCl2 calcium chloride Transition metals and metals beyond groups 1 & 2 can have more than one oxidation #. Write the elemental name then give oxidation number as Roman numeral in parentheses. ( ) Examples: Fe2O3 iron(iii) oxide, FeO iron(ii) oxide If a polyatomic ion, use its name Examples: KOH potassium hydroxide Cu(NO3)2 copper(ii) nitrate Hydrates Ag2CrO4 silver chromate What is a hydrate? A hydrate is an compound that has water inside the structure of the compound. This water is trapped not chemically bonded. Terms that relate to hydrates: Anhydrate: A HYDRATE THAT HAS HAD WATER REMOVED. Dehydration: THE PROCESS OF REMOVING WATER USING. Rules for Naming Hydrated Ionic Compounds
Hydrides form when Hydrogen bonds with a Group or Group metal. ionic compounds (i.e., hydrates) have a specific number of molecules in their chemical formulas. In the, these water molecules are part of the structure of the compound. Rule 1. The ionic compound is named first by using the rules for naming ionic compounds (e.g., Ba(OH)2 8H2O = " "). Rule 2. are attached to the word "hydrate" to indicate the number of molecules per formula unit for the compound (e.g., Ba(OH)2 8H2O; 8 water molecules = " hydrate"). Rule 3. When the chemical formula for a hydrated ionic compound is written, the formula for the ionic compound is separated from the waters of hydration by a centered " ". Ba(OH)2 8H2O Prefixes for Nomenclature Number of Atoms Prefix 1 Mono 2 Di 3 Tri 4 Tetra 5 Penta 6 Hexa 7 Hepta 8 Octa 9 Nona 10 Deca Practice What is the correct name for the following compounds? 1. FeF2 4H2O? 2. Ba(OH)2 8H2O? 3. tin(ii) chloride dihydrate? 4. copper(ii) acetate monohydrate?