1. Naming Ionic and Molecular Compounds

2. Naming Compounds Helps get rid of the confusion that can result from inaccurately naming compounds Helps get rid of the confusion that can result from inaccurately naming compounds Example: black board chalk and the chalk in TUMSExample: black board chalk and the chalk in TUMS Naming compounds also shows the importance of using names that provide information about the chemical composition of a substance Naming compounds also shows the importance of using names that provide information about the chemical composition of a substance The International Union of Pure and Applied Chemistry (IUPAC) is the body responsible for naming compounds. The International Union of Pure and Applied Chemistry (IUPAC) is the body responsible for naming compounds.

3. Ionic Compounds Form when electrons transfer from one atom to another. Form when electrons transfer from one atom to another. Example: Sodium Chloride (NaCl) “ table salt ”Example: Sodium Chloride (NaCl) “ table salt ” Positively charged sodium ions are attracted to negatively charged chloride ions. Positively charged sodium ions are attracted to negatively charged chloride ions. The two kinds of ions group together in an organized array called a crystal lattice. The two kinds of ions group together in an organized array called a crystal lattice. The lattice is made up of one such sodium ion for every one chloride ion The lattice is made up of one such sodium ion for every one chloride ion Such a neutral unit is called a formula unit Such a neutral unit is called a formula unit

4. Ionic Compounds

5. Recall that an atom of sodium has 1 valence electron and a chlorine atom has 7 valence electrons Recall that an atom of sodium has 1 valence electron and a chlorine atom has 7 valence electrons When the two combine the sodium atom transfers one electron to the chloride atom When the two combine the sodium atom transfers one electron to the chloride atom As a result, both atoms now have full other energy levels (they are stable)As a result, both atoms now have full other energy levels (they are stable) This type of bonding (the transfer of electrons) is called ionic bondingThis type of bonding (the transfer of electrons) is called ionic bonding Ionic bonds form between metals and non-metalsIonic bonds form between metals and non-metals

6. Ionic Compounds

7. Ionic Bonding

8. Ionic Compounds Common properties of Ionic Compounds Common properties of Ionic Compounds Solid at room temperatureSolid at room temperature Dissolve in waterDissolve in water Solutions if ionic compounds conduct electricitySolutions if ionic compounds conduct electricity

9. Ionic Compounds There are thousands of Ionic Compounds There are thousands of Ionic Compounds Several have common names Several have common names They also have chemical names They also have chemical names See table A2.2 on page 41See table A2.2 on page 41 The state of an element or compounds is indicated by a subscript: (s) for solid, (l) for liquid, (g) for gas and (aq) for aqueous The state of an element or compounds is indicated by a subscript: (s) for solid, (l) for liquid, (g) for gas and (aq) for aqueous Aqueous is a compound or element dissolved in waterAqueous is a compound or element dissolved in water

10. Naming Ionic Compounds All names of ionic compounds have 2 parts All names of ionic compounds have 2 parts Every ionic compound is made up of a cation and an anionEvery ionic compound is made up of a cation and an anion The naming Rules work like this: The naming Rules work like this: 1.Name the cation first by using the element ’ s name. (it is usually a metal ion) 2.Name the anion second by using the first part of the element ’ s name and changing the last part to “ -ide ” (it is usually a non-metal ion)

11. Naming Ionic Compounds - Example FormulaCationAnionName NaCl (s) Na + Cl - Sodium Chloride BaF 2(s) Ba 2 + F-F-F-F- Barium fluoride K 3 N (s) K + N 3- Potassium Nitride

12. Formulas for Ionic Compounds Contain element symbols that identify each type of ion present Contain element symbols that identify each type of ion present In some formulas, the symbols are followed by subscript numbers that indicated the ratio of ions in the compound In some formulas, the symbols are followed by subscript numbers that indicated the ratio of ions in the compound For example in BaF 2(s) there is one barium ion for every two fluoride ionsFor example in BaF 2(s) there is one barium ion for every two fluoride ions This represents the formula unit (the smallest amount of the substance with the composition shown by the chemical formula)This represents the formula unit (the smallest amount of the substance with the composition shown by the chemical formula)

13. Formulas for Ionic Compounds All ionic compounds are composed of an equal number of positive and negative charges. Cations = Anions All ionic compounds are composed of an equal number of positive and negative charges. Cations = Anions Example: NaCl Example: NaCl Na + and Cl -, both charges cancel one another out and therefore there is an equal number of positive and negative chargesNa + and Cl -, both charges cancel one another out and therefore there is an equal number of positive and negative charges

14. Formulas for Ionic Compounds All ionic compounds are composed of an equal number of positive and negative charges. Cations = Anions All ionic compounds are composed of an equal number of positive and negative charges. Cations = Anions Example: AlCl 3 Example: AlCl 3 Each aluminium atom loses 3 electrons and each chloride atom gains 1Each aluminium atom loses 3 electrons and each chloride atom gains 1 The aluminium ion has a charge of 3+ and the chloride ion has a charge of 1-The aluminium ion has a charge of 3+ and the chloride ion has a charge of 1- Therefore, every one aluminium ion combines with three chloride ionsTherefore, every one aluminium ion combines with three chloride ions The ration is one cation (Al 3+ ) to three anions (Cl - ) and thus the formula, AlCl 3The ration is one cation (Al 3+ ) to three anions (Cl - ) and thus the formula, AlCl 3 See next slide with tableSee next slide with table

15. Formulas for Ionic Compounds StepsExamples Sodium chloride Aluminium chloride 1. Identify the ions and their charges Sodium: Na + Chloride: Cl - Aluminium: Al 3+ Chloride: Cl - 2.Determine the total charges needed to balance Na + :1 Cl - :1 Al 3+ :3 Cl - :1+1+1=3 3. Note the ratio of cations to anions 1 to 1 1 to 3 4.Use subscripts to write the formula, if needed NaCl AlCl 3

16. The Method of Lowest Common Multiple Another way of determining the correct formula for an ionic compound Another way of determining the correct formula for an ionic compound 1 st, find the lowest common multiple of the charges for the 2 ions1 st, find the lowest common multiple of the charges for the 2 ions 2 nd, divided by the combining capacity of one ion to get the correct subscript for that ion2 nd, divided by the combining capacity of one ion to get the correct subscript for that ion Example on board (copy)Example on board (copy)