+ NOMENCLATURE Sarah Fleck Chemistry

+ Learning Objectives Distinguish between ionic and molecular compounds Define cation and anion and relate them to metal and nonmetal Key Terms Molecule Molecular Compound Ion Cation Anion Ionic Compound

+ Background About 100 different elements make up millions of different compounds Communication is key Scientists must have a common language Naming is an essential skill in chemistry

+ Molecules & Molecular Compounds Monatomic – consist of a single atom Only noble gases tend to exist as isolated atoms Molecule – two or more atoms that act as a unit Diatomic – Oxygen (O 2 ) Triatomic – Ozone (O 3 ) Molecular Compounds – Compounds composed of molecules Low melting & Boiling points (Gas or liquid at room temp) Atoms of 2 or more non-metals

+ Ions NOT ALL COMPOUNDS ARE MOLECULAR! Ions – atoms or groups of atoms that have a positive or negative charge. Forms when an atom or group of atoms loses or gains electrons. Na – 11 p+ and 11 e - = net charge of 0 When forming a compound Na tends to lose 1 of its electrons p + will not equal e - any longer, Na becomes a positive ion

+ Cations & Anions Cation – atom or group of atoms with a positive charge Loses 1 or more electrons Anion – atom or group of atoms with a negative charge Gains 1 or more electrons Symbol for an ion – number with a charge after Sodium cation – 11 protons & 10 electrons = Na + Magnesium cation – l2 protons & 10 electrons = Mg 2+ Chloride Anion – 17 protons & 18 electrons = Cl -

+ Naming Cations

+ Naming Anions

+ Ionic Compounds Ionic compounds are composed of cations and anions and are electrically neutral Ionic compounds are usually solid crystals at room temperature and they melt at high temperatures More specifically they are composed of … METAL cations and NON-METAL anions Examples Sodium Chloride – table salt Calcium Oxide – lime

+ Molecular vs Ionic Compounds Characteristics of Molecular and Ionic Compounds CharacteristicMolecular CompoundIonic Compound Representative UnitMoleculeFormula Unit (balance of oppositely charged ions) Type of ElementsNonmetallicMetallic combined with non-metallic Physical StateSolid, Liquid, or GasSolid Melting PointLow (usually below 300 °C)High (usually above 300 °C)

+ Determining Charges of Ions In order to write chemical formulas you must be able to determine the types of ions that atoms tend to form. That means you must know the ionic charges obtained by the elements. Monatomic Ions – ions consisting of 1 atom Charges can be determined by the periodic table!

+ Ionic Charges Metallic Element – Same charge as the group number Non-metal Element – Charge is determined by subtracting the group number from 8

+ Ionic Charges Continued Groups 4B and 0 do not usually form ions Carbon & Silicon are found in molecular compounds Transition metals have more than one common ionic charge. (Tin and Lead as well, 2 metals in group 4B) Ex: Iron forms two metal cations; Fe 2+ and Fe 3+ Naming transition metal cations Stock system – roman numeral to indicate the charge

+ Name that charge! A. Sulfur (S) B. Lead (Pb), 4 electrons lost C. Strontium (Sr) D. Argon (Ar) E. Bromine (Br) F. Copper (Cu), 1 electron lost

+ Polyatomic Ions -ite-ate SO 3 2-, SulfiteSO 4 2-, Sulfate NO 2 -, NitriteNO 3 -, Nitrate ClO 2 -, ChloriteClO 3 -, Chlorate What pattern do you see in the naming of the polyatomic atoms to the below?

+ Common Polyatomic Ions

+ WRITING formulas for Binary Ionic Compounds Binary compounds are composed of two elements Crisscross method Charges are balanced = net charge of 0 Cation is written first For Example: Calcium Bromide CaBr 2 Ca 2+ + Br -

+ Practice – Write the formula for these binary compounds Copper (III) Sulfide Potassium Nitride

+ NAMING Binary Ionic Compounds What would you call CuO? Copper can have one of two charges; Cu + or Cu 2+ The charge of the transition metal is found by working backwards. How about SnO 2 ?

+ Practice Naming Binary Ionic Compounds CoI 2 Cs 2 O

+ Ternary Ionic Compounds Ternary Ionic Compounds – a compound that contains atoms of three different elements CaCO 3 Usually contain a polyatomic atomic ion How would you write the formula for calcium nitrate? Procedure is the same as that for binary ionic compounds Write the formula for each ion then balance the charges

+ Ternary Ionic Compound Example Calcium Nitrate Ca 2+ and NO 3 - Ca(NO 3 ) 2 Strontium Sulfate Sr 2+ and SO 4 2+ SrSO 4 Parenthesis are only needed when representing more than one polyatomic ion at a time

+ Try these ternary ionic compounds Potassium sulfate Magnesium hydroxide

+ Extra Information When you see bi- as a prefix it means there is H + as part of the ion. Bicarbonate = HCO - 3 Can also be written as Hydrogen Carbonate Biphosphate = HPO 2- 4 Can also be written as Hydrogen Phosphate

+ Naming Molecular Compounds Molecular Compounds – Compounds composed of molecules Low melting & Boiling points (Gas or liquid at room temp) Atoms of 2 or more non-metals Use prefixes to indicate how many atoms are needed in the compound

+ Molecular Compound Naming examples N 2 O Dinitrogen monoxide PCl 3 Phosphrous trichloride SF 6 Sulfur hexaflouride

+ Molecular Compound Naming – YOUR TURN! OF 2 CL 2 O 8 SO 3 Nitrogen triflouride Disulfur dichloride Dinitrogen tetroxide

+ Acids Compounds that produce hydrogen ions when dissolved in water. Anion is connectd to as many hydrogen ions as needed to become electrically neutral. Hydrochloric acid – HCl Sulfuric acid – H 2 SO 4 Nitric acid – Acetic acid – Phosphoric acid – Carbonic acid -