Facts for Ionic Formulas

Simple Ionic Compounds Concept: Ionic Formulas are formed from positive and negative ions. Fact 1: Positive ions are formed by metals that lost electrons. These are cations. Examples: Na1+ Mg2+ A3+ P4+ Ca+ion aNion Fact 2: Negative ions are formed by nonmetals that gained electrons. These are anions. Examples: Cl1- O2- N3- Si4- egative

Simple Ionic Compounds Fact 3: We can predict the charges of the main group elements based on where they are on their families. Lose 1e- Gain 2e- Gain 1e- Lose 2e- Lose 3e- Gain 3e- +1 +3 -3 -2 -1 +2

Simple Ionic Compounds Fact 4: The overall charge of ionic compounds must equal zero. Examples : Na1+ Cl1- Ca2+Br1- Al3+O2-

Lesson Two--Polyatomic Ion Formulas Concept: Polyatomic ions are groups of atoms that behave as one unit. Fact 5: Some ions have more that one atom. You will need to memorize most of these but some you can figure out from their atoms. Examples: (SO4) = S +6 and O -8 = -2 (NO3)= N +5 and O -6 = -1 (NH4) = N -3 and H +4 = +1

Polyatomic Ion Formulas Fact 6: These group ions, polyatomic ions, are treated like single ions in formulas, but must have parentheses when more than one is used in a formula. Examples: Ca2+ and (NO3) 1- = Ca(NO3)2 Ga3+ and (SO4) 2- = Ga2(SO4)3 (NH4) 1+ and O2- = (NH4)2O (NH4) 1+ and Cl1- = NH4Cl

Polyatomic Ion Formulas Fact 7: The polyatomic ions are named based on the atoms that they contain. Those with oxygen and another nonmetal are often name "____ate" with the root of the other nonmetal in the blank. Examples: (NO3)1- is nitrate (SO4)2- is sulfate (ClO3) 1- is chlorate

Polyatomic Ion Formulas Fact 8: Those polyatomic ions with one oxygen less than the "ate" ions are named "----ite" ions. Examples: (NO2)1- is nitrite (SO3)2- is sulfite (ClO2)1- is chlorite

Lesson Three--Transition Metal Compounds Concept: Transition metals have electrons in d orbitals and can donate different numbers of electrons, thus giving them several different positive charges. Fact 9: These can be determined from the Roman numeral which is written next to the metal's name. Example: Cu1+is Copper I Pb2+is Lead II Fe3+is Iron III Sn4+s Tin IV

Transition Metal Compounds Fact 10: These transition metals are used in formulas just like other metals, once the charge is determined from the Roman numeral in the name. Example: Cu1+ Cl1- = CuCl Pb2+O2- = PbO Fe3+Br1- = FeBr3 Sn4+O2- = SnO2

Transition Metal Compounds Fact 11: A few transition metal ions only have one charge and never change so they can be written without a Roman numeral in their formula name. Example: Ag1+ Zn2+ Cd2+

Lesson Four--Using Formulas in Problem Solving Concept: Correctly written chemical formulas hold a large amount of information for the prepared student to find. Fact 12: The subscripts tell us the number of atoms of each kind that is present in the compound. Example: NaCl has one atom of sodium and one atom of chlorine. H2SO4 has two atoms of hydrogen, one atom of sulfur and four atoms of oxygen