Chemical Reactions

Writing Chemical Formulas Steps for writing: 1.Decide the type of bond – a)Prefixes used– Covalent Bond b)No prefixes– Ionic 2.Write the symbol of the element or polyatomic ion. 3.Add a subscript IF a prefix was used, OR if needed to balance charges.

Writing Chemical Formulas 4.Write the symbol of the second element or polyatomic ion 5.Add a subscript IF a prefix is used OR if needed to balance charges. Examples: Lithium nitride Potassium sulfate

Writing Ionic Names Steps for writing: 1.Decide the type of bond – a)2 nonmetals – Covalent Bond b)A metal and a nonmetal, OR has a polyatomic ion – Ionic 2.Find the oxidation numbers for each element or ion 3.Write the symbol of the element or polyatomic ion that is positive

Writing Ionic Names 4.Write the root name for the negative ion. 5.Add –ide to the end of the last element UNLESS it is a polyatomic ion (page 619) i.Examples: Na 3 PO 4 ii.CuCl iii.AlCl 3

Writing Covalent Names Steps for writing: 1.Decide the type of bond – a)2 nonmetals – Covalent Bond b)A metal and a nonmetal, OR has a polyatomic ion – Ionic 2.Add a prefix (if needed) to the name of the first element listed. 3.Add a prefix (if needed) to the ROOT of the name of the second element listed 4.Add –ide to the end of the last element.

Examples of Covalent Bonds 1.Nitrogen oxide 2.Nitrogen dioxide 3.Dinitrogen pentoxide 4.Carbon monoxide 5.Carbon dioxide

Hydrates A compound that has water chemically attached to its ion EX – Calcium sulfate dihydrate CaSO 4 * 2 H 2 O

Chemical Changes Chemical reaction – 1 or more substances are converted into new substances Chemical reactant – – The substances that react in a chemical reaction (left side of the equation) Chemical Products – The substances that are made in a chemical reaction (right side of the equation)

Chemical equation Law of Conservation of Mass – Mass is neither created or destroyed; it only changes form What does this mean? – The amount of matter AND the number of elements used is the same on BOTH sides of a reaction.

Lavoisier French tax collector Proved the Law of Conservation of Mass Proved the Law of Conservation of Matter

Writing Equations Chemical equation – “texting” way to write chemical reactions NiCl 2 (aq) + 2Na(OH) 2 (aq) Ni(OH) 2 (s) + 2NaCl (aq) Common symbols (see page 635) Coefficients – number of units needed in a reaction