Science 10: Chemical Reactions

 Name and write formulae for common ionic compounds and molecular compounds and describe the usefulness of the IUPAC nomenclature system (319-1, 114-8)

 All matter is composed of incredibly tiny particles called atoms.  Atoms cannot be created, destroyed, or divided into smaller particles by a physical or chemical change.  Atoms of difference elements bond in definite proportions to form compounds.

 Element – a pure substance that can not be broken down further by physical or chemical means  Atom – the smallest unit of an element that has the properties of that element

 Proton – positive charge  Neutron – neutral charge  Electron – negative charge  In any neutral atom the number of electrons equals the number of protons.  The atomic number of an element is the number of protons that an atom of that element has.

 Compounds are composed of more than one type of element bonded together. Ex. NaCl H 2 O HCl NaOH CO 2  There are 2 main types of compounds: ionic & molecular

 A compound formed of atoms of two or more elements that share electrons.  The smallest independent unit of a molecular compound is a molecule, which are particles of atoms joined together by covalent bonds.

 A compound composed of oppositely charged ions held together with ionic bonds.  An ion is an atom or group of atoms with a positive or negative charge.

 Are composed of ions of two different elements: a positively charged metal ion and a negatively charged non-metal ion

 1. Name the positive ion first by writing the full name of the metallic element.  2. Name the non-metal ion next by dropping the last syllable(s) of the name of the element and adding the suffix "ide.“  Example: Magnesium and Oxygen  Magnesium Oxide

 What would we name a compound of Li and S?

 1. Using the name of the binary compound, write the symbols and charge for the ions involved. Write the ion charge as a superscript. Example: aluminum Oxide — Al 3+ O 2-  2. Put the charges of each ion as the subscript of its partner "cross the charge." Example:  Al 2 3+ O 3 2-  3. As a check to ensure the formula is written correctly, multiply the charge for each ion by the subscript for the same ion. The total positive charge should equal the total negative charge and the net charge per ionic formula should be zero. Example:  A1 3+ x 2 = 6+  O 2- x 3 = 6-  = 0  4. Write the final chemical formula without the charges.  Final Answer: Al 2 O 3

 What is the formula for magnesium chloride?