1. COMPOUNDS Integrated Physics and Chemistry

2. COMPOUNDS 1. A compound is made of two or more elements that are chemically joined in definite proportions. 2. Compounds are formed when a positive (+) ion joins with a negative (-) ion. Compounds usually do NOT look or react like the elements from which they are made. All atoms would like to have a full outer shell like the Noble Gases. (8 valence electrons) An ion is an atom with a charge because it lost or gained electrons trying to fill it's outer shell. An ion is an atom with a charge because it lost or gained electrons trying to fill it's outer shell.

3. COMPOUNDS FamilyUsuallyValence 1Alose 1 electron+1 2Alose 2 electrons+2 13Alose 3 electrons+3 14Alose 4 electrons-4 +4 15Again 3 electrons-3 16Again 2 electrons-2 17Again 1 electron 18Ado not reactzero 3. Oxidation Number another term for valence or charge. Metals usually lose electrons = (+) ions Nonmetals usually gain electrons = (-) ions

4. COMPOUNDS 4. Compounds are held together by bonds. Ionic Bond -* formed between metals (+) and nonmetals (-) * one atom loses electrons (+) * the other atom gains electrons (-) Covalent Bond -* electrons are SHARED among atoms * can occur between 2 nonmetals 5. Metals with more than one possible valence charge are called variable valence metals. Metals with only one possible valence are called nonvariable valence metals.

5. COMPOUNDS 6.Whether you are writing the name or the formula for a compound, the positive ion is always written first. MgSO 4 Ba 3 (PO 4 ) 2 NaCl NaCl Fe 2 O 3 Fe 2 O 3

6. COMPOUNDS 7. There are two classes of compounds Binary compounds contain only 2 elements. Polyatomic compounds contain 3 or more elements. Polyatomic compounds contain at least one polyatomic ion. A polyatomic ion is a group of atoms which behave as a single ion.

7. COMPOUNDS 8. Naming Binary Compounds (a) Name the positive (+) ion (b) Name the negative (-) ion and change its ending to "ide" (c) Decide if the metal needs a Roman Numeral (c) Decide if the metal needs a Roman Numeral. 9. Naming Polyatomic Compounds (a) Name the positive (+) ion (b) Name the polyatomic (-) ion (c) Decide if the metal needs a Roman Numeral. (c) Decide if the metal needs a Roman Numeral.

8. COMPOUNDS 10. Compounds can be written as chemical formulas. A chemical formula is a group of symbols and subscripts which tell you (a) Which elements are present. (b) How many of each element are present. 11. A subscript is a small number, written behind and slightly lower than the symbol of an element. A subscript indicates how many ions of that element are present. A subscript of one (1) is never used.

9. COMPOUNDS 12. A covalent compound forms between two nonmetals. These compounds occur because the nonmetals will share electrons to have a full last energy level. Since electrons are not lost or gained, the atoms are not considered ions, so they do not have a charge.

10. COMPOUNDS Because covalent compounds aren’t made of ions, you can’t use the oxidation number to predict how many atoms of each element are going to be in a covalent compound. Because covalent compounds aren’t made of ions, you can’t use the oxidation number to predict how many atoms of each element are going to be in a covalent compound. The following prefixes will be used. The following prefixes will be used. mono-onehexa-six di-twohepta-seven tri-threeocta-eight tetra-fournona-nine penta-fivedeca-ten

11. COMPOUNDS Name the first element in the compound, and use a prefix if there is more than one of the element. Name the first element in the compound, and use a prefix if there is more than one of the element. Name the second element, end in –ide, and put a prefix at the beginning even if there is only one. Name the second element, end in –ide, and put a prefix at the beginning even if there is only one. EXAMPLES EXAMPLES CO 2 – Carbon Dioxide CO 2 – Carbon Dioxide CO – Carbon Monoxide CO – Carbon Monoxide N 2 O – Dinitrogen Monoxide N 2 O – Dinitrogen Monoxide