Chapter 5: Chemical Names
and Formulas
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Introduction: Elements are the building materials of all living and nonliving things.
5.1 The Periodic Table
1. In the periodic table elements are arranged according to similarities in their properties.
2. Elements organized in order of increasing atomic number.
3. Each column in the table is a group (family).
4. Group A elements are representative elements - metals, metalloids, and nonmetals.
5. Elements on left are metallic.
6. Metals are elements that have a high electrical conductivity and a high luster when clean. Ductile, malleable.
7. All metallic elements are solids at room temperature (except Hg).
8. Transition metals are Group B elements.
9. Inner transition metals are also called rare earths.
10. The nonmetallic elements occupy the upper right corner of the periodic table. Nonmetals are nonlustrous and are poor conductors. Some are gases (Ar, Cl, O). Some are solids (C, P). Some are liquids (Bromine). H is a nonmetal, but listed in column 1A.
11. 1A - Alkali metals (except H is not a metal)
12. 2A - Alkaline earth metals
13. 3A, 4A, 5A, 6A, 7A - Nonmetals
14. Last column - Noble gases.
15. Metalloids are on either side of stair "stair-step" - Have properties of nonmetals and metals (Si, Ge)
16. Do concept practice 1, 109.
5.2 Atoms and ions.
1. Ion - atoms or groups that have positive or negative charge due to loss or gain of electrons. E.g. Na
2. Cation is any atom or group with positive charge. E.g., Na, Mg
3. Metallic cations is same as element.
4. Anions are atoms or groups with a negative charge. Gained electrons.
5. E.g., Cl -, O2-, S2-
6. Nonmetallic elements tend to form anions. Anions are named with suffix -ide.
5.3 Compounds
1. Compound is two or more different elements combined chemically.
2. Molecule is an electrically neutral group of atoms that act as a unit.
3. Molecular compounds are compounds composed of distinct molecules.
4. Low melting and boiling points (below 300oC. Often liquids or gases at room temperature. E.g., water, carbon dioxide.
5. Molecular compounds are composed of nonmetallic elements.
6. Ionic compounds are composed of positive cations and negative anions.
7. Uses formula unit, but no distinct separate molecules. Entire compound is electrically neutral.
8. High mp and bp (above 300oC). Solids at room temp.
9. Formed from metallic and nonmetallic elements.
5.4 Chemical Formulas
1. Chemical formula shows the kinds and numbers of atoms in the smallest representative unit of the substance.
2. Molecular formula shows the number and kinds of atoms present in a molecule of a compound. (pictures page 113)
3. Some elements exist as molecules. (Figure 5.9, page 114). Know these.
4. Formula Unit is the lowest whole-number ratio of ions in an ionic compounds.
5. Ionic charges are used to derive formula, but are not written in formula.
6. See table 5.1, page 115 for property difference between ionic and molecular compounds.
7. Go over 8 & 9, page 115
5.5 Skip
5.6 Ionic Charges of the Elements
1. To form formulas for ionic compounds, need charges. Representative elements (As) easy.
2. Metallic elements lose electrons to form cations.
3. Columns 1, 2, & 3, lose that number of electrons to form +1, +2, +3 ions. (3A use Al, only)
4. Group A nonmetals - subtract group number from 8. (Use for groups 5A,6A,7A) Use negative sign, since nonmetals gain electrons. E.g., Cl, F, O, etc.
5. Groups 4A, 8A don't form ions. 4A C and S are found in molecular compounds. 8A elements are inert.
6. Transition metals (B) have more than one ionic charge (most). E.g., Fe2+, Fe3+.
7. Naming of compounds uses stock system - roman numerals or root word -ous for low or -ic for high. See table 5.3, page 120.
8. A few transition metals ("exceptions") have only one ionic charge> Ag+, Cd2+, Zn2+. They don't need a roman numeral.
5.7 Polyatomic ions
1. Monatomic ions are formed from single atoms.
2. Polyatomic ions are tightly bound groups of atoms that behave as a unit and carry a charge. E.g., SO42- . See table 5.4, page 123.
3. Most polyatomic ions end in -ite = lowest. -ate = highest.
4. Exceptions = Ammonium cation Nh4+, cyanide CN-, hydroxide OH-.
5. When H+ is combined with polyatomic ion, charge is algebraic sum of ionic charges. See page 123.
5.8 Common and Systematic Names
5.9 Writing Formulas for Binary Ionic Compounds.
1. Monatomic + Monatomic. Cation + anion. Compound's net charge is 0.
5.10 Naming Binary Ionic Compounds.
1. Metal + anion + -ide.
2. Use roman numerals for transition elements. Do not use for 1A, 2A, 3A.
5.11 Ternary Ionic Compounds.
1. Metal + Polyatomic anion + -ite or -ate.
2. 3 different atoms. E.g., Ca(NO3)2
3. Name "recognize" polyatomic anion 1st. Then name.
5.12 Binary Molecular Compounds
1. 2 nonmetallic elements.
2. Composed of "molecules", not formula units.
3. Use prefixes table 5.5, page 131.
4. Names of binary compounds (ionic and molecular) end in -ide.
5. Mono is omitted if single atom is 1st.