Chapter 5 - Chemical Names and Formulas
Chapter 5: Chemical names and formulas
Periodic table [Reference]
Atoms and Ions
The Law of Multiple Proportions
Ionic charges of the elements
Common and systematic names
Writing formulas for binary ionic compounds
Naming binary ionic compounds
Ternary ionic compounds
Binary molecular compounds
5-1 The Periodic Table
- Elements are arranged on the periodic table according to similarities, trends, and patterns in their properties.
- Groups are vertical columns; periods are horizontal rows.
- Metals on the left, nonmetals on the right.
- See Chempire's
Online Periodic Table
5-2 Atoms and Ions
- Ions are atoms that have either gained or lost one or more electrons, and therefore have a charge.
- Cations have a positive charge, anions have a negative charge.
- Law of Definite Proportions: In any chemical compound the elements are always combined in the same proportion by mass.
- A molecule is a group of atoms.
5-4 Chemical Formulas
- A chemical formula is a recipe for the compound.
- A molecular formula is a recipe for the molecule.
- A formula unit is a recipe for an ionic compound.
5-5 The Law of Multiple Proportions
- If two elements can combine in different ways to produce different compounds, the different masses of one of the elements are in a small, whole-number ratio.
5-6 Ionic Charges of the Elements
- Each group has its own ionic charge. Elements from group 1 have a charge of +1 when they form ions, +2 from group 2, -3 from group 5, -2 from group 6, -1 from group 7.
- Transition Metals have multiple possible ionic charges. See Chempire's Online Transition Metal Charge Chart
5-7 Polyatomic Ions
- A polyatomic ion is a tight group of atoms that carries a collective ionic charge and can participate as either the cation or anion in an ionic compound.
- See Chempire's
Online Polyatomic Ion Chart.
5-8 Common and Systematic Names
- Systematic names are better than common names.
5-9 Writing Formulas for Binary Compounds
- Binary compounds involve two elements.
- Cation (left side of periodic table) goes first, anion (right side of periodic table) comes second, with its name ending in -ide.
- You must then add subscripts (the little numbers below and to the right of a symbol) to balance out the compounds electric charge.
- Calcium becomes Ca^(2+). Bromine becomes Br^(-). Therefore, you need 2 bromides for every 1 calcium to keep the compound neutral: CaBr2.
5-10 Naming Binary Ionic Compounds [Practice]
- Cation followed by anion-ide.
- For transition metals: Charge (always positive) goes right after the cation, in parenthesis, using roman numerals. Examples: copper(I), cobalt(II).
5-11 Ternary Ionic Compounds
- Ternary ionic compounds involve 3 elements. Usually they make use of a polyatomic ion.
5-12 Binary Molecular Compounds [Practice]
- Rules: put prefixes in front of both ions that describe the subscripts after each. The exception is that a
"mono-" before the cation can can dropped. See Chempire's
Online Molecular Compounds Prefixes Chart.
[Naming with Polyatomic Ions]
More Practice: [Naming with Transition Metals]
More Practice: [
Naming with Hydrates]
5-13 Acids [Practice
- Acids release hydrogen ions when you dissolve them in water.
- Acid chemical formulas usually start with H as the cation. If the anion ends in -ide, the acid name begins
with "hydro-" and ends with "-ic acid." If the anion ends in -ite, the acid name ends with "-ous acid." If the
anion ends in -ate, the acid name ends with "-ic acid."
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