Chemistry Naming and Formulas Quiz

Chemical Formulas and Equations

• Chemical formulas represent the proportions of atoms in a compound or molecule.
• Chemical formulas use symbols for elements and numbers to indicate the count of each atom.
• Parentheses, brackets, dashes, dots, plus (+), and minus (-) signs sometimes accompany these symbols and numbers.

Learning Goals/Objectives

• Review monoatomic and polyatomic radicals (tables and formula writing)
• Understand parts of a chemical equation
• Understand types of chemical equations
• Convert word equations to chemical equations
• Convert chemical equations to word equations
• Balance chemical equations
• Memorize solubility rules
• Write ionic/precipitation reactions
• Balance ionic reactions
• Define, identify, and delete spectator ions
• Write net ionic reactions

Compounds, Elements, and Atoms

• A compound is formed when two or more elements are chemically bonded. Example: Water (hydrogen and oxygen).
• An element is a substance whose atoms all have the same number of protons (same atomic number).
• An atom is the smallest unit of an element, comprised of a nucleus and orbiting electrons

Parts of a Chemical Formula

• Coefficient: A number placed before a formula, indicating the molecule(s) number.
• Element: A symbol representing an element (e.g., Ca)
• Parenthesis: Used to group multiple atoms
• Subscript: A number placed after an element symbol, indicating the number of atoms.

Water of Crystallization

• A dot in a chemical formula represents weak bonds formed by water to the compound.
• This weak bonding is called water of crystallization.
• Heating breaks these bonds, releasing water as moisture/steam.

Writing Formulas for Ionic Compounds

• Ionic compounds are comprised of positive and negative ions.
• Metal cation and nonmetal anion combination
• The sum of cation charges equals the sum of anion charges.
• Subscripts are determined from the magnitude of the charges.

Steps for Writing Ionic Formulas

• 1. Write the metal symbol/charge followed by the nonmetal symbol/charge
• 2. Exchange the magnitudes of the charges to become subscripts (switch values).
• 3. If a polyatomic anion/cation has a charge greater than +/-1, enclose it in parentheses and use the magnitude of the charge on the other ion as the subscript.
• 4. Simplify numerical subscripts to give the smallest whole-number ratio.
• 5. Verify the sum of the charges are equal in the compound.

Naming Ionic Compounds

• The name consists of the cation (metal) name followed by the anion (non-metal) name ending in -ide.

Use of Suffixes in Ionic Compounds

• -ide: two elements present (example: lead oxide (PbO))
• -ate: three or more elements present, with O as one element (example: calcium carbonate (CaCO3))
• Bi-: used in names to indicate the presence of 2 as a number within the molecule (example: nitrogen dioxide)(CO2)

Rules Continued

• Switch charges.
• Bracket polyatomic ions with a charge greater than +1/-1
• Cancel out charges with matching numerical magnitude.
• Write the compound name without charges.

Types of Chemical Equations

• Synthesis: Two or more reactants form a single product (example: 2H2 + O2 → 2H2O).
• Decomposition: A single reactant breaks down into two or more products (example: 2HgO → 2Hg + O2).
• Single Replacement: One element replaces another element in a compound (example: Zn + 2HCl → ZnCl2 + H2).
• Double Replacement: The ions of two compounds exchange places in a reaction (example: AgNO3 + NaCl → AgCl + NaNO3).

Chemical Change vs. Physical Change

• A chemical change results from a chemical reaction, changing the substance's chemical identity.
• A physical change results from a physical change without changing the substance's chemical identity.

What is a Chemical Reaction?

• Reactants change chemically to form new products.
• The equation indicates the reactants and products formed.
• State symbols (s, l, g, aq) identify whether a substance is a solid, liquid, gas, or dissolved in water (aqueous).

Definition of a Chemical Equation

• A chemical equation describes a chemical reaction symbolically.
• Reactants are on the left side, products on the right separated by an arrow.

Parts of a Chemical Equation

• Reactants and products: the elements/compounds undergoing and resulting from the reaction respectively.
• Coefficients: the numbers before the elements/compounds that balance the number of atoms on each side of the reaction.
• Subscripts: the numbers after the elements indicating the number of atoms for each element.
• State symbols (s, l, g, aq): physical states (solid, liquid, gas, aqueous solution).

Conditions in Chemical Reactions

• Specific temperatures, pressures, and catalysts can be shown in the reaction to specify conditions necessary for the reaction to happen

Understanding it Better

• Law of conservation of mass: matter cannot be created nor destroyed.
• Mass of reactants = mass of products

Converting Chemical Equations to Word Equations

• Translate the chemical formulas into compound names.
• Insert appropriate words to form complete sentences stating reactants forming products.

Solubility Rules

• Rules for determining the state of a substance in a reaction.
• Metals (typically solid) except mercury (liquid).
• Diatomic nonmetals (always gases except I2, solid; Br2, liquid).
• Acids (always aqueous).
• Solubility is reviewed using a solubility table (when necessary for salts and bases, which are often aqueous if soluble in water)

Ionic Equations

• Represents ions participating in a reaction.
• Spectator ions are those that don't participate in the reaction and are omitted from the net ionic equation.

Steps for Writing Balanced Ionic Equations

• Write the balanced molecular equation.
• Identify the states of reactants and products.
• Dissociate all aqueous solutions into their ionic components.
• Cancel spectator ions (ions that appear on both sides of the equation).
• Write the net ionic equation (only showing the ions that react).

Characteristics of a Balanced Ionic Equation

• Numbers of atoms, overall charge on both sides of the equation (are both zero).

Covalent Compounds

• Compounds where atoms share electrons to achieve a more stable electron configuration
• Covalent compounds are formed by atoms that aren't metals.
• Carbon can form 4 covalent bonds.
• The formula represents the number of atoms of each element in one molecule.
• Use prefixes in the name to show the number of atoms (e.g., carbon dioxide CO2)

Prefix Table

• Useful for naming covalent compounds (e.g mono, di, tri...).

Writing Formulas for Covalent Compounds

• Determine the number of atoms of each element.
• Write the chemical formula with the symbol for the central atom first.
• Insert subscripts for elements after.
• Use prefixes from the prefix chart to name the covalent compound using the appropriate prefix followed by the elements (e.g. carbon dioxide CO2).

Popular Acids and Bases

• Memorize their formulas and names.
• Some have special names like acids and bases.

Diatomic Molecules

• Molecules containing two atoms of the same element.
• Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), Iodine (I2).