Bonding and Reactions Test Study Guide Notes

Valence Electrons

• Valence electrons are the outer electrons that connect to other atoms.
• They are important for bonding because they participate in chemical reactions to form chemical bonds.

Number of Valence Electrons

• Aluminum (Al): 3 valence electrons
• Francium (Fr): 1 valence electron
• Argon (Ar): 8 valence electrons

Subscripts and Coefficients in Chemical Formulas

• Subscripts: Indicate the number of atoms of each element in a molecule or formula unit. For example, in H_2O, the subscript 2 indicates there are two hydrogen atoms.
• Coefficients: Indicate the number of molecules or formula units of a substance. For example, 2H_2O means there are two molecules of water.
  • Example: 2Al(OH)_3 indicates 2 aluminum atoms, 6 oxygen atoms, and 6 hydrogen atoms, totaling 14 atoms.
  • Subscript tells you how many of that element there are

Types of Bonds

• Covalent Bonds: Formed between nonmetals.
• Ionic Bonds: Formed between metals and nonmetals.

Diatomic Molecules

• A diatomic molecule is a molecule composed of two atoms of the same element.
• The 7 elements that form diatomic molecules are: Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), and Iodine (I2).

Ions

• An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.
• The charge of an ion is written at the top right with a plus or minus sign.

Ionic Bonds

• Ionic Bond: A chemical bond formed through the electrostatic attraction between oppositely charged ions.
• An ionic bond involves the transfer of electrons.

Cations and Anions

• Cation: A positively charged ion formed when an atom loses electrons.
• Anion: A negatively charged ion formed when an atom gains electrons.

Lewis Dot Diagram

• A Lewis dot diagram shows only the valence electrons of an atom.

Writing Chemical Formulas for Ionic Compounds

• Identify the cation and anion.
• Determine their ionic charges.
• Combine them, and balance the charges to ensure the compound is electrically neutral. An example is not present in the text.

Chemical Equations

• Reactants: The starting materials that are consumed during the reaction.
• Products: The new substances that are formed as a result of a chemical reaction.
• Yield: Refers to the amount of product obtained in a chemical reaction.
• Subscripts: Indicate how many atoms of each element are in the compound.
• Coefficients: Whole numbers placed in front of chemical formulas that indicate how many molecules or moles of a substance are involved in a reaction.
• Example: PbO + 2HCl \rightarrow PbCl2 + H2O

Indications of a Chemical Reaction

• Smell change
• Color change
• Light emission
• Bubbling
• Temperature change

Changes in Properties During Chemical Reactions

• Substances' properties change when they react in a chemical reaction.

Law of Conservation of Mass

• Mass cannot be created or destroyed. In a chemical reaction, the mass of the reactants equals the mass of the products.

Balancing Equations

• Balancing equations is necessary to correctly represent the chemical reaction and ensure that the number of atoms of each element is the same on both sides of the equation, adhering to the Law of Conservation of Mass.

Types of Chemical Reactions

• Synthesis Reaction: Two or more reactants combine to form a single, more complex product.
• Decomposition Reaction: One reactant breaks down into two or more simpler products.
• Single Replacement Reaction: One element replaces another element in a compound.
• Double Replacement Reaction: The cations (positively charged ions) of two compounds switch places, forming two new compounds.
• Combustion Reaction: A substance reacts with oxygen, releasing energy in the form of heat and light.

Exothermic vs. Endothermic Reactions

• Exothermic Reaction: The products have less energy than the reactants; energy is released during the reaction.
• Endothermic Reaction: The products have more energy than the reactants; energy is absorbed during the reaction.

Prefixes for 1-10

• mono- (1)
• di- (2)
• tri- (3)
• tetra- (4)
• penta- (5)
• hexa- (6)
• hepta- (7)
• octa- (8)
• ennea- (9)
• deca- (10)

Naming Ionic Bonds

• Write the name of the cation (positive ion).
• Write the name of the anion (negative ion).

Covalent Bonds

• Electrons are shared in covalent bonds to achieve a stable electron configuration, typically a full outer shell (octet rule) or a stable duplet (for hydrogen).

Naming Covalent Bonds

• Change the last element to Ide.