CHEM 101 Review: Introduction to Chemistry, Matter, the Atom, and Bonding

Module 1: Introduction to Chemistry, Matter, and the Atom

Scientific Method

The scientific method is a systematic approach used to gain knowledge through observation, hypothesis, experimentation, and conclusion.

• Observation: Gathering information using the senses or instruments.

• Hypothesis: A testable explanation or prediction based on observations.

• Experiment: A controlled procedure to test the hypothesis.

• Conclusion: Analysis of results to support or refute the hypothesis.

Law vs. Theory:

• Law: Describes what happens (e.g., Law of Conservation of Mass).

• Theory: Explains why something happens (e.g., Atomic Theory).

Example: Law of Gravity describes the attraction between masses; the theory explains why this occurs.

Significant Figures

Significant figures indicate the precision of a measured number. Rules for determining significant digits:

• Addition/Subtraction: The answer should have the same number of decimal places as the measurement with the fewest decimal places.

• Multiplication/Division: The answer should have the same number of significant figures as the measurement with the fewest significant figures.

Examples:

• 0.00456 has 3 significant figures.

• 1010 has 3 significant figures.

States of Matter

Matter exists in three main states: solid, liquid, and gas. Each state has distinct particle arrangements and properties.

• Solids: Particles are very close together, with very little motion. Solids have a fixed shape and volume.

• Liquids: Particles are close together but have slightly more motion. Liquids take the shape of their container but have a fixed volume.

• Gases: Particles are far apart and have lots of motion. Gases take both the shape and volume of their container.

Physical and Chemical Changes

Physical changes alter the form or appearance of matter without changing its composition. Chemical changes alter the composition, forming a new substance.

• Physical Change: Change in texture, temperature, or shape. Example: breaking a pencil in half.

• Chemical Change: Change in color, formation of bubbles or gases, cannot be returned to starting material. Example: burning a pencil in a fire pit.

Classification of Matter

Matter can be classified as pure substances or mixtures.

• Pure Substance: Matter with a fixed or definite composition (element or compound).

• Element: Composed of only one type of material.

• Compound: Two or more elements chemically combined.

• Mixture: Physically combined substances.

• Homogeneous Mixture: Uniform composition throughout.

• Heterogeneous Mixture: Varying composition within the mixture.

Examples:

• NaHCO3: Compound

• Rust: Compound

• Air: Mixture

• Ice: Compound

Atomic Structure

Atoms are composed of three subatomic particles:

• Proton: Positively charged, located in the nucleus.

• Neutron: No charge, located in the nucleus.

• Electron: Negatively charged, located outside the nucleus.

The identity of an element is determined by the number of protons.

Cation vs. Anion:

• Cation: Positively charged ion, loss of electrons.

• Anion: Negatively charged ion, gain of electrons.

The Periodic Table

The periodic table organizes elements by increasing atomic number and groups elements with similar properties.

• Group: Vertical columns (e.g., Group 1: Alkali metals, Group 17: Halogens).

• Period: Horizontal rows.

• Metals: Left/middle of the table.

• Nonmetals: Right side.

• Metalloids: B, Si, Ge, As, Sb, Te, Po.

Periodic Trends:

• Atomic Size: Increases down a group, decreases across a period.

• Ionization Energy: Energy required to remove a valence electron; increases across a period.

• Electronegativity: Tendency to attract electrons; increases across a period, highest in fluorine (F).

Trend	Direction of Increase
Atomic Size	Down a group, left across a period
Ionization Energy	Up a group, right across a period
Electronegativity	Up a group, right across a period

Vocabulary Review – Module 1

• Scientific Method: Process used to gain knowledge through observations, hypotheses, experiments, and conclusions.

• Hypothesis: Testable explanation or prediction.

• Theory: Explains why or how something happens.

• Law: Describes what happens.

• Significant Figures: Indicates precision of a number.

• Physical Property/Change: Change in form or appearance without changing composition.

• Chemical Property/Change: Change to a new or different substance.

• Pure Substance: Matter with a fixed or definite composition.

• Element: Simplest type of pure substance, only one kind of material.

• Compound: Chemically combined two or more elements.

• Mixture: Physically combined two or more elements/compounds.

• Proton: Positively charged, in nucleus, atomic #.

• Neutron: Neutral, in nucleus, changes atomic mass.

• Electron: Negatively charged, outside nucleus, changes charge of element.

• Atomic Number: Determined by number of protons.

• Mass Number: Protons + neutrons.

• Isotope: Element with a variable number of neutrons.

• Ion: Element with a variable number of electrons.

• Valence Electron: Outermost electron, used in bonding.

• Periodic Table: Ordered arrangement of chemical elements.

• Group Number: Vertical columns.

• Period Number: Horizontal rows.

• Electronegativity: Tendency to attract electrons.

Module 2: Bonding and Naming Compounds

Types of Bonds

Chemical bonds hold atoms together in compounds. The two main types are ionic and covalent bonds.

• Ionic Bond: Formed between metals and nonmetals; involves transfer of electrons.

• Covalent Bond: Formed between nonmetals; involves sharing of electrons.

The Octet Rule

Atoms bond to achieve eight electrons in their valence shell, similar to noble gases. Exceptions include hydrogen (H), helium (He), and boron (B).

Ions and Charges

Ions are atoms or molecules with a net electric charge due to loss or gain of electrons.

• Cation: Positively charged ion (loss of electrons).

• Anion: Negatively charged ion (gain of electrons).

Examples:

• Calcium: Ca2+

• Sulfur: S2−

• Gallium: Ga3+

• Fluorine: F−

Naming Ionic Compounds

Ionic compounds are named by identifying the cation and anion. Transition metals use Roman numerals to indicate charge.

• Name metal using periodic table.

• If transition metal, use Roman numerals for charge.

• Name nonmetal with "-ide" ending.

• Use polyatomic ion chart for compounds containing polyatomic ions.

Examples:

• MgCl2: Magnesium chloride

• BaI2: Barium iodide

• FeO: Iron(II) oxide

Polyatomic Ions

Polyatomic ions are ions composed of two or more elements with a specific charge.

• Compounds with polyatomic ions are named using the chart provided.

Naming Molecular (Covalent) Compounds

Molecular compounds are named by:

• Naming the first nonmetal.

• Naming the second nonmetal with "-ide" ending.

• Adding prefixes to indicate the number of atoms (e.g., mono-, di-, tri-).

Examples:

• CS2: Carbon disulfide

• P2O5: Diphosphorus pentoxide

• NCl3: Nitrogen trichloride

Organic Chemistry Basics

Organic compounds are molecules that contain carbon and hydrogen.

• Alkanes: Named using the "-ane" ending, with a prefix based on the number of carbons (e.g., methane, ethane).

Elements in Organic Compounds: Carbon (C) and Hydrogen (H).

Vocabulary Review – Module 2

• Bond: Force that holds elements together.

• Ionic Bond: Transfer of electrons from metals to nonmetals.

• Covalent Bond: Sharing of electrons between nonmetals.

• Octet Rule: Atoms bond to have 8 electrons in their valence shell.

• Cation: Positively charged ion.

• Anion: Negatively charged ion.

• Polyatomic Ion: Ion composed of two or more elements with a specific charge.

Additional info: These notes cover foundational topics from GOB Chemistry chapters 1 and 2, including matter, atomic structure, the periodic table, chemical bonding, and basic organic chemistry nomenclature. All definitions, examples, and rules are expanded for clarity and completeness.