CHEM 151: Review Exam I Study Guide – Fundamental Concepts in GOB Chemistry

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Understanding the basic SI units and measurement techniques is essential in chemistry for quantifying physical properties.

SI Units: The standard units for measurement in chemistry are: - Mass: kilogram (kg) - Volume: liter (L) - Length: meter (m) - Temperature: kelvin (K) - Time: second (s)
Measured vs. Exact Numbers: - Measured numbers are obtained from measurements and have uncertainty (e.g., 5.52 cm, 8.456 m). - Exact numbers are defined values or counted quantities (e.g., 1 dozen = 12, 2 branches on a tree).
Significant Figures: Indicate the precision of a measured value. Zeros may be significant or not, depending on their placement. - Example: has three significant figures.
Scientific Notation: Used to express very large or small numbers. - Example: in scientific notation is .

Unit conversions are performed using conversion factors to ensure consistency in calculations.

Equality and Conversion Factors: An equality relates two units (e.g., 1.50 x 103 g = 1.50 kg). Conversion factors are derived from these equalities.
Density: Density is mass per unit volume. - Formula:
Specific Gravity: Ratio of the density of a substance to the density of water. - Formula:
Medication Dosage Calculations: Use dimensional analysis to convert between units (e.g., mg, tablets).

Chemistry classifies matter based on its composition and properties.

Pure Substance: Matter with a fixed composition (element or compound).
Mixture: Physical blend of two or more substances; can be homogeneous (uniform) or heterogeneous (non-uniform).
Element: Substance made of only one type of atom (e.g., copper, sodium).
Compound: Substance composed of two or more elements chemically combined (e.g., water, sodium chloride).
Classification Table:

Type	Description	Example
Element	Single type of atom	Copper (Cu)
Compound	Two or more elements chemically bonded	Water (H2O)
Homogeneous Mixture	Uniform composition	Salt water
Heterogeneous Mixture	Non-uniform composition	Salad

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

Atomic Number (Z): Number of protons in the nucleus.
Mass Number (A): Total number of protons and neutrons. - Formula: (where N = number of neutrons)
Isotopes: Atoms of the same element with different numbers of neutrons.
Electron Configuration: Arrangement of electrons in orbitals around the nucleus.
Example: Sodium atom with atomic number 11 and mass number 24 has 11 protons, 13 neutrons, and 11 electrons.

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

Groups/Families: Vertical columns; elements in the same group have similar chemical properties.
Periods: Horizontal rows; indicate the number of electron shells.
Element Symbols: Each element is represented by a unique one- or two-letter symbol (e.g., Na for sodium).
Common Elements: Li, Na, K, Ca, Al, N, O, P, S, Cl, Br, F, I, Cs, Zn, Cu, Mg, Hg, Ca.
Electron Energy Levels: Electrons occupy energy levels (shells) around the nucleus. Each level can hold a specific number of electrons. - Formula: (where n = energy level)
Orbitals: Regions of space where electrons are likely to be found (s, p, d, f).
Example: The 5p orbital of silicon can hold up to 6 electrons.

Understanding the difference between physical and chemical changes is fundamental in chemistry.

Physical Change: Change in state or appearance without altering composition (e.g., melting, boiling).
Chemical Change: Change that produces new substances (e.g., rusting, combustion).
Example: Burning magnesium ribbon is a chemical change; melting ice is a physical change.

Clear definitions of key terms are crucial for understanding chemistry concepts.

Some questions reference specific calculations (e.g., medication dosages, density, specific gravity) that require dimensional analysis and conversion factors.
Questions about atomic structure and periodic table organization are foundational for GOB Chemistry.