General Chemistry Foundations: Periodic Table, Matter, and Measurement

Basics of the Periodic Table

Arrangement of the Periodic Table: Periods vs. Groups

The periodic table is a systematic arrangement of chemical elements based on their atomic number, electron configuration, and recurring chemical properties.

• Periods: Horizontal rows (numbered 1-7). Elements in the same period have the same number of electron shells.

• Groups: Vertical columns (numbered 1-18). Elements in the same group have similar chemical properties due to similar valence electron configurations.

Properties of Metals and Nonmetals

• Metals: Typically shiny, malleable, ductile, good conductors of heat and electricity, and tend to lose electrons to form cations.

• Nonmetals: Usually dull, brittle, poor conductors, and tend to gain electrons to form anions.

Families of Elements

Certain groups in the periodic table are known as element families, each with characteristic properties.

• Alkali Metals (Group 1): Highly reactive, soft, low melting points, one valence electron.

• Alkaline Earth Metals (Group 2): Reactive, harder than alkali metals, two valence electrons.

• Transition Metals (Groups 3-12): Variable oxidation states, form colored compounds, good conductors.

• Lanthanide Series: Rare earth metals, f-block, used in electronics and magnets.

• Actinide Series: Radioactive, f-block, includes uranium and thorium.

• Halogens (Group 17): Very reactive nonmetals, form salts with metals.

• Noble Gases (Group 18): Inert, colorless, odorless gases with full valence shells.

Chemistry

Definition of Chemistry & Chemical

Chemistry is the scientific study of matter, its properties, composition, structure, and the changes it undergoes during chemical reactions. A chemical is any substance with a defined composition.

Branches of Chemistry and Types of Chemical Research

• Organic Chemistry: Study of carbon-containing compounds.

• Inorganic Chemistry: Study of non-organic compounds, including metals and minerals.

• Physical Chemistry: Study of the physical properties and behavior of matter.

• Analytical Chemistry: Techniques for analyzing substances.

• Biochemistry: Chemistry of living organisms.

• Chemical Research: Can be basic (fundamental understanding) or applied (practical applications).

Nuclear vs. Chemical Reactions

• Chemical Reactions: Involve rearrangement of electrons; atoms retain their identity.

• Nuclear Reactions: Involve changes in the nucleus; can change one element into another.

Atoms, Molecules, and Formula Units

• Atom: The smallest unit of an element retaining its chemical properties.

• Molecule: Two or more atoms bonded together (e.g., H2O).

• Formula Unit: The simplest ratio of ions in an ionic compound (e.g., NaCl).

Matter

Definition and Examples of Non-Matter

Matter is anything that has mass and occupies space. Non-matter includes things like light, heat, and sound, which do not have mass or volume.

Properties: Physical vs. Chemical, Intensive vs. Extensive

• Physical Properties: Can be observed without changing the substance (e.g., color, melting point).

• Chemical Properties: Describe how a substance reacts (e.g., flammability).

• Intensive Properties: Do not depend on amount (e.g., density, boiling point).

• Extensive Properties: Depend on amount (e.g., mass, volume).

States of Matter

• Solid: Particles packed closely, definite shape and volume, strong attractive forces.

• Liquid: Particles less tightly packed, definite volume, indefinite shape.

• Gas: Particles far apart, indefinite shape and volume, weak attractive forces.

Changes of Matter: Physical vs. Chemical, Changes of State

• Physical Change: Alters form but not identity (e.g., melting, boiling).

• Chemical Change: Produces new substances (e.g., rusting, combustion).

• Changes of State:

  • Melting: Solid to liquid

  • Deposition: Gas to solid

  • Other changes: Sublimation, condensation, evaporation, freezing

Mixtures vs. Pure Substances

• Pure Substance: Has a fixed composition (element or compound).

• Mixture: Physical blend of two or more substances.

• Homogeneous Mixture: Uniform composition (solution).

• Heterogeneous Mixture: Non-uniform composition (e.g., salad).

Significant Figures & Scientific Notation

Rounding for Specific Numbers of Significant Figures

• Significant figures (sig figs) reflect the precision of a measurement.

• When rounding, keep only the required number of digits, starting from the leftmost nonzero digit.

Scientific Notation and Significant Figures

• Scientific notation expresses numbers as a product of a coefficient and a power of ten: $a imes 10^n$

• When converting to or from scientific notation, maintain the same number of significant figures.

Math with Significant Figures

• Multiplication/Division: Round to the least number of sig figs in any factor.

• Addition/Subtraction: Round to the least number of decimal places.

Phase Diagrams

Definition of STP

• STP (Standard Temperature and Pressure): Defined as 0°C (273.15 K) and 1 atm pressure.

Location of States of Matter on a Phase Diagram

• A phase diagram shows regions of solid, liquid, and gas as a function of temperature and pressure.

• Boundaries indicate phase transitions (e.g., melting point, boiling point).

Identifying States and Physical Changes

• At a given temperature and pressure, the phase diagram indicates the state of matter present.

• Changing temperature or pressure can cause transitions such as melting, boiling, or sublimation.

Example: Interpreting a Phase Diagram

• If a substance is at a point above the melting line but below the boiling line, it is a liquid.

• Increasing pressure at constant temperature may cause a gas to condense into a liquid.

Additional info:

• Phase diagrams may include triple points (where all three states coexist) and critical points (beyond which liquid and gas are indistinguishable).