Introduction to Chemistry

Basic Concepts

• Chemistry studies the composition, structure, and properties of substances and their transformations.
• Organic chemistry focuses on carbon-containing compounds.
• Inorganic chemistry studies compounds lacking carbon.
• Analytical chemistry deals with qualitative and quantitative analysis of elements/compounds.
• Physical chemistry examines reaction rates, mechanisms, bonding, and structure.

Matter and States of Matter

• Matter occupies space and has mass.
• Solids have a fixed shape and volume.
• Liquids have a fixed volume but no fixed shape.
• Gases lack a fixed shape or volume.
• Plasma is a collection of charged gaseous particles.

Changes in Matter

• Physical change alters the state/phase without changing chemical composition, such as melting.
• Chemical change alters chemical composition, forming new substances, such as rusting.

Elements and Compounds

• An element is a pure substance that cannot be broken down further.
• A compound consists of two or more elements chemically bonded.

Atoms and Subatomic Particles

• An atom is the smallest unit of an element.
• A proton has a positive charge found in the nucleus.
• A neutron has no charge and is found in the nucleus.
• An electron has a negative charge and orbits the nucleus.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Atomic number refers to the number of protons.
• Mass number refers to the total number of protons and neutrons.

Chemical Bonds

• An ionic bond involves the transfer of electrons, creating charged ions.
• A covalent bond involves the sharing of electrons.
• A metallic bond is an attraction between free electrons and metal ions.

Chemical Reactions

• Reactants are substances that undergo a reaction.
• Products are substances produced by a reaction.
• Synthesis reactions involve combining substances.
• Decomposition reactions involve breaking down substances.
• Single replacement reactions involve one element replacing another.
• Double replacement reactions involve the exchange of ions between two compounds.

Factors Affecting Reaction Rate

• Reaction rate increases with more reactive substances.
• Higher temperature increases reaction rate.
• Higher concentration increases reaction rate.
• More surface area increases reaction rate.
• A catalyst speeds up a reaction without being consumed.

Laws of Chemical Combination

• The Law of Definite Proportions states elements combine in fixed ratios.
• The Law of Multiple Proportions states elements combine in simple whole-number ratios.
• The Law of Combining Weights states elements combine according to their atomic weights.

Stoichiometry

• This is the quantitative relationships in chemical reactions.

Gas Laws

• Boyle's Law: Volume is inversely proportional to pressure at constant temperature.
• Charles' Law: Volume is directly proportional to temperature at constant pressure.
• Combined Gas Law combines Boyle's and Charles' laws.
• Avogadro's Law: Equal volumes of gases contain equal numbers of molecules at the same temperature/pressure.
• Ideal Gas Law: PV = nRT (Pressure × Volume = Moles × Gas Constant × Temperature).
• Graham's Law: Effusion rate is inversely proportional to the square root of molar mass.
• Dalton's Law of Partial Pressure: Total pressure of a gas mixture is the sum of individual gas pressures.

Solutions

• A solute is the substance being dissolved.
• A solvent is the substance doing the dissolving.
• Concentration is the amount of solute in a solution.
• Percent by Mass: (Mass of solute ÷ Total mass) × 100%.
• Percent by Volume: (Volume of solute ÷ Total volume) × 100%.
• Molarity (M): Moles of solute ÷ Volume of solution (L).
• Molality (m): Moles of solute ÷ Mass of solvent (kg).
• Normality (N): Number of equivalents ÷ Volume of solution (L).

Acids and Bases

• Acids donate H+ ions.
• Bases accept H+ ions.
• pH measures acidity (0–7 acidic, 7 neutral, 7–14 basic).

Organic Chemistry

• Alkanes have single bonds.
• Alkenes have double bonds.
• Alkynes have triple bonds.
• Aromatic compounds are cyclic hydrocarbons.

Biological Chemistry

• Carbohydrates serve as an energy source (sugars, starch).
• Proteins consist of amino acids, crucial for growth and repair.
• Nucleic acids, including DNA and RNA, make up genetic material.