Introduction to Chemistry

• Chemistry is the study of matter and its properties as well as how matter changes.

Branches of Chemistry

• Analytical chemistry studies the chemical components and composition of matter.
• Biochemistry studies chemical processes within and relating to living organisms.
• Inorganic chemistry studies the properties and behavior of inorganic compounds.
• Organic chemistry studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds.
• Physical chemistry applies physics to the study of chemical systems and processes.

Matter

• Matter is anything that has mass and takes up space.
• Matter exists in different states including solid, liquid, gas, and plasma.

Elements

• An element is a substance that cannot be broken down into simpler substances by chemical means.
• Elements are arranged on the periodic table by increasing atomic number.
• The periodic table organizes elements with similar properties into groups and periods.
• Metals, nonmetals, and metalloids are the three main types of elements.

Compounds

• A compound is a substance consisting of two or more different elements chemically bonded together in a fixed ratio.
• Compounds can be represented by chemical formulas, which indicate the type and number of each atom in a molecule of the compound.
• Ionic compounds are formed through ionic bonds, held together by electrostatic forces between oppositely charged ions.
• Covalent compounds are formed through covalent bonds, when atoms share one or more pairs of electrons.

Mixtures

• A mixture is a combination of two or more substances that are physically combined.
• Mixtures can be homogeneous, where the composition is uniform throughout, or heterogeneous, where the composition varies throughout.
• Techniques like filtration, distillation, and chromatography can separate mixtures based on differences in physical properties.

Atoms

• An atom is the smallest unit of an element that retains the chemical properties of that element.
• Atoms are composed of protons, neutrons, and electrons.
• Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.
• The number of protons determines the element's atomic number.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Ions are atoms or molecules that have gained or lost electrons, resulting in a net electric charge.

Chemical Bonds

• A chemical bond is an attraction between atoms that allows the formation of chemical substances.
• Ionic bonds are formed through the transfer of electrons between atoms.
• Covalent bonds are formed through the sharing of electrons between atoms.
• Metallic bonds are found in metals, where electrons are delocalized and shared among many atoms.
• Hydrogen bonds are weak attractions between hydrogen atoms and highly electronegative atoms like oxygen, nitrogen, or fluorine.

Chemical Reactions

• A chemical reaction is a process that involves the rearrangement of atoms and molecules to form new substances.
• Chemical equations represent chemical reactions, showing the reactants and products involved.
• Balancing chemical equations ensures that the number of atoms of each element is the same on both sides of the equation.
• Reaction types include synthesis, decomposition, single displacement, double displacement, and combustion reactions.
• Redox reactions involve the transfer of electrons between species.

Stoichiometry

• Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions.
• The mole is the SI unit for the amount of a substance, defined as the number of entities equal to the number of atoms in 12 grams of carbon-12.
• Molar mass is the mass in grams of one mole of a substance.
• Limiting reactant is the reactant that is completely consumed in a chemical reaction.
• Percent yield is the ratio of the actual yield to the theoretical yield, expressed as a percentage.

Acids and Bases

• Acids are substances that donate protons (H+) or accept electrons.
• Bases are substances that accept protons or donate electrons.
• pH is a measure of the acidity or basicity of a solution, with values ranging from 0 to 14.
• Acids have pH values less than 7, bases have pH values greater than 7, and neutral solutions have a pH of 7.
• Strong acids and bases completely dissociate in water, while weak acids and bases only partially dissociate.
• Buffers are solutions that resist changes in pH upon the addition of small amounts of acid or base.

Chemical Kinetics

• Chemical kinetics is the study of reaction rates and the factors that influence them.
• Reaction rate is the change in concentration of reactants or products per unit time.
• Factors affecting reaction rate include temperature, concentration, surface area, and catalysts.
• Catalysts speed up chemical reactions without being consumed in the process.
• The rate law expresses the relationship between reaction rate and the concentrations of reactants.

Chemical Equilibrium

• Chemical equilibrium is the state in which the rates of the forward and reverse reactions are equal, and the net change in concentrations of reactants and products is zero.
• The equilibrium constant (K) is a measure of the relative amounts of reactants and products at equilibrium.
• Le Chatelier's principle states that if a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress.

Thermodynamics

• Thermodynamics is the study of energy and its transformations.
• Energy is the capacity to do work or transfer heat.
• The first law of thermodynamics states that energy is conserved.
• Enthalpy (H) is a measure of the heat content of a system at constant pressure.
• Entropy (S) is a measure of the disorder or randomness of a system.
• Gibbs free energy (G) is a measure of the spontaneity of a process.

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds.
• Carbon can form stable bonds with itself and other elements, leading to a vast array of organic molecules.
• Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.
• Hydrocarbons are organic compounds containing only carbon and hydrogen.
• Alkanes, alkenes, and alkynes are types of hydrocarbons with single, double, and triple bonds, respectively.
• Isomers are molecules with the same molecular formula but different structural arrangements.

An overview of chemistry, the study of matter and its properties. Covers branches like analytical, organic, and biochemistry. Explores matter, elements, and the periodic table.