Introduction to Chemistry

The provided text is identical to the existing notes, so no updates are necessary. Chemistry is defined as the study of matter, its properties, and how it changes.

Branches of Chemistry

• Analytical Chemistry focuses on the composition of matter.
• Biochemistry studies chemical processes related to living organisms.
• Inorganic Chemistry studies substances lacking carbon.
• Organic Chemistry studies carbon-containing compounds.
• Physical Chemistry deals with the physics behind chemical systems.

States of Matter

• Solids have definite shape and volume.
• Liquids have definite volume, taking the shape of their container.
• Gases lack definite shape or volume.
• Plasma is ionized gas at high temperatures.
• Changes in state are physical.

Chemical and Physical Properties

• Physical properties are observable without changing composition, such as color and density.
• Chemical properties describe reactions and compositional changes, like flammability.

Elements and Compounds

• Elements are pure substances that cannot be broken down chemically, like gold.
• Compounds are substances of two or more elements in a fixed ratio, like water.

Mixtures

• Mixtures combine two or more physically combined substances, such as air.
• Homogeneous mixtures have uniform composition, like saltwater.
• Heterogeneous mixtures have non-uniform composition, like salad.
• Mixtures are separated by physical means like filtration.

Atoms

• Atoms are the basic building blocks of matter, consisting of protons, neutrons, and electrons.
• Protons are positive and located in the nucleus.
• Neutrons are neutral and located in the nucleus.
• Electrons are negative and orbit the nucleus.
• The number of protons determines the element.
• Isotopes are atoms of the same element differing in neutron number.

Molecules and Ions

• Molecules have two or more atoms held by chemical bonds, like O2.
• Ions are atoms or molecules with an electrical charge from gained or lost electrons.
• Cations are positive ions formed by losing electrons.
• Anions are negative ions formed by gaining electrons.

Chemical Bonds

• Ionic bonds involve electron transfer between atoms.
• Covalent bonds involve electron sharing between atoms.
• Metallic bonds, found in metals, feature delocalized electrons.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms and molecules.
• Reactants undergo change, and products are formed as a result.
• Chemical equations use symbols and formulas to represent chemical reactions.
• Balanced chemical equations have equal atom numbers for each element on both sides.

The Mole

• The mole is the SI unit for substance amount.
• One mole contains Avogadro's number (6.022 x 10^23) of particles.
• Molar mass is the mass of one mole, in grams per mole.

Stoichiometry

• Stoichiometry studies quantitative relationships in chemical reactions.
• Balanced equations determine mole ratios between reactants and products.
• The limiting reactant is fully consumed, determining the maximum product formed.
• Percent yield is the ratio of actual yield to theoretical yield, expressed as a percentage.

Acids and Bases

• Acids donate protons (H+) or accept electrons.
• Bases accept protons (H+) or donate electrons.
• The pH scale measures acidity or basicity: below 7 is acidic, above 7 is basic, and 7 is neutral.
• Strong acids and bases fully dissociate in water.
• Weak acids and bases partially dissociate in water.

Chemical Equilibrium

• Chemical equilibrium occurs when forward and reverse reaction rates are equal.
• Reactant and product concentrations remain constant at equilibrium.
• Le Chatelier's principle states that a system at equilibrium shifts to relieve stress from changing conditions.

Thermodynamics

• Thermodynamics studies energy and its transformations.
• Energy can be heat or work.
• The first law of thermodynamics says that energy is conserved.
• Enthalpy (H) measures the heat content of a system.
• Entropy (S) measures the disorder of a system.
• Gibbs free energy (G) measures reaction spontaneity.

Reaction Rates and Kinetics

• Kinetics studies reaction rates.
• Reaction rate is the speed at which reactants convert to products.
• Factors affecting reaction rate include concentration, temperature, surface area, and catalysts.
• Catalysts accelerate reactions without being consumed.

Oxidation-Reduction Reactions

• Redox reactions involve electron transfer.
• Oxidation is the loss of electrons.
• Reduction is the gain of electrons.
• Oxidizing agents accept electrons and get reduced.
• Reducing agents donate electrons and get oxidized.

Organic Chemistry

• Organic chemistry studies carbon-containing compounds.
• Carbon atoms can form chains and rings.
• Functional groups dictate chemical reactions within molecules.
• Hydrocarbons contain only carbon and hydrogen.
• Isomers share a molecular formula, but have different structures.

Nuclear Chemistry

• Nuclear chemistry involves reactions of atomic nuclei.
• Radioactivity is the emission of particles or energy from unstable nuclei.
• Alpha particles, beta particles, and gamma rays are common radiation types.
• Nuclear fission splits a heavy nucleus into lighter nuclei.
• Nuclear fusion combines light nuclei into a heavier nucleus.
• Half-life is the decay time for half of radioactive atoms in a sample.