General Chemistry

• Chemistry is the study of matter, which includes anything that occupies space and has mass
• Matter is composed predominantly of atoms, molecules, and ions, and is interconvertible with energy
• Mass refers to the amount of matter present in a material, while weight is mass multiplied by the pull of gravity
• Properties of matter can be intensive/intrinsic (mass independent) or extensive/extrinsic (mass dependent)
• Intensive properties are characteristics of a substance regardless of the sample's shape or size, like density, melting point, pH, color, and boiling point
• Extensive properties depend on the amount of substance present, such as volume, weight, pressure, and heat content
• Changes that matter undergoes can be physical (change in phase) or chemical (intrinsic and extrinsic properties change)
• Evidences of a chemical change include the evolution of gas, formation of a precipitate, emission of light, and absorption/liberation of heat
• The physical states or phases of matter are solid, liquid, gas, and plasma, with plasma having solid-like properties
• Matter can be classified as pure (elements and compounds) or impure/mixture (homogeneous and heterogeneous)
• Elements are the simplest form of matter, composed of one kind of material or atom, with a definite chemical composition
• Compounds are substances composed of two or more elements united chemically in definite proportions
• Mixtures can be heterogeneous (two or more distinct phases) or homogeneous (only one phase), like solutions, suspensions, and colloids
• Colloids contain particles bigger than those in solutions but smaller than those in suspensions, exhibiting properties like the Tyndall Effect and Brownian Movement
• Laws of chemical changes include the Law of Conservation of Mass, stating that mass is neither created nor destroyed in any transformation of matter
• Changes of state include melting, solidification, freezing, boiling, evaporation, liquefaction, condensation, sublimation, and deposition
• Processes of separating components of mixtures include decantation, distillation, magnetic separation, sorting, filtration, and chromatography
• Processes involved in chemical changes are combustion, reduction, neutralization, hydrolysis, saponification, and fermentation
• Nuclear changes involve alterations in the structure and properties of the nucleus of an atom, leading to the transmutation of elements
• Nuclear Change results in a change in the structure and properties of the nucleus of an atom, leading to the transmutation of the element into another element
• Nuclear Fission is the splitting of a heavy atom
• Nuclear Fusion is the union of 2 light atoms to form a bigger molecule
• Types of Chemical Reactions:

  • Direct Union/Synthesis/Composition involves the formation of elements
  • Combustion is a chemical combination with oxygen where metal oxides are basic and nonmetal oxides are acidic
  • Decomposition/Analysis is the breakdown of complex substances into simpler substances, with electrolysis causing a chemical change by passing electricity through a conducting solution
• Single Replacement reaction is represented as A + BC → B + AC, with examples like Na + HCl → H2 + NaCl
• Double Displacement/Metathesis reaction is represented as AB + CD → AD + CB, with an example like NaCl + AgNO3 → AgCl + NaNO3
• Neutralization is the reaction between an acid and a base to form salt and water
• Redox reactions involve oxidation and reduction processes, where oxidation involves the loss of electrons and reduction involves the gain of electrons
• Structure of Atoms:

  • Democritus proposed that matter is composed of tiny particles called Atomos
  • John Dalton introduced the Billiard Ball Model where an atom is a hard indestructible sphere, which was disproved with the discovery of subatomic particles like electrons, protons, and neutrons
• Thompson's model, the Raisin-bread Model, described an atom as a sphere of positive particles, while Rutherford's Gold Foil Experiment led to the Nuclear Model suggesting that atoms are mostly empty space with a concentrated nucleus containing protons and neutrons
• Bohr's Planetary Model stated that electrons move around in circular paths called orbitals with quantized energy levels, while Schrodinger's Quantum-Mechanical Model described electrons moving in a 3D space called electron cloud
• Ion is a charged atom, with the atomic number always equal to the number of protons and electrons, and the mass number being the sum of protons and neutrons
• Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, leading to different mass numbers
• Allotropism refers to atoms of different elements linking together in different ways to form substances with different properties
• Electrons are located in electron clouds or energy levels, with orbitals being regions in space where the probability of finding an electron is greatest
• Quantum Numbers:

  • Principal (n) describes the total energy of an electron and the size of the electron cloud
  • Angular Momentum/Azimuthal (l) defines the shape of the electron cloud
  • Magnetic (m) determines the orientation of the space of the electron cloud
  • Spin (s) indicates the direction of the spin or rotation
• Pauli's Exclusion Principle states that no two electrons can have the same set of quantum numbers, while Aufbau Principle dictates that lower energy levels are filled up first
• Hund's Rule of Maximum Multiplicity states that orbitals are filled up singly before pairing up, and the Heisenberg Uncertainty Principle states that it is impossible to determine simultaneously the momentum and position of an electron
• Hybridization of Orbitals includes Sp3 for hybrid orbitals, Sp2 for double bonds, and Sp for triple bonds
• Periodic Table history:

  • Antoine-Laurent Lavoisier is known as the Father of Modern Chemistry and created the first true periodic table based on classes like gases, metals, and minerals
  • Dobereiner proposed the Law of "TRIADS" based on physical and chemical properties of elements
  • Newlands introduced "octaves" based on sets of eight elements
  • Meyer and Mendeleev formulated the First Periodic Law stating that the physical and chemical properties are periodic functions of atomic weight
• The Aufbau principle states that electrons fill orbitals in the order of increasing energy levels, with elements grouped by the type of orbital being filled