Chemistry 2.0

• Pure substance


  Made up of only one type of particle, either an element or a compound
• Impure substance


  Contains more than one type of particle
• Boiling and melting points


  • Can be used as criteria for purity because pure substances have specific and consistent boiling and melting points, while impure substances may have a range of temperatures at which they boil or melt
• Types of substances


  • Elements
  • Compounds
  • Mixtures
• Elements


  Substances that cannot be broken down into simpler substances by chemical means
• Compounds


  Substances made up of two or more different elements chemically combined
• Mixtures


  Combinations of two or more substances that are physically mixed together but not chemically combined
• Chemical changes


  Involve the formation of new substances with different properties
• Physical changes


  Only affect the physical properties of a substance without changing its chemical composition
• Properties of components in a mixture

  • Can vary depending on the specific mixture, including differences in color, density, solubility, boiling point, and more
• Separation methods


  • Distillation (based on differences in boiling points)
  • Filtration (based on differences in particle size)
• Everyday applications of separation processes

  • Filtering coffee grounds from coffee
  • Separating different components in recycling
  • Purifying water through distillation
• Performing simple calculations involving formulae, equations/chemical composition, and the mole concept


  1. Using mathematical formulas

  2. Understanding the relationships between different substances in a chemical reaction

  3. Keeping track of the number of atoms or molecules involved

  4. Using the concept of moles to convert between mass, number of particles, and volume
• Deducing chemical laws from given expressions/statements/data

  1. Analyzing the provided information

  2. Identifying patterns or relationships

  3. Understanding the principles behind chemical reactions and the behavior of substances
• Interpreting graphical representations related to these laws

  1. Analyzing graphs that show the relationship between different variables

  2. Examining the shape and trends of the graph

  3. Drawing conclusions about the behavior of substances and the laws that govern them
• Deducing the stoichiometry of chemical reactions

  1. Determining the balanced chemical equation

  2. Understanding the mole ratios between the reactants and products

  3. Using stoichiometric calculations to determine the amount of reactants needed or the amount of products produced
• Solids, liquids, and gases

  • Solids have a fixed shape and volume
  • Liquids have a fixed volume but can change shape
  • Gases have neither a fixed shape nor volume
• Changes of state


  Caused by changes in temperature and pressure
• Molecular motion


  • In solids, particles vibrate in fixed positions
  • In liquids, particles move more freely but still remain close together
  • In gases, particles move rapidly and have more space between them
• Gas laws


  • Boyle's law
  • Charles's law
  • Combined gas law
• Interpreting graphical representations related to gas laws

  1. Analyzing graphs that show the relationship between variables like pressure, volume, and temperature

  2. Examining the shape and trends of the graph
• Performing simple calculations based on gas laws, equations, and relationships


  Using mathematical formulas to solve for unknown variables
• Building blocks of matter

  • Atoms
  • Molecules
  • Ions
• Democritus proposed the concept of atoms
• Dalton developed the atomic theory
• Thomson discovered the electron
• Rutherford discovered the nucleus
• Bohr proposed the planetary model of the atom
• Deducing the number of protons, neutrons, and electrons from atomic and mass numbers


  1. Using the periodic table

  2. Atomic number represents the number of protons and electrons

  3. Mass number represents the sum of protons and neutrons

  4. Subtracting the atomic number from the mass number gives the number of neutrons
• Arrangement of electrons in an atom

  • Follows the Aufbau principle, Pauli exclusion principle, and Hund's rule
• Isotopes


  Variants of an element with the same number of protons but different numbers of neutrons
• Isotopy and mass number


  Isotopes have different mass numbers due to varying numbers of neutrons
• Performing simple calculations relating to isotopy

  Determining the average atomic mass of an element based on the relative abundance of its isotopes
• Shapes of atomic orbitals


  • s orbital is spherical, p orbitals have dumbbell shapes along different axes
• Number of electrons in s and p orbitals

  s orbital can hold a maximum of 2 electrons, p orbitals can hold a maximum of 6 electrons (2 in each of the three p orbitals)
• Atomic number and position on the periodic table

  Atomic number represents the number of protons, elements are arranged in order of increasing atomic number
• Properties of groups on the periodic table

  • Elements in the same group share similar chemical properties, such as valence, electron configuration and reactivity
• Variation in properties across periods and down groups

  Caused by changes in atomic structure and electron configuration
• Types of chemical bonding

  • Ionic
  • Covalent
  • Metallic
• Deducing bond types based on electron configurations


  Considering the electronegativity difference between atoms