enzymes

• AP Chemistry exam


  • 3-hour 15-minute, end-of-course test
  • 60 multiple-choice questions (1 hour 30 minutes, 50% of score)
  • 7 free-response questions (1 hour 45 minutes, 50% of score)
• Course content categories


  • Atomic Structure and Properties (7-9% of test questions)
  • Molecular and Ionic Compound Structure and Properties (7-9% of test questions)
  • Intermolecular Forces and Properties (18-22% of test questions)
  • Chemical Reactions (7-9% of test questions)
  • Kinetics (7-9% of test questions)
  • Thermodynamics (7-9% of test questions)
  • Equilibrium (7-9% of test questions)
  • Acids and Bases (11-15% of test questions)
  • Applications of Thermodynamics (7-9% of test questions)
• Matter


  Any substance that has mass and occupies space
• Atom


  Fundamental unit of matter, smallest unit that retains all the properties of an element
• Molecule


  Group of atoms that are bonded together to form a chemical compound
• Mole


  International standard unit of measure for the number of molecules in a substance, equal to Avogadro's number (6.022 x 10^23)
• Molar mass


  Total mass of one mole of a substance, expressed as grams/mole
• Determining number of molecules present

  1. Calculate number of moles using mass in grams and molar mass

  2. Multiply number of moles by Avogadro's number
• Mass spectroscopy


  Technique to measure the abundance of different atoms in a sample
• Mass spectrometer


  • Separates molecules in a sample based on their charge and weight
  • Bombards sample with electrons to charge it
  • Magnetic fields separate ions by charge
  • Detector reads relative abundance of ions

  
• Pure substance


  Made of a single type of substance with consistent characteristics, cannot be broken down further through physical processes
• Element


  Pure substance made of a single type of atom
• Compound


  Pure substance made of only one type of molecule
• Law of definite proportions: a pure chemical compound broken down into elements always contains elements of a fixed ratio, independent of where and how it was created
• Mixture


  Made of more than one type of element or compound, components can have different proportions
• Mixtures


  • No chemical reactions take place, components can be recovered in pure form
  • Can be homogenous (evenly distributed) or heterogenous (non-uniform distribution)
• Subatomic particles


  Protons (positively charged), electrons (negatively charged), neutrons (uncharged)
• Mass number


  Whole number equal to the number of protons and neutrons in an atom
• Atomic number


  Number of protons in the nucleus of an atom, defines the element

  
• Isotopes


  Atoms with the same number of protons but different number of neutrons
• Atomic mass


  Average mass number of all the atoms of an element
• Ion


  Atom with a non-zero charge, due to unequal number of electrons and protons
• Anion


  Negatively charged ion, formed by gaining electrons
• Cation


  Positively charged ion, formed by losing electrons
• Electron shells


  Discreet distances and energy levels where electrons occupy space outside the nucleus
• Subshells


  Within each shell, have slightly different energy levels
• Orbital


  Space within a subshell where an electron has the highest probability of being
• Calculating number of orbitals in a subshell

  2l + 1, where l is the subshell letter (s, p, d, f, etc.)
• Calculating number of electrons a shell can hold

  2n^2, where n is the shell number
• Aufbau principle


  Electrons fill the lowest energy orbitals first
• Hund's rule


  Electrons fill all orbitals of equal energy with one electron before pairing electrons
• Pauli exclusion principle


  Two electrons of the same spin cannot occupy the same orbital
• Paramagnetic


  Atoms with unpaired electrons that can interact with magnetic fields
• Diamagnetic


  Atoms with all subshells filled, do not interact with magnetic fields
• Valence shell


  The outer shell of an atom
• Covalent bond


  The sharing of electrons between a pair of atoms, also called a molecular bond. Covalent bonds can result in atoms having complete valence shells, stabilizing the atoms.
• Covalent bond


  • CO2
• Ionic bond


  The electrostatic attraction between cations and anions or with charged polyatomic ions. Ionic bonds involve the transfer of electrons from a metal to a non-metal, resulting in full valence shells for both atoms.
• Ionic bond


  • NaCl
• Metallic bond


  The sharing of free electrons in a metallic structure, composed of charged cations. Valence electrons are only loosely bound to the nucleus and form a sort of cloud around metallic cations, allowing them to be shared.