Chemistry definitions

• Element


  Cannot be broken down to other substances via chemical reactions
• Atom


  Smallest unit of matter with properties of an element
• Atomic number


  Number of Protons
• Atomic mass


  Number of Protons and Neutrons
• Isotopes


  • Same atomic number, different mass number
  • Chemically identical
• Compound


  Two or more elements in a fixed ratio
• Covalent Bonds


  Sharing of electrons by two atoms
• Hydrogen bonds

  Between polar molecules
• Ionic bonds


  • Sharing of electrons between 2 atoms with different attractions
  • Crystal lattice
• Van der Waal's forces


  Very weak interaction between electron clouds
• Atomic orbitals

  Orbitals contain 2 electrons