Chem

• Atom is a the smallest unit of an element and the building blocks of everything
• Molecule is two or more atoms bonded together
• Compound is molecules made up of different elements that are chemically combined
• Covalent Bonds occur between non-metals where they share pairs of electrons
• Ionic Bonding occurs when one atom loses electrons to another atom, creating positive and negative charges.
• Metals have high melting points because they have strong metallic bonds which require lots of energy to break them apart.
• Covalent Bonds are formed by sharing pairs of electrons between non-metal atoms.
• Ionic bonds occur when metals lose their outer shell electron to become positively charged, while non-metals gain these electrons to form negatively charged ions.
• Metallic Bonding occurs when metal atoms give away some of their valence electrons to other metal atoms so all the atoms have full outer shells
• Hydrogen bonding occurs when hydrogen atom shares its single pair of electrons with another atom (usually oxygen)
• Non metals have low melting points as their covalent bonds can be broken easily with little energy required.
• Non-polar covalent bonds form when the shared pair of electrons is equally distributed between both atoms.
• In covalent compounds, there is no transfer of electrons but instead, two or more atoms share electrons.
• Polar Covalent Bonds form when there is an unequal distribution of electron density around the nucleus due to differences in electronegativity.
• Nucleus is the center of atom

  Electron Cloud is the region that surrounds the nucleus

  Subatomic Particles: Electron, Neutron, Proton

  Electron is the lighest

  Proton located inside the nucleus

  The mass number is the atomic mass
• Atomic Number = # protons + # neutrons
• Mass Number = # protons + # neutrons
• Electrons


  Negatively-charged particles found outside the nucleus
• Protons


  Positively-charged particles found inside the nucleus
• Neutrons


  Electrically neutral particles located in the nucleus of the atom
• Ionization


  The process in which an atom loses, or gains electrons
• Ion


  An atom that has lost or gained one or more electrons, acquiring a net electrical charge
• Cation


  A positive ion
• Anion


  A negative ion
• Isotopes


  • Atoms of the same element with different mass numbers
• Ionic Bonds


  • Has transfer of electrons
  • Opposite charges attract each other
  • Usually Metals and Non-metals
• Covalent Bonds


  Sharing of electrons
• Types of Covalent Bonds

  • Non-Polar - electrons are shared equally
  • Polar - electrons are shared unequally
• Elements

  • Hydrogen (H)
  • Helium (He)
  • Lithium (Li)
  • Carbon (C)
  • Nitrogen (N)
  • Oxygen (O)
  • Fluorine (F)
  • Neon (Ne)
  • Sodium (Na)
  • Magnesium (Mg)
  • Aluminum (Al)
  • Silicon (Si)
  • Phosphorus (P)
  • Sulfur (S)
  • Chlorine (Cl)
  • Potassium (K)
  • Calcium (Ca)
  • Chromium (Cr)
  • Iron (Fe)
  • Nickel (Ni)
  • Copper (Cu)
  • Zinc (Zn)
  • Bromine (Br)
  • Silver (Ag)
  • Gold (Au)
  • Mercury (Hg)
  • Iodine (I)
  • Lead (Pb)
  • Tin (Sn)
  • Cobalt (Co)
• Atomos


  Small, finite particles that all matter is composed of, derived from the Greek word for "uncuttable"
• Rutherford's Gold Foil Experiment showed that atoms have a small, dense, positively charged nucleus surrounded by a large empty space with negatively charged electrons orbiting it
• Democritus


  Stated the invisible particles
• John Dalton


  Stated that atoms cannot be created nor destroyed, compounds
• John Joseph Thomson


  Plum pudding model
• Rutherford

  Discovered protons and nucleus
• Nheils Bohr

  Thought that electrons were moving in orbits around the nucleus