Chemical Bond                                                electrons and protons, the atom is called
                                                             an Ion.
   It is the attraction between two atoms or               If the atom has more electrons than
    ions that holds them together.                           protons, it is a negative ion, or Anion. e.g.
   It is caused by the electrostatic force of               Hydroxide anion (OH-), Oxide anion (O2-)
    attraction between opposite charges, either             If it has more protons than electrons,it is a
    between electrons and nuclei, or as the                  positive ion, or Cation. e.g. Silver (Ag+),
    result of a dipole attraction.                           Hydronium (H3O+)
   Covalent or Ionic bonds are strong bonds                Ionic Compound is a compound
    and Dipole–Dipole bond and Hydrogen                      composed of cations and anions held
    bond are weak bonds.                                     together by electrostatic forces.
Valence                                                  Ionic Bond
   The valence or valency of an element is a               It formed by the electrostatic force of
    measure of its combining power with other                attraction between two oppositely charged
    atoms when it forms chemical compounds                   ions.
    or molecules.                                           It is formed due to transfer of electrons
   It is denoted using a positive or negative               from one atom to another.
    integer used to represent this binding                  Generally, it is formed between a metal
    capacity. It is also known as valency or                 atom and a nonmetal atom.
    valence number.                                         Its properties are Crystaline, stronger force
                                                             of attraction, thermally stable, low
Table of Element Valences
                                                             volatality, high density, high melting point
  No.     Element           Valence                          and boiling point.
  1       Hydrogen           (-1), +1                       e.g. NaCl, MgO2, CaCl2, etc.
  2       Helium             0
  3       Lithium            +1
  4       Beryllium          +2
  5       Boron              -3, +3
  6       Carbon             (+2), +4
  7       Nitrogen           -3, -2, -1, (+1), +2,       Covalent Bond
                            +3, +4, +5
  8       Oxygen             -2                             It formed between two atoms due to the
  9       Fluorine           -1, (+1)                        sharing of electron pairs.
  10      Neon               0                              Generally, it formed by two nonmetal
                                                            Its properties are low melting point and
Ions                                                         boiling point, non-conductor, and soluble
                                                             in non-polar solvent, rigid and directional
   It is a charged atom or molecule. It is
    charged because the number of electrons
                                                            e.g. H2, Cl2, HCl, etc.
    do not equal the number of protons in the
    atom or molecule.
   An atom can acquire a positive charge or a
    negative charge depending on whether the
    number of electrons in an atom is greater
    or less then the number of protons in the            Coordinate Covalent Bond
   When an atom is attracted to another atom               It is formed when one atom donates both
    because it has an unequal number of                      of the electrons to form a single covalent
                                                             bond. These electrons originate from the
                                                             donor atom as an unshared pair.