Lesson 4 | Polarity of Molecules

    Cards (18)

    • Element is a pure substance made of all same atoms
    • Compound - two or more elements bonded together
    • group of atoms (2 or more atoms bonded together)
    • not all molecules are compounds, but all compound are molecules
    • CHEMICAL BONDING- attraction between atoms, ions or molecules that enables the formation of chemical compounds
    • IONIC BOND – transfer of one or more valence electron (outer shell electron associated with an atom and that participates in the bonding process) from one atom to another ---- metal + non-metal
    • COVALENT BOND – sharing an electron pair between atoms --- non-metal + non-metal
    • Polar covalent – electrons are unequally shared, unbalanced distribution of electrical charge
    • Non-polar covalent – equal sharing, balanced electron charge
    • POLARITY means having dipoles or a positive and negative ends
    • dipole has 2 partially-charged regions / poles of a molecule and is symbolized by an arrowhead pointing to the more electronegative atom and a cross tail located at a less electronegative atom.
    • POLAR COVALENT
      ▹ Have DIPOLES
      ▹ Polar bonds present and arranged in such a way that the bond dipoles do not cancel
      ▹ The charge is not uniformly distributed (electrically asymmetric)
      ▹ Have lone pairs (pair of valence electrons that do not participate in bonding) at the central atom
    • NON-POLAR COVALENT
      ▹ Do not have dipoles because they add up to zero or cancel out
      ▹ The charge is uniformly distributed (electrically symmetric)
      ▹ No lone pairs on central atom
    • OCTET RULEattraction between atoms, ions or molecules that enables the formation of chemical compounds . An element should have contact to eight valence electrons in a bond or exactly fill up its valence shell, to ensure that the atom is stable.
    • ELECTRONEGATIVITY DIFFERENCE (EN)
      -the degree to which an atom attracts electrons in a chemical bond
      Elements with the higher EN value become thepartial negative pole while elements with thelower EN value become the partial positive pole. This makes the molecule a polar molecule.
    • ELECTRONEGATIVITY– tendency of an element to
      attract an electron from other atoms.
    • MOLECULAR GEOMETRY
      -The valence shell electron pair repulsion theory or VSEPR theory helps predict the spatial arrangement of atoms in a polyatomic molecule.
    • LEWIS DOT STRUCTURE - simplified representation of the valence shell electrons in a molecule. It is used to show how the electrons are arranged around individual atoms in a molecule. Electrons are shown as "dots" or for bonding electrons as a line between the two atoms.
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