LESSON 1

• ATOMOS (400 BC) Democritus - Atoms are the building blocks of matter, the shape of an atom explain elements behavior.
• John Dalton SOLID SPHERE (1803)- Atom is a solid indivisible sphere.
• J.J Thomson PLUM PUDDING (1897) - Negative electrons are embedded in a sea of positive charges.
• Ernest Rutherford NUCLEAR (1911) - Positive charges are located within a central nucleus.
• Niels Bohr PLANETARY (1913) - Electrons are restricted in circular orbits

  with different energy levels.
• Erwin Schrödinger QUANTUM (1926) - Electrons are in clouds surrounding the nucleus, and this cloud is less dense.
• ATOMIC ORBITALS - Electrons act like waves.
• ATOMIC ORBITALS - The exact location of electrons cannot be

  determined.
• ORBITALS - A region in an atom where there is a high probability of finding electrons
• ORBITALS - Atomic orbitals (s, p, d, or f)
• PRINCIPAL - Distance of the electron from nucleus
• AZIMUTHAL - Shape of the orbital.
• MAGNETIC - Orientation of the orbital.
• SPIN - Orientation of the electron spin.
• ELECTRON CONFIGURATION NOTATION - The electron configuration of an element describes how electrons are distributed in its atomic orbitals.
• STABILITY OF NOBLE GASES - Elements in Group 8A also called as noble gases are the most stable elements in the periodic table and are thus nonreactive under ordinary conditions; hence, the description “inert”.
• STABILITY OF NOBLE GASES - Except for helium with only two

  electrons in its orbital, noble gases--- with a general valence

  configuration of ns 2N2 --- have 8 valence electrons. Such octet

  configuration is the most stable arrangement an atom can have.
• STABILITY OF NOBLE GASES - The atoms of the other elements in the periodic table tend to achieve the configuration of the nearest noble gas by reacting with the same element or with other elements to form new compounds.
• STABILITY OF NOBLE GASES - This principle is referred to as the octet rule.
• LEWIS STRUCTURE OF REPRESENTATIVE ELEMENTS

  In 1916 American chemist Gilbert Lewis (1875 – 1946) developed a system of Representing the valence electrons of atoms using diagrams called Lewis electron–dot structures or Lewis structures.
• LEWIS STRUCTURE OF REPRESENTATIVE ELEMENTS

  A Lewis structure consists of a symbol of an element surrounded by one or more dots: each dot corresponds to a valence electron in an atom of an element. Only two dots are placed in each of the four sides.
• WRITING LEWIS STRUCTURE


  A dot is placed in each of the four sides of the element symbol before pairing with another as needed to represent all the valence electrons of the elements.
• WRITING LEWIS STRUCTURE - pair up first so the dot symbol for oxygen

  may be written in several equivalent forms. There are no strict rules on which sides to
• IONS AND THEIR LEWIS STRUCTURE - Metals have one to three valence

  electrons, which can be easily removed because of their relatively low ionization energy.
• IONS AND THEIR LEWIS STRUCTURE - Nonmetals having high electron affinity, can gain valence electrons to fill their sand p orbitals and form an octet.
• LEWIS STRUCTURE OF IONS

  
• FORMATION OF IONIC COMPOUNDS - Electrons given off by a metal atom are gained by the nonmetal, forming ionic bond in the process.
• IONIC COMPOUNDS AND LEWIS STRUCTURE - Ionic compounds generally exist between a metal and a nonmetal as a result of their

  high electronegativity difference.
• PROPERTIES OF IONIC COMPOUND

  HIGH MELTING POINT AND BOILING POINT - The ionic bonds that bind the ions are strong such that high energy is required to separate the ions and allow them to move freely and form a liquid and gas.
• PROPERTIES OF IONIC COMPOUND

  CONDUCTS ELECTRICITY - Solid ionic compounds generally do not conduct electricity because their constituent particles are bound by strong ionic bond in a lattice. But when in a solution, the particles are dissociated and can move easily. This movement of ions allows the solution to conduct electricity.
• SOLID AT A ROOM TEMPERATURE - Ionic compound assumes a solid lattice where the cations and anions are arranged in an alternating sequence, making the

  structure stable.
• HARD AND BRITTLE - Ionic compounds are generally hard because of their fixed and stable lattice. Most ionic compounds are also brittle. An external force applied to the crystal ma distort its lattice, make like charges align,

  and then repel, causing the crystal to break.