CHEM 3RD Q

• ATOMOS (400 BC) Democritus


  ★ Atoms are the building blocks of matter, the shape of an atom explain elements behavior.
• SOLID SPHERE (1803) John Dalton


  ★ Atom is a solid indivisible sphere.
• PLUM PUDDING (1897) J.J Thomson


  ★ Negative electrons are embedded in a sea of positive charges
• NUCLEAR (1911) Ernest Rutherford


  ★ Positive charges are located within a

  central nucleus.
• PLANETARY (1913) Niels Bohr


  Electrons are restricted in circular orbits with different energy level
• QUANTUM (1926) Erwin Schrödinger


  Electrons are in clouds surrounding the nucleus, and this cloud is less dense.
• ATOMIC ORBITALS


  ★ Electrons act like waves.

  ★ The exact location of electrons cannot be determined.
• ORBITALS 


  ★ A region in an atom where there is a high probability of finding electrons

  ★ 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

  describes how electrons are distributed in its atomic orbitals
• 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.
• ★ Elements in Group 8A also called as noble gases
• Nonmetals


  ★ having high electron affinity, can gain valence electrons to fill their s and p orbitals and form an octet.
• Two Electron Domains

  – separated by 180 Degrees
• Three Electron Domains

  separated by 120 Degrees.
• Four Electron Domains

  separated by 109.5 Degrees.
• Trigonal Bipyramidal

  
• Seesaw

  
• T-Shaped

  
• Linear

  
• Octahedral

  
• Square Pyramidal

  
• Square Planar

  
• Non Polar


  0.00-<0.40
• LINUS PAULING 


  ★ Pauling scale of electronegativity
• Polar


  >0.41-<1.7
• Ionic


  >1.71
• POLARITY OF MOLECULES


  A polar molecule always contains one or more polar bonds; but some molecules with polar bonds can be nonpolar overall.
• NONPOLAR COVALENT


  Bonding electrons shared equally between two atoms. No charges on atoms.
• POLAR COVALENT BOND


  ★ Bonding electrons shared unequally between two atoms. Partial charges on atoms.
• Intramolecular Force


  type of force that are relatively strong because their charges are larger and closer
• INTERMOLECULAR FORCES


  The attractive forces between particles.
• JOHANNES DIEDERIK VAN DER WAAL


  Dutch Physicist, winner of the 1910 Nobel Prize for Physics for his research on the gaseous and liquid states of matter. ★ Van der Waals force, named after him ★ A force of attraction between two nonpolar substances. Molecules can attract each other at moderate distances and repel each other at close range.
• DIPOLE - DIPOLE FORCES


  It exists between polar molecules. Polar molecules possess a permanent dipole moment. It is attributed to the electronegativity difference.
• DIPOLE - INDUCED DIPOLE FORCES


  It is an interaction between nonpolar and polar molecules
• HYDROGEN BONDS


  It is a special type of dipole - dipole interaction that only exists in molecules containing a hydrogen atom
• Hydrogen Bonds