Unit 3 - Chemistry

  • Sub-Atomic Particles
    • One Atom Consists on Protons, Neutrons, and Electrons

      		• Mass
        		Charge
        Proton
        		1.673 x 10-27 kg
        		+1
        Neutron
        		1.675 x 10-27 kg0
        Electron
        		9.109 x 10-31 kg-1
      • Atoms with an unequal amount of protons and neutrons are called Isotopes (p 206)
      • Atoms with an unequal amount of protons and electrons are called Ions (p 253)
        • Cations - Positive Ions - get by Losing Electrons
        • Anions - Negative Ions - get by Gaining Electrons

  • Theories of the Atom
    • Rutherford, Bohr and electron cloud theories
      • Rutherford Model (p211 - p213) - A model that said the atom is made of a dense, positively-charge nucleus with electrons orbiting the nucleus in circles; Planetary Model
      • Bohr Model (p224-229) -  a model similar to the Rutherford model; Suggested that not only did electrons revolve around the nucleus in a particular orbit, but could jump from one obit to another
        • When an electron jumps from one orbit to another it is said to be excited
        • All matter tries to stay in its lowest possible energy state
        • The ground state is the lowest possible energy state for a given substance

    • Electron Configuration (p 234)
      • Element Electron configuration
        Scandium 1s2 2s2 2p6 3s2 3p6 4s2 3d1
        Titanium 1s2 2s2 2p6 3s2 3p6 4s2 3d2
        Vanadium 1s2 2s2 2p6 3s2 3p6 4s2 3d3
        Chromium 1s2 2s2 2p6 3s2 3p6 4s1 3d5

      • "...one way you can abbreviate electron configurations is to look for the nearest atom in 8A that has a lower atomic number than the atom you are interested in." - (p 237)
      • Element Abbriviated electron conf.
        Scandium [Ar] 4s2 3d1
        Titanium [Ar] 4s2 3d2
        Vanadium [Ar] 4s2 3d3
        Chromium [Ar] 4s1 3d5

    • Valence Electrons
      • "Valence Electrons are the electrons that exist farthest from an atom's nucleus. They are generally the electrons with the highest energy level number" - p248
      • Octet Rule - Most atoms strive to attain eight valence electrons
      • "A Lews Structure consists of an atom's symbol surronded by dots. Each dot represents a valence electron of the atom" - (p250)