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    Atomicsstructure Atomicsstructure Presentation Transcript

    • Introduction to Atomic Structure
    • ATOMS
      • Considered the building blocks of matter
      • Made up of three main subatomic particles:
        • Protons
        • Neutrons
        • Electrons
      • All protons are identical, regardless of the element in which they are found. This is also true for neutrons and electrons.
    • Nucleus
      • Atoms have a small, dense nucleus in the middle but most of the atom is nothing more than empty space!
      • Extremely small in size relative to the atom but it contains 99.99% of the atom’s mass.
        • If the atom were enlarged to the size of a football stadium, the nucleus would be the size of a bee!
      • Contains 2 of the 3 subatomic particles
        • Protons (+ charged particles)
        • Neutrons (neutrally charged particles)
    • Atomic Mass Units
      • Mass of proton = 1 amu (atomic mass unit)
      • 6 23 amu = 1 gram
      • Neutrons have slightly more mass than protons but they are considered equal.
      • Mass of neutron still = 1 a.m.u.
      • Mass of electron is tiny even on an atomic scale (0.0006 amu).
    • Atomic #
      • # of protons in nucleus determines the atomic number of an element.
      • This identifies the element!
      • Hydrogen--Atomic #1 = 1 proton
      • Helium--Atomic #2 = 2 protons
      • Oxygen--Atomic # 8 = 8 protons
        • All atoms with 8 protons MUST be oxygen!
        • The # of protons in an atom CANNOT be changed (otherwise, you will have a different element!)
    • Isotopes
      • Even though the # of protons will never change, the # of neutrons can vary from atom to atom.
      • Atoms of the same element that have the same # of protons, but different number of neutrons are called isotopes .
      • Every single atom is going to be an isotope of that element!
    • Isotopes
      • Hydrogren has 3 different isotopes (all of them have 1 proton)
        • Protium (no neutrons)
        • Deuterium (1 neutron)
        • Tritiuim (2 neutrons)
      • Every atom of “H” is going to be one of these isotopes!
    • Mass number
      • Mass # of an atom is the sum of the protons and neutrons in its nucleus.
      • The electrons are ignored because they are so small!
      • The mass number varies for different isotopes of an element.
    • Mass number
      • Carbon has two known isotopes:
        • Carbon-12 (6 protons and 6 neutrons) (6 electrons)
        • Carbon-14 (6 protons and 8 neutrons) (6 electrons)
    • Atomic Mass
      • Any sample of an element as it occurs in nature contains a mixture of isotopes.
      • The atomic mass of an element is the average mass of all the isotopes of that element. Therefore, the atomic mass is usually not a whole number.
    • Atomic Mass
      • For example, the atomic mass for carbon is 12.011
      • Remember, there are two naturally-occurring isotopes: C-12 and C-14
      • Since the atomic mass is much closer to “12”, this tells you that there are MANY more atoms of Carbon-12 than there are Carbon-14.
    • Electrons
      • Electrons have a negative charge and are found outside of the nucleus.
      • In an uncharged atom, the # of electrons = # of protons
      • Always assume that the atom has a zero charge and is neutral.
    • Ions
      • Sometimes, atoms will either lose or gain electrons.
      • When this happens, they do not equal the # of protons, and the atom becomes positively or negatively “charged”.
      • These charged atoms are called ions .
    • Electron Cloud
      • Space in which electrons are found.
      • Arranged in energy levels:
      • Lower energy level = closer to the nucleus
      • Higher energy level = further from nucleus
        • 1 st energy level - 2 electrons.
        • 2 nd energy level -8 electrons
        • 3 rd energy level -18 electrons
    • Electron Cloud
      • An atom’s bonding ability is determined by the arrangement of electrons in the outermost energy level.
      • These are called valence electrons.
      • Atoms that have only one electron or those that only need one electron are much more likely to bond.
      • Some elements have a complete set of electrons and will not bond (Noble Gases)
    • Quarks
      • It is possible to get even smaller than these three subatomic particles.
      • Current theory states that protons and neutrons are themselves made up of even smaller particles known as quarks.
      • There better our technology gets, the more subatomic particles there are being discovered.