Molecules/Atoms Review

Elements in Human Body

N - nuetral : 1.7 x 10-24 grams = 1amu
E - Negative : 0amu
P - Positive : 1.7 x 10-24 grams = 1amu

Mass = P + N
Atomic = P in nucleus

Isotopes “2 atoms of an element that differ in nuetrons”
    Radioactive Isoptopes

• decay spontaneously

Radiometric Dating

• half-life - parent isotope decaying into daughter isotope at fixed rate , half life is the amount of time needed for one half of the parent to decay into daughter

Chem behavious in valence shells

• Atoms with incomplete valence shells share/transfer electrons or “Chemical Bonds”

  • Covalent bond - sharing between 2 atoms where the shared electrons count towards each part of the atoms valence shell

    • Non-polar ; electrons shared equally

    • Polar ; one atom is more electronegative

  • Ionic Bonds - atom taking electrons from other atom

    • “salts”

  • Hydrogen Bonds - basically hydrogen bonding between 2 diff molecules

• Chem reactions make and break chem bond

  • starting molecules = reactans

  • final molecules = products

• Most reactinos are reversible

  • products of the forward reaction becoms reactans for the reverse reaction

  • Chemical equilibrium is reached when the forward and reverse reactions occur at the same rate

    • At equilibrium, the concentrations or reactants/products dont change

Law of conservation of mass – no matter is created or destroyed in a chemical reaction, atoms are just rearranged.