presentation: chapters 2 - ap biology with mrs. haas · presentation: chapters 2 chemical context...
TRANSCRIPT
Presentation: Chapters 2 Chemical Context of Life
Atom Basics
Atomic Structure
Atomic mass vs. Atomic Weight
Isotopes- Radioactive tracers
Intramolecular Forces
Bonding Forced WITHIN (Intra-) molecules
Covalent bonding- polar or non polar
Ionic bonding
Covalent Bonding
Sharing electrons
May be polar or non polar
Based on electronegativity= pull on electrons (affinity for e-)
Nonpolar= Atoms have equal electronegativity
Electrons are shared equally
ex. carbon and hydrogen, diatomic molecules
Polar= One atom has higher electronegativity
Electrons closer to one atom, partially negative
ex: oxygen and hydrogen
Examples
Polar Covalent Bond- Water
Oxygen has greater electronegativity
Electrons are drawn closer
Oxygen is now partially negative and hydrogens are partially positive
Polar Covalent Bonding
Non-polar Covalent Bonding
Ionic Bonding
Atoms gain (-) or lose (+) electrons to achieve a full outer (valence) shell
Oppositely charged ions (cation/anion) attract one another
A metal and a nonmetal
Usually forms a lattice pattern
Stronger than covalent bonding
Intermolecular Forces (IMFs)
Bonding BETWEEN (Inter-) molecules
Hydrogen Bonding
Dipole-dipole
Van der Waals forces
Hydrogen “Bond”/Interaction
Forms between two polar molecules
Hydrogen bonded to N, O, F the bonded to another polar molecule
Partial charges of one molecule are attracted to the opposite charges of another
Ex. water and ammonia
Other IMFs
Van der Waals attractions
Weak IMFs caused by changing dipoles
Gecko Fingers