bonds and macromolecules Flashcards
element
a substance that cannot be broken down to there substances by chemical reactions
compound
a substance consisting of 2 or more elements in a fixed ratio
essential elements
oxygen > carbon > hydrogen > nitrogen
atomic number, mass number and atomic mass
atomic number: number of protons
mass number: protons + neutrons
atomic mass: atom’s total mass
isotopes
atomic forms of an element that differ in number of neutrons - radioactive decay spontaneously
outer most electron shell =
valence electrons
- determines chemical behavior
- unreactive when complete
covalent bond
sharing of a pair of valence electrons by 2 atoms
- molecule
non polar and polar
non polar: electrons share equally
polar: one atom is more electronegative than the other
- partial pos and neg
ions
after a transfer of electrons, both atoms have charges called
weak chemical bonds
ionic, hydrogen and Van der Waals
hydrogen bond
forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom
Van der Waals interactions
occur when atoms and molecules are close together, strong when collective - geckskin
molecule shape
key to its function - structure determines function
water
- molecules polar
four properties - cohesive behavior
- ability to moderate temp
- expansion upon freezing
- versatility as a solvent
why does Ice float?
solid water has hydrogen bonds that are more stable, liquid water has bonds that break and reform
four ways carbon skeletons vary
length, double bond position, branding and presence of rings