Chapter 2: The Chemistry of Life Flashcards
Acid
any substance that dissociates in water to increase the [H+] (and lower the pH)
Adhesion
attraction of polar substances
Amphipathic molecules
contain hydrophobic and hydrophilic regions; associate into highly organized structures in water
Atom
smallest, stable components of cells; contain protons, neutrons, and electrons
Atomic mass
sum of masses of protons and neutrons in an action
Base
a substance that dissociates in water to decrease the [H+]
Bohr model
proton in middle with electrons on appropriate ring of energy level
Buffer
a substance that resists changes in pH
Chemical bond
atoms in a molecule are joined by this bond
Compound
when a molecule contains atoms of more than one element
Covalent bond
two atoms share one or more pairs of valence electrons
Cohesion
water molecules are attracted to one another
Dalton
unit of mass
Electron
negative charge
Electronegativity
atoms differ in their affinity for electrons
Element
substance consisting of one type of atom with the same number of protons
Energy level
electrons have energy of position. When an atom absorbs energy, an electron moves to a higher energy level, farther from the nucleus. When an electron falls to lower energy levels, closer to the nucleus, energy is released.
Evaporative cooling
ex.) sweat
Heat of vaporization
amount of energy required to change 1 gram of substance from liquid to gas