AP Bio Chapter 2

Element

Substance that cannot be broken down to other substances by chemical reactions

Compound

A substance consisting of two or more different elements combined in a fixed ratio

Essential element

20-25%, needed for organisms to live a healthy life and reproduce

Trace elements

required in only minute amounts

The partial charge of the O atom in water

negative

The partial charge of the H atoms in water

negative

heat

Transfer of thermal energy from one body to another

Kinetic Energy

The energy of motion. Anything that moves

Temperature

average kinetic energy of the molecules in a body of matter, regardless of volume

Thermal Energy

Total kinetic energy and depends on the matter’s volume

Atomic number

Amount of protons

Mass number

amount of protons and nuetrons

Isotope

atoms with more neutrons than other atoms of the same element. More mass

Radioactive Isotope

Nucleus decays spontaneously, giving of particles and energy

Energy

Capacity to cause change

Potential enery

Energy that matter posses because of its location or structure

Covalent bonds

Sharing of a pair of valence electrons by two atoms

Electronegativity

Attraction of a particular atom for the electrons of a covalent bond. More E.N, stronger pull on shared electrons

Non-polar covalent bonds: Electrons have the same electronegativity

van der Waals interactions

changing regions of positive and negative charge that enable all atoms and molecules to stick to one another. Weak and occur only when atoms and molecules are very close

Cohesion

Hydrogen bonds hold the substance together. Attraction between SAME substance.

Adhesion

Clinging of one substance to another between DIFFERENT substances

Surface tension

Measures how difficult it is to break or stretch the surface of a liquid

Specific heat

The amount of heat that must be absorbed for 1g of the substance to increase temperature by 1 degree celcius.

Heat of vaporization

Quantity of heat a liquid must absorb for 1 g of it to be converted from liquid to gass

Hydrogen shell

The sphere of water molecules around each dissolved ion

Hydronium ion

Proton binds to the other water molecule to become H3O

Acid

Increases the hydrogen ion concentration

Base

Reduces hydrogen ion concentration

Buffer

minimizes changes in concentration of H and OH

Ocean acidification

CO2 dissolves in seawater and reacts with water to form carbonic acid

Formula for pH

-log[H+]