The most abundant elements in living things are: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur.

Matter is made up of elements

Elements are made up of atoms

Atoms are made up of 3 subatomic particles: Protons, Neutrons, Electrons.

Each element has a unique number of protons.

An Isotope is a same type of element that differs in the number of neutrons

An Ion is a charged atom that adds or loses electrons

Mass number: # of protons + # of neutrons

Atomic Number: The # of protons in the nucleus of an atom

Electronegativity: Tendency for an atom to attract/want/desire electrons

As the periodic table progresses, from the bottom left to the upper right, respective elements are more electronegative.

Atoms want to have/want to get rid of electrons to be stable and have a full outer shell of electrons.

Noble Gases: The elements on the rightmost column of the periodic table. Have a full outer shell of electrons & do not react.

Lowest energy level outside the nucleus holds a maximum of 2 electrons

Every other energy level outside the nucleus holds a maximum of 8 electrons

An ion is stable, but not neutral.

Valence Electrons: Electrons in the outermost shell

Ionic Bond: When one atom completely donates an electron to another atom. Ex. NaCl (table salt)

Covalent Bond: When 2 atoms share electrons

Polarity: Electrons are unevenly distributed among the atoms connected by a chemical bond.

Polar Molecule: Partially positive side, partially negative side.

Nonpolar Molecule: Electrons are shared evenly, with no partial charges.

Hydrogen Bond: Water molecules weakly attract each other at the partial positive side of one molecule and the partial negative side of another.

Molecule: 2 or more atoms held together by bonds.

Compound: Substance made up of 2 or more atoms of different elements.

Chemical Change: A chemical reaction forms new products

Physical Change: Matter changes form but not chemical identity.

Solvent = liquid, solute = particles that dissolve, solution = mixture.

pH: power of Hydrogen; a measure of hydrogen ion concentration.

Acids: increase the hydrogen ion concentration of a water solution.

Bases: decrease the hydrogen ion concentration of a water solution.

Most Biological reactions occur at pH 7

pH Scale: Ranges from 0-14; any value below 7 is an acid, any value above 7 is a base.

The higher the pH, the more basic/less hydrogen ion concentrated the solution is.

Buffers: any compound(s) that can both increase or decrease the hydrogen ion concentration in order to maintain homeostasis.

Carbonic Acid: Bicarbonate Buffer system.

Properties of Water: Universal Solvent, Cohesion, Adhesion, High specific heat, High heat of vaporization, Density Changes

Polarity of the water molecule means that it can attract other molecules that are charged/polar.

Dissociate: compound breaks into ions in a solution

Cohesion: Water is attracted to other water molecules due to hydrogen bonding. Causes high surface tension.

Adhesion: Water is attracted to other substances that are polar/charged.

Capillary action: Water sticks to walls of plant cell capillaries and travels up the plant

High specific heat: Water temperature changes slowly and holds temperature well.

High Heat of Vaporization: Water requires a lot of energy to change state. Ex. When organisms sweat/dogs pant, they release a high amount of heat energy.

Density Changes: Ice floats, solid water molecules form a lattice that is less dense than liquid water, and therefore floats.