AP Bio Unit 1

An element

a substance that cannot be broken down to other substances by chemical reactions

A compound

substance consisting of two or more elements in a fixed ratio

Carbon, hydrogen, oxygen, nitrogen

make up 96% of living matter

Remaining 4% of living matter

Calcium, Phosphorous, Potassium, Sulfur

Atom

The smallest unit of matter that still retains the properties of an element

Neutrons and protons

form the atomic nucleus and measured in daltons

Atomic number

number of protons in a nucleus, can be approximated by the mass number

Mass number

Sum of protons plus neutrons in the nucleus

All atoms of an element

Have the same number of protons but may differ in number of neutrons

Isotopes

two atoms of an element that differ in number of neutrons

Parent isotope

decays into daughter isotope (half-life)

Potential energy

The energy that matter has because of its location or structure

Electron shell

An electron’s state of potential energy (energy level), determines chemical behavior via distribution

Valence electrons

Those in the outermost shell / valence shell, heavily determines chemical behavior

Orbital

Three-dimensional space where electron is found 90% of the time

Chemical bonds

Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms, resulting in atoms staying close together

Covalent bond

The sharing of a pair of valence electrons by two atoms; the shared electrons count as part of each atom’s valence shell; can form between atoms of any kind

Molecule

Consists of two or more atoms held together by covalent bonds

Electronegativity

an atom’s attraction for the electrons in a covalent bond; more electronegativity -> stronger attraction

Nonpolar covalent bond

Atoms share electron equally

Polar covalent bond

Atoms share electron unequally, causing partial charge for each atom or molecule

Ion

A charged atom or molecule

An ionic bond

an attraction between an anion and a cation

Ionic compounds

compounds formed by ionic bonds or salts

Hydrogen bond

Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom

Van der Waals interactions

attractions between molecules that are close together as a result of charges

Chemical reactions

The making and breaking of chemical bonds

Reactants

Starting molecule of a chemical reaction

Products

Final molecules of a chemical reaction

Chemical equilibrium

reached when the forward and reverse reactions occur at the same rate

In the water molecule

The electrons of the polar covalent bonds spend more time near the oxygen than the hydrogen, making water a polar molecule with overall charge unevenly distributed; this allows water to form hydrogen bonds

Cohesion

Hydrogen bonds hold water molecules together

Adhesion

the attraction between different substances, for example, between water and plant cell walls

Surface tension

A measure of how difficult it is to break the surface of a liquid

Water has an

usually high surface tension due to hydrogen bonding

Kinetic energy

the energy of motion

Temperature

the average kinetic energy of the molecules in a body of matter

Heat

Thermal energy transferred from one body of matter to another, which is random motion of atoms or molecules

Calorie

Amount of heat to raise the temperature of 1 g of water by 1 C

Specific heat

The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 C

Water’s high specific heat

Heat is absorbed when hydrogen bonds break, heat is released when hydrogen bonds form

Heat of vaporization

The heat a liquid must absorb for 1 g to be converted to gas

Ice floats in liquid water because

Hydrogen bonds in ice are more “ordered”, making ice less dense than water

Solution

a liquid that is completely homogenous mixture of substances

SOLVENT

DISSOLVING AGENT

Solute

substance that is dissolved

Aqueous solution

One in which water is the solvent

Hydration shell

When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules

Molarity

The number of moles of solute per liter of solution

Hydrogen ion

the hydrogen atom that leaves it electron behind and becomes a proton

Hydroxide ion

the molecule that lost the proton

Hydronium ion

The molecule with the extra proton

Acid

Increases the H concentration; ph value less than 7

Base

reduces the H concentration; ph value greater than 7

Strong acids and bases

dissociate completely in water

Buffers

substances that minimize changes in concentration of H and OH

Dehydration reaction

Two monomers bond together through the loss of water molecule

Hydrolysis

Polymers are disassembled to monomers by adding water

Starch

A storage polysaccharide of plants, consists of glucose monomers <- Carbohydrate

Glycogen

A storage polysaccharide in animals

Cellulose

A major component of the tough wall of plant cells

Chitin

found in the exoskeleton of arthropods

Lipids

hydrophobic, does not include true polymers

Unsaturated and Saturated

Liquid (BENT), Solid

Amino acids

monomers that create polypeptides that are linked by covalent bonds called peptide bonds

Gene expression

DNA directs synthesis of mRNA to control protein synthesis

Nucleic acids

polymers called polynucleotides which are made up of nitrogenous base, a pentose sugar, and one or more phosphate group

Pyrimindines

Cytosine, Thymine, and Uracil (SMALLER)

Purines

Adenine and guanine (LARGER)

DNA Backbones

Run in opposite 5 to 3, antiparallel