E AP Bio Unit 1 Topic 1

Matter

Anything that takes up space and has mass

Element

A substance that cannot be broken down into other substances by chemical reactions

Electronegativity

The measure of an atom’s ability to attract electrons to itself

Atomic number

Number of protons an atom has

Atomic mass

Number of protons plus neutrons averages over all isotopes

Octet rule

Elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)

Chemical bonds

An attraction between two atoms, resulting from the sharing or transferring of valence electrons

Compound

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

Covalent bonds

When two or more atoms share electrons (usually between two nonmetals)

Nonpolar covalent bonds

Electrons are shared equally between two atoms

Polar covalent bonds

Electrons are not shared equally between two atoms

Ionic bonds

The attraction between oppositely charged atoms (ions)

Adhesion

The attraction to other molecules that are polar or have charge (H2O to other molecules)

Cohesion

Attraction of molecules for other molecules of the same kind (H2O to H2O)

Capillary action

The upward movement of water due to the forces of cohesion, adhesion, and surface tension

Solvent

Dissolving agent in a solution (water is a universal solvent)

Solution

Homogeneous mix of 2+ substances (salt+water)

Solute

Substance that is dissolved

pH (acid vs base)

Acids release hydrogen ions (H+) when dissolved in water

Bases accept H+ OR releases hydroxide ions (OH-)

Buffer

A solution that resists changes in pH when an acid or base is added

Identify the elements that make up nearly all living matter

CHOPNS: Carbon, hydrogen, oxygen, phosphorous, nitrogen, sulfur

Differentiate between a solute, solvent, and a solution

Solute-substance that dissolves

Solvent-dissolving agent

Solution-homogenous mixture of two substances

Describe covalent bonds and give two examples

Bonds where electrons are shared between atoms-O2, C2

Describe ionic bonds and give two examples

Electrons are transferred from a metal to a nonmetal-NaCl, KCl

How are hydrogen bonds different from other types of bonds?

Hydrogen bonds are between two molecules of the same substance

How does electronegativity affect the interactions between water molecules?

Electronegativity causes water molecules to be attracted to each other

If O and H had the same electronegativity, what would that do to the properties of water?

Water would no longer be polar, so it would not have cohesion and adhesion and the specific heat would be lower.