Chapter 2: Chemical Basis of Life: Elements and Bonds

Matter

Substance composed of atoms

Ionic Bond

Bond formed by transfer of electrons

Covalent Bond

Bond formed by sharing a pair of electrons

Cation

Positively charged ion

Anion

Negatively charged ion

Compound

Substance composed of two or more elements

Molecule

Consists of two or more atoms held by bonds

Metal

Element with metallic properties

Metalloid

Element with properties between metals and nonmetals

Non-metal

Element lacking metallic properties

Noble Gas

Element with stable and inert characteristics

Atomic Structure

Composition of an atom's nucleus and electron cloud

Atomic Properties

Distinct characteristics of each element's atoms

Electron Cloud

Space around the nucleus occupied by electrons

Double Covalent Bond

Sharing two pairs of valence electrons

Dinitrogen

Molecule with three covalent bonds (N2)

Single Covalent Bond

Sharing one pair of valence electrons

Methane

Example of a molecule with four covalent bonds (CH4)

Polar Molecule

Unequal charge distribution, like water

Hydrogen Bond

Attraction between partially charged atoms

Hydrophilic

Molecules attracted to water due to polarity

Hydrophobic

Molecules not attracted to water due to nonpolarity

Cohesion

Water molecules clinging together via hydrogen bonds

Adhesion

Water molecules clinging to other polar surfaces

Specific Heat

Amount of heat to change temperature by 1ºC

Heat of Vaporization

Heat needed to convert 1g of liquid to gas

Acids

Release hydrogen ions when dissociated

Bases

Release hydroxide ions when dissociated

pH Scale

Indicates acidity/basicity based on H+ concentration

Buffers

Substances that resist pH changes

Acidosis

Condition of high acidity in the body

Carbonic Acid

Buffer maintaining blood pH near neutral

Atom

Smallest particle of an element retaining its characteristics. Its the building block of matter

Nucleus

Dense center of an atom

Electron

Negatively charged subatomic particle

Proton

Positively charged subatomic particle

Neutron

Subatomic particle with no charge

Atomic Number

Number of protons in an atom

Atomic Mass

Number of particles in the nucleus

Valence Shell

Outermost electron shell determining chemical behavior