Chapter 2: Life's Chemical Basis

Particle that is a fundamental building block of matter; consists of varying numbers of electrons, protons, and neutrons

Positively charged subatomic particle in the nucleus of all atoms. The number of protons (the atomic number) defines the element

Uncharged subatomic particle in the atomic nucleus

Negatively charged subatomic particle that occupies orbitals around the atomic nucleus

The positively charged dense center of an atom

The number of protons in the nucleus of atoms of a given element

A substance that consists only of atoms with the same number of protons

Forms of an element that differ in the number of neutrons their atoms carry

Total number of protons and neutrons in the nucleus of an element's atoms

Isotope with an unstable nucleus; decays into predictable daughter elements at a predictable rate

Process by which atoms of a radioisotope spontaneously emit energy and subatomic particles when their nucleus disintegrates

A molecule with a detectable label attached; researchers can track it after delivering it into a cell or other system

positron emission tomography scan; a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

A three-dimensional region around the nucleus that indicates the probable location of an electron

Model of electron distribution in an atom; orbitals are shown as nested circles, electrons as dots; 2-8-8-18

Atom that carries a charge because of an unequal number of protons and electrons

An atom or group of atoms with at least one unpaired electron

A measure of an atom's ability to pull electrons away from other atoms

An attractive force that arises between two atoms when their electrons interact

Group of two or more atoms joined by chemical bonds

Type of molecule that has atoms of more than one element

Two or more types of molecules intermingled in proportions that vary

Type of chemical bond; strong mutual attraction between ions of opposite charge

Chemical bond in which two atoms share a pair of electrons

A type of covalent bond in which two atoms share two pairs of electrons; symbolized by a pair of lines between the bonded atoms

A type of covalent bond in which three pairs of electrons are shared by two atoms

A covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

Any separation of charge into distinct positive and negative regions

Attraction that forms between a covalently bonded hydrogen atom and an electronegative atom taking part in a separate covalent bond

Substance, typically a liquid, that can dissolve other substances; e.g., water

A dissolved substance

Describes a substance that dissolves easily in water; e.g., a salt Having a strong affinity for water

Describes a substance that resists dissolving in water; e.g., an oil Lacking affinity for water

Measure of molecular motion

Transition of a liquid to a gas; requires energy input

Tendency of molecules to stick together under tension; a property of liquid water

an atom of hydrogen that has lost its electron. they are the key to the reactions of acids

released from bases when added to water

A measure of the number of hydrogen ions in a solution

Any substance that releases hydrogen ions in water

A substance that accepts hydrogen ions as it dissolves in water

Compound that dissolves easily in water and releases ions other than H+ and OH-

Set of chemicals that can keep the pH of a solution stable by alternately donating and accepting ions that contribute to pH