Key Terms For Campbell Biology 6E: Unit One

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anion

Back 1

a negatively charged ion

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atom

Back 2

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

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atomic nucleus

Back 3

An atom's central core, containing protons and neutrons

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atomic number

Back 4

The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol.

Front 5

atomic weight

Back 5

The total atomic mass, which is the mass in grams of one mole of a the atom.

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cation

Back 6

An ion with a positive charge, produced by the loss of one or more electrons.

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chemical bond

Back 7

An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms; the bonded atoms gain complete outer electron shells.

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chemical equilibrium

Back 8

In a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction.

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chemical reaction

Back 9

A process leading to chemical changes in matter; involves the making and/or breaking of chemical bonds

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compound

Back 10

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

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dalton

Back 11

A measure of mass for atoms and subatomic particles.

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double covalent bond

Back 12

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

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electron shell

Back 13

An energy level representing the distance of an electron from the nucleus of an atom

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electron

Back 14

A subatomic particle with a single negative charge; one or more electrons move around the nucleus of an atom.

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electronegativity

Back 15

The attraction of an atom for the electrons of a covalent bond.

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element

Back 16

Any substance that cannot be broken down to any other substance.

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energy level

Back 17

The different states of potential energy for electrons in an atom.

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energy

Back 18

The capacity to do work (to move matter against an opposing force).

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hydrogen bond

Back 19

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

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ion

Back 20

An atom that has gained or lost electrons, thus acquiring a charge.

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ionic bond

Back 21

A chemical bond resulting from the attraction between oppositely charged ions.

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ionic compound

Back 22

Compounds resulting from the formation of ionic bonds, also called a salt.

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isotope

Back 23

One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.

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mass number

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The sum of the number of protons and neutrons in an atom's nucleus.

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matter

Back 25

Anything that takes up space and has mass.

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molecular formula

Back 26

A type of molecular notation indicating only the quantity of the constituent atoms.

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molecule

Back 27

Two or more atoms held together by covalent bonds.

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neutron

Back 28

An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom.

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nonpolar covalent bond

Back 29

A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.

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potential energy

Back 30

The energy stored by matter as a result of its location or spatial arrangement.

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product

Back 31

An ending material in a chemical reaction.

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proton

Back 32

A subatomic particle with a single positive electrical charge, found in the nucleus of an atom.

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radioactive isotope

Back 33

An isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.

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reactant

Back 34

A starting material in a chemical reaction.

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salt

Back 35

Compounds resulting from the formation of ionic bonds, also called an ionic compound.

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structural formula

Back 36

A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds.

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trace element

Back 37

An element indispensable for life but required in extremely minute amounts.

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valence electron

Back 38

The electrons in the outermost electron shell.

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valence shell

Back 39

The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

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valence

Back 40

The bonding capacity of an atom generally equal to the number of unpaired electrons in the atom's outermost shell.

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Van der Waals interactions

Back 41

Weak attractions between molecules or parts of molecules that are brought about by localized charge fluctuations.