Che101 - Chapter 2 - Summer 2009

Front 1

anion

Back 1

A negatively charged ion.

Front 2

aqueous solution

Back 2

A solution in which water is the solvent.

Front 3

atom

Back 3

The smallest particle of an element that retains the chemical nature of the element. A neutral, spherical entity composed of a positively charged central nucleus surrounded by one or more negatively charged electrons.

Front 4

atomic mass

Back 4

(also atomic weight) The average of the masses of the naturally occurring isotopes of an element weighted according to their abundances.

Front 5

atomic mass unit (amu)

Back 5

[also dalton (Da)] A mass exactly equal to 1/12 the mass of a carbon-12 atom.

Front 6

atomic number (Z)

Back 6

(Z) The unique number of protons in the nucleus of each atom of an element (equal to the number of electrons in the neutral atom). An integer that expresses the positive charge of a nucleus in multiples of the electronic charge.

Front 7

atomic symbol

Back 7

(or element symbol) A one- or two-letter abbreviation for the English. Latin, or Greek name of an element

Front 8

binary covalent compound

Back 8

A compound that consists of atoms of two elements in which bonding occurs primarily through electron sharing.

Front 9

binary ionic compound

Back 9

A compound that consists of the oppositely charged ions of two elements.

Front 10

cathode ray

Back 10

The ray of light emitted by the cathode (negative electrode) in a gas discharge tube; travels in straight lines, unless deflected by magnetic or electric fields.

Front 11

cation

Back 11

A positively charged ion.

Front 12

chemical bond

Back 12

The force that holds two atoms together in a molecule (or formula unit).

Front 13

chemical formula

Back 13

A notation of atomic symbols and numerical subscripts that shows the type and number of each atom in a molecule or formula unit of a substance.

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composition

Back 14

The types and amounts of simpler substances that make up a sample of matter.

Front 15

compound

Back 15

A substance composed of two or more elements that are chemically combined in fixed proportions.

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covalent bond

Back 16

A type of bond in which atoms are bonded through the sharing of two electrons; the mutual attraction of the nuclei and an electron pair that holds atoms together in a molecule.

Front 17

covalent compound

Back 17

A compound that consists of atoms bonded together by shared electron pairs.

Front 18

dalton (Da)

Back 18

A mass exactly equal to 1/12 the mass of a carbon-12 atom.

Front 19

electron (e~)

Back 19

A subatomic particle that possesses a unit negative charge (.60218X 10-19 C) and occupies the space around the atomic nucleus.

Front 20

element

Back 20

The simplest type of substance with unique physical and chemical properties. An _______ consists of only one kind of atom, so it cannot be broken down into simpler substances.

Front 21

empirical formula

Back 21

chemical formula that shows the lowest relative numbers of atoms of elements in a compound.

Front 22

formula mass

Back 22

The sum (in amu) of the atomic masses of a formula unit of an ionic compound.

Front 23

formula unit

Back 23

The chemical unit of a compound that contains the number and type of atoms (or ions) expressed in the chemical formula.

Front 24

fraction by mass

Back 24

(also mass fraction) The portion of a compound's mass contributed by an element: the mass of an element in a compound divided by the mass of the compound.

Front 25

group

Back 25

A vertical column in the periodic table.

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heterogeneous mixture

Back 26

A mixture that has one or more visible boundaries among its components

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homogeneous mixture

Back 27

(also solution) A mixture that has no visible boundaries among its components.

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hydrate

Back 28

A compound in which a specific number of water molecules are associated with each formula unit.

Front 29

ion

Back 29

A charged particle that forms from an atom (or covalently bonded group of atoms) when it gains or loses one or more electrons.

Front 30

ionic compound

Back 30

A compound that consists of oppositely charged ions.

Front 31

isotope

Back 31

Atoms of a given atomic number (that is. of a specific element) that have different numbers of neutrons and therefore different mass numbers.

Front 32

isotopic mass

Back 32

The mass (in amu) of an isotope relative to the mass of the carbon-12 isotope.

Front 33

law of definite (or constant) composition

Back 33

A mass law stating that, no matter what its source, a particular compound is composed of the same elements in the same parts (fractions) by mass.

Front 34

law of mass conservation

Back 34

A mass law stating that the total mass of substances does not change during a chemical reaction.

Front 35

law of multiple proportions

Back 35

A mass law stating that if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers.

Front 36

percent mass

Back 36

The fraction by mass expressed as a percentage. A concentration term [% (w/w)] expressed as the mass in grams of solute dissolved per 100. g of solution.

Front 37

mass spectrometry

Back 37

An instrumental method for measuring the relative masses of particles in a sample by creating charged particles and separating them according to their mass-charge ratio.

Front 38

metal

Back 38

A substance or mixture that is relatively shiny and malleable and is a good conductor of heat and electricity. In reactions, ______ tend to transfer electrons to nonmetals and form ionic compounds

Front 39

metalloid (semimetal)

Back 39

An element with properties between those of metals and nonmetals.

Front 40

mixture

Back 40

A group of two or more elements and/or compounds that are physically intermingled.

Front 41

molecular formula

Back 41

A formula that shows the actual number of atoms of each element in a molecule.

Front 42

molecular mass

Back 42

(or molecular weight) The sum (in amu) of the atomic masses of a formula unit of a compound.

Front 43

molecule

Back 43

A structure consisting of two or more atoms that are chemically bound together and behave as an independent unit.

Front 44

monatomic ion

Back 44

An ion derived from a single atom.

Front 45

neutron (n°)

Back 45

An uncharged subatomic particle found in the nucleus, with a mass slightly greater than that of a proton.

Front 46

nonmetal

Back 46

An element that lacks metallic properties. In reactions, _________ tend to bond with each other to form covalent compounds or accept electrons from metals to form ionic compounds.

Front 47

nucleus

Back 47

The tiny central region of the atom that contains all the positive charge and essentially all the mass.

Front 48

oxoanion

Back 48

An anion in which an element is bonded to one or more oxygen atoms.

Front 49

percent by mass (mass %)

Back 49

The fraction by mass expressed as a percentage. A concentration term [% (w/w)] expressed as the mass in grams of solute dissolved per 100. g of solution.

Front 50

period

Back 50

A horizontal row of the periodic table.

Front 51

periodic table of the elements

Back 51

A table in which the elements are arranged by atomic number into columns (groups) and rows (periods).

Front 52

polyatomic ion

Back 52

An ion in which two or more atoms are bonded covalently.

Front 53

proton (p+)

Back 53

A subatomic particle found in the nucleus that has a unit positive charge (.60218x10-19 C)

Front 54

solution

Back 54

homogeneous mixture

Front 55

structural formula

Back 55

A formula that shows the actual numbers of atoms, their relative placement, and the bonds between them.

Front 56

substance

Back 56

A type of matter, either an element or a compound, that has a fixed composition.