Chemistry - Chapter 2 Vocab

Front 1

Element

Back 1

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

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Substance

Back 2

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

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Molecule

Back 3

a structure consisting of two or more atoms that are chemically bound together and behave as an individual unit

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Compound

Back 4

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

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Mixture

Back 5

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

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Law of Mass Conservation

Back 6

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

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Law of Definite (or Constant) Composition

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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

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Fraction by Mass (mass fraction)

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the portion of a compound's mass contributed by an element; the mass of an element in a compoud divided by the mass of the compound

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Percent by Mass (mass %)

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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

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Law of Multiple Proportions

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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

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Atom

Back 11

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

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Cathode Ray

Back 12

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

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Nucleus

Back 13

the tiny central region of the atom that contains all the postive charge and essentially all the mass

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Proton

Back 14

(P^+)

a subatomic particle found in the nucleus that has a unit postive charge

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Neutron

Back 15

(n^0)

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

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Electron

Back 16

(e^-)

a subatomic particle that possesses a unit negative charge and occupied the space around the atomic nucleus

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Atomic Number

Back 17

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 or a nucleus in multiples of the electronic charge

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Mass Number

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A

the total number of protons and neutrons of an atom

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Atomic Symbol

Back 19

a one- or two- letter abbrevation for the English, Latin, or Greek name of an element

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Isotope

Back 20

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

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Atomic Mass Unit

Back 21

(amu)

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

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Dalton

Back 22

Da

a unit of mass identical to atomic mass unit

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Mass Spectrometry

Back 23

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

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Isotopic Mass

Back 24

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

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Atomic Mass

Back 25

(atomic weight)

the average of the masses of the naturally occurring isotopes of an element weighted according to their abundances

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Periodic Table of the Elements

Back 26

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

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Period

Back 27

a horizontal row on the periodic table

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Group

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a vertical column in the periodic table

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Metal

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a substance or mixture that is relatively shiny and malleable and is a good conductor of head and electricity. in reactions, metals tend to transfer electrons to nonmetals and form ionic compounds

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Nonmetal

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

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Metalloid (Semimetal)

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an element with properties between those of metals and nonmetals

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Ionic Compound

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a compound that consists of oppositely charged ions

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Covalent Compound

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a compound that consists of atoms bonded together by shared election pairs

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Chemical Bond

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the force that holds two or more atoms together in a molecule (or formula unit)

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Ion

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

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Binary Ionic Compound

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a compund that consists of the oppositely charged ions of two elements

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Cation

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a positively charged ion

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Anion

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a negatively charged ion

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Monatomic Ion

Back 39

an ion derived from a single atom

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Covalent Bond

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

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Polyatomic Ion

Back 41

an ion in which two or more atoms are bonded covalently

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Chemical Formula

Back 42

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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Emperical Formula

Back 43

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

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Molecular Formula

Back 44

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

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Structural Formula

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

Front 46

Formula Unit

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

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Oxoanion

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

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Hydrate

Back 48

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

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Binary Covalent Compund

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a compund that consists of atoms of two elements in which bonding occurs primarily through electron sharing

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Molecular Mass

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(molecular weight)

the sum (in amu) of the atomic masses of a formula unit of a compound

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Formula Mass

Back 51

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

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Heterogeneous Mixture

Back 52

a mixture that has one or more visible boundaries among its compounds

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Homogeneous Mixture

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(also solution)

a mixture that has no visible boundaries among its components

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Aqueous Solution

Back 54

a solution in which water is the solvent