A.p. Chemistry Vocabulary

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chemistry

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the study of the properties of materials and the changes that materials undergo

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matter

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the physical material of the universe; anything that has mass and occupies space

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elements

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a substance that cannot be separated into simpler substances by chemical means

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atoms

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the almost infinitesimally small building blocks of matter.

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molecule

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a chemical combination of two or more atoms

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gas

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state of matter that has no fixed volume or shape and takes the shape and volume of its container

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liquid

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state of matter with a distinct volume but no specific shape.

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solid

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state of matter that has a definite shape and a definite volume

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states of matter

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the forms that matter can assume: solid, liquid, gas

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mixture

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combinations of tow or more substances in which each substance retains its own chemical identity and hence its own properties

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solutions

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a mixture of substances that has a uniform composition; a homogeneous mixture

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pure substance

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matter that has a fixed composition and distinct properties

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compounds

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are composed of tow or more elements with the atoms bonded together

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law of constant composition

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the observation that the elemental composition of a pure compound is always the same

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law of definite proportions

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same as the law of constant composition. The observation that the elemental composition of a pure compound is always the same.

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physical properties

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properties that can be measured without changing the composition of a substance, for example, color and freezing point

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chemical properties

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describe the way a substance may change or react to form other substances.

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physical change

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when a substance changes its physical appearance but not its composition

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change of state

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physical changes of a substance is transformed into a chemically different substance

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chemical change

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when a substance is transformed into a chemically different substance.

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chemical reaction

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process in which on or more substances are converted into other substances.

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intensive properties

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properties that do not depend on the amount of the sample being examined

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extensive properties

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depend on the quantity of the sample and include measurements of mass and volume

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scientific method

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the general process of advancing scientific knowledge by making experimental observations and by formulating laws, hypotheses, and theories

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scientific law

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a concise verbal statement or a mathematical equation that summarized a broad variety of observations and experiences.

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hypothesis

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a tentative explanation of a series of observations or of a natural law

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theory

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an explanation of the general principles of certain phenomena with considerable evidence or facts to support it.

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metric system

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the units used for scientific measurements

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SI unit

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the preferred metric units for use in science

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mass

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a measure of the amount of material in an object

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Kelvin scale

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the SI temperature scale, with zero being the lowest

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Celsius scale

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temperature scale. water boils at 100 degress and freezes at 0.

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density

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defines as the amount of mass in a unit volume of the substance. mass/volume

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precision

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a measure of how closely individual measurements agree with one another.

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accuracy

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how closely individual measurements agree with the correct, or true value

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significant figures

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the digits that indicate the precision with which a measurement is made; all digits of a measured quantity are significant, including the last digit, which is uncertain.

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dimensional analysis

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a method of problem solving in which units are carried through all calculations, ensures that the final answer of a calculation has the desired units.

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conversion factor

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a fraction whose numerator and denominator are the same quantity expressed in different units

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qualitative measurement

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measurement without using numbers to describe it. based on observations, not mathematical measurements.

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quantitative measurements

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measured using numbers for observation. quantity, amount.

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atoms

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the basic building blocks of matter

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subatomic particles

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the smaller than atom particles that make up atoms

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cathode rays

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streams of electrons that are produced when a high voltage is applied to electrodes in an evacuated tube.

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radioactivity

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the spontaneous emission of radiation

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nucleus

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the very small, dense region in the atom where all of the positive charge is located.

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protons

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subatomic particle with a positive charge; located in the nucleus

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neutrons

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subatomic particle without charge; located inside the nucleus

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electrons

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subatomic particle with negative charge; located outside the nucleus in the atom

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Law of Electrostatic Attraction

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states that like charged repel one another, unlike charged attract

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electronic charge

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the negative charge carried by an electron; it has a magnitude of 1.601 x 10^-19 C.

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atomic mass unit

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the unit of mass measurement to express the small mass of atoms

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angstroms

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unit of length used to express atomic dimensions

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atomic number

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the number of protons in an atom

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mass number

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the total number of protons and neutrons in the atom

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isotopes

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atoms of a given element that differ in the number of neutrons

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nuclide

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an atom of a specific isotope

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periodic table

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the arrangement of elements in order of increasing atomic number, with elements having similar properties placed in vertical columns.

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group

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the elements in a column of the periodic table

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metallic elements

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all the elements on the left side and in the middle of the periodic table

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nonmetallic elements

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elements in the upper-right corner of the periodic table; nonmetals differ from metals in their physical and chemical properties

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metalloids

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the elements that lie along the line that separates metals from nonmetals have properties that fall between those of metals and nonmetals

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molecules

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an assembly of tow or more atoms tightly bound together.

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molecular compounds

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compounds that are composed of molecules and contain more than one type of atom

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chemical formula

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a notation that uses chemical symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a substance

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empirical formula

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chemical formulas that give only the relative number of atoms in each type in a molecule

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molecular formula

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chemical formulas that indicate the actual numbers and types of atoms in a molecule

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structural formula

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shows which atoms are attached to which within the molecule

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ions

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a charged particle that is formed when electrons are removed or added to a neutral atom

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cations

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an ion with a positive charge

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anions

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a negatively charged ion

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ionic compounds

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a compound that contains positively charged ions and negatively charged ions

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polyatomic ions

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ions that consist of atoms joined as in a molecule, but they have a net positive or negative charge.

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oxyanions

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polyatomic anions containing oxygen; have names ending in -ate or -ite

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binary compound

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compound composed of two elements

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stoichiometry

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the relationships among the quantities of reactants and the products involved in chemical reactions.

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law of conservation of mass

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scientific law stating that the total mass of the products of a chemical reaction is the same as the total mass of the reactants, so that mass remains constant during the reaction

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chemical equation

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a representation of a chemical reaction using the chemical formulas of the reactants and products

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reactants

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the chemical formulas on the left of the arrow; the starting substances in a chemical reaction

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products

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the substances produced in a chemical reaction; shown on the right of the arrow

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combustion reactions

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rapid reactions that produce a flame; most involve oxygen; uses heat

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combination reactions

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tow or more substances react to form one product

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decomposition reactions

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one substance undergoes a reaction to produce tow or more other substances.

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atomic weight

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the average atomic mass of each element

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atomic mass units (amu)

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a unit based on the value of exactly 12 amu for the mass of the isotope of carbon that has six protons and six neutrons in the nucleus

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formula weight

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the sum of the atomic weights of each atoms in its chemical formula

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molecular weight

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the mass of the collection of atoms represented by the chemical formula for a molecule

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mass spectrometer

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an instrument used to measure the precise masses and relative amounts of atomic and molecular ions.

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mole

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a collection of Avagadro's number (6.022 x10^23) of objects.

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Avagadro's number

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6.022 x10^23
number used with moles

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molar mass

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the mass in grams of 1 mol of a substance

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empirical formula

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a chemical formula that shows the kinds of atoms and their relative numbers in a substance

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molecular formula

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a chemical formula that indicates the actual number of atoms of each element in a substance.

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limiting reagent (reactant)

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the reactant that is completely consumed in a reaction. Limits the amount of product formed.

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Theoretical yield

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the quantity of product that is calculated to form when all of the limiting reactant reacts.

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percent yield

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relates the actual yield to the theoretical yield.
(actual/theoretical)*100

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aqueous solutions

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solutions in which water is the dissolving medium

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solvent

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the substance in a solution that does the dissolving

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solute

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the substance in a solution that is dissolved

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electrolyte

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a substance whose aqueous solutions contain ions and hence conduct electricity

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nonelectrolyte

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a substance that does not form ions in solution

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strong electrolyte

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a substance that is completely ionized in solution, for example, strong acids, strong bases and most salts

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weak electrolyte

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a substance that only partly ionizes in solution

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chemical equilibrium

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a state of dynamic balance in which the rate of formation of the products of a reaction form the reactants equals the rate of formation of the reactants from the products

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precipitation reaction

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reactions that result in the formation of an insoluble product

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precipitate

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an insoluble solid formed by a reaction in solution

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solubility

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the amount of that substance that can be dissolved in a given quantity of solvent

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exchange(metathesis) reaction

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reactions in which positive ions and negative ions appear to exchange partners. (double replacement)

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molecular equation

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a chemical equation in which the formula for each substance is written without regards for whether it is an electrolyte or a nonelectrolyte

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complete ionic equation

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a chemical in which dissolved strong electrolytes are written as separate ions.

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net ionic equation

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the equation left after the spectator ions are omitted from the equation

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strong base

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a base that ionizes completely in water

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spectator ion

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ions that appear in identical forms among both the reactants and the products of a complete ionic equation

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base

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substances that accept H+ atoms

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acid

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substances that are able to ionize in aqueous solutions to form a hydrogen ion and thereby increase the concentration of H+ atoms

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strong acid

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an acid that ionizes completely in water.

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weak acid

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an acid that partly ionizes in water

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weak base

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a base that partly ionizes in water

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neutralization reaction

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when a solution of an acid and that of a base are mixed

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salt

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any ionic compound whose cation comes from a base and whose anion comes from an acid

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oxidation

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loss of electrons by a substance

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reduction

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the gains of electrons by a substance

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oxidation number

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a positive or negative whole number assigned to an element in a molecule or ion on the basis of a set of formal rules

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displacement reaction

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a reaction in which an element reacts with a compound, displacing an element from it.

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activity series

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a list of metals arranged in order of decreasing ease of oxidation

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concentration

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the quantity of solute present in a given quantity of solvent or solution

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molarity

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the number of moles of solute in a liter of solution

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dilution

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the process of lowering the concentration of a solution by adding water

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titration

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the process of reacting a solution of unknown concentration with one of known concentration

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standard solution

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a solution of known concentration

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equivalence point

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the point at which stoichiometrically equivalent quantities are brought together.

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indicator

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a substance added to a solution to indicate by a color change the point at which the added solute has reacted with all the solute present in solution

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intensive property

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property that is independent of the amount of material considered

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extensive property

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a property that depends on the amount of the material considered