1St Semester Chemistry Exam

Front 1

smallest particle of an element that can enter into chemical change & retains the properties of that element

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atom

Front 2

the exact mass of an atom

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atomic mass

Front 3

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

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atomic mass unit

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the number of protons in the nucleus of an atom of an element

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atomic number

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an instrument used to measure atmospheric pressure

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barometer

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turbulence in a liquid caused by the rapid formation of bubbles of vapor at the boiling point

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boiling

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substance that changes the speed of a chemical reaction without being permanently altered itself

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catalyst

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an ion carrying a positive charge

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cation

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a condensed statement that uses formulas to show the reactants & products in a chemical change

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chemical equation

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an action that produces a chemical change

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chemical reaction

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a substance of definite composition, which may be decomposed into two or more simpler substances by chemical change

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compound

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shows the number & type of atoms of a substance

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chemical formula

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substance formed in a chemical reaction

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product

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a solid consisting of plane faces & having a definite shape. the atoms are arranged in a repeated pattern

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crystal

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mass per unit volume

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density

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The process in which a liquid is evaporated

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distillation

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The formula showing the simplest ration in which the atoms combine to form a compound

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empirical

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The escape of molecules from a liquid into the gaseous phase

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vaporization

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Proposed explanation of observed facts or events, it is subjected to confirmation by further observations & experimentation

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hypothesis

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at atom or a group of atoms with an excess positive or negative charge

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ions

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atoms of the same element having different mass numbers due to the different number of neutrons in their nuclei

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isotopes

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the theory that explains the properties of matter in terms of molecular motion

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kinetic theory

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the total number of protons & neutrons in the nucleus of an atom

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mass number

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an association of two or more substances that are not chemically combined

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mixture

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the volume occupied by a gram, molecular mass of a gas or vapor. this volume is 22.4 liters at standard conditions

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molar volume

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the Avogadro number of any particle of definite composition. quantity of a substance that has a mass in gram numerically equal to its molecular mass

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mole

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a formula that indicates the actual number of atoms of each element in one molecule of a substance

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molecular formula

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the mass of a molecule in atomic mass units

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molar mass

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the SI unit of pressure

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pascal

Front 30

a change in which the composition & chemical properties of a substance are not altered

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physical change

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a characteristic of a material that can be observed without a chemical change taking place

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physical properties

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a particle made up of two or more elements that carries a net electrical charge & acts as a unit in chemical change. the bonds between the atoms of the ion are covalent. sometimes called an ionic radical.

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polyatomic ion

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a measure of the agreement between the numerical values of two or more measurements that have been made using the same methods

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precision

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one of the starting substances involved in a chemical reaction

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reactant

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statement of a relationship between observed facts. it may be a qualitative statement of a mathematical formula

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scientific law

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the ration of the mass of a given volume of a substance to that of an equal volume of a standard. water is the standard for liquids & solids; hydrogen, oxygen, or air may be used for gases

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specific gravity

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the name given to the study of the quantitative relationships that can be derived from formulas & equations

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stoichiometry

Front 38

the change of a solid to a vapor(or the reverse) without passing through the liquid phase

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sublimation

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is a broad & extensively tested explanation of why experiments give certain results. can never be proved because it is always possible for a new experiment to disprove it

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scientific theory

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the first theory to relate chemical changes to events at the atomic level. all elements are composed of tiny indivisible particles called atoms

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Dalton's atomic theory

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first suggested the existence of particles, he called atoms

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Democritus

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proposed atom is mostly empty space, all positive charges & almost all the mass are concentrated in a small region called the nucleus

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Rutherford

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stated by Dalton; whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers

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Law of Multiple Proportions

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states that in samples of any chemical compound, the masses of the elements are always in the same proportions. if atoms combine in simple whole number ratios, their proportions by mass must always be the same

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Law of Definite Proportions

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compounds composed of molecules

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molecular compounds

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compounds composed of cations & anions; usually composed of metal cations & nonmetal anions

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ionic compounds

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a chemical equation, which mass, is conserved; each side of the equation has the same number of atoms of each element

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balanced equation

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a chemical equation that does not indicate the relative amounts of reactants & products

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skeleton equation

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limits or determines the amount of product that can formed in a reaction

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limiting reagent

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reactant that is not completely used up in a reaction

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excess reagent

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is the ratio of the actual yield to the theoretical yiels; measures the efficiency of the reaction. should not be larger than 100%

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percent yield

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the optically transparent fusion product of inorganic material that have cooled to a rigid state without crystallizing

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glass

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the smallest group of particles within a crystal that retains the geometric shape of the crystal

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unit cell

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the forces that hold molecules together & are weak in liquids & covalent compopunds

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intermolecular forces

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kinetic energy is transferred without loss from one particle to another, and the total kinetic energy remains constant

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elastic collisions

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the amount of product that could form during a reaction calculated from a balanced chemical equation

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theoretical yield

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the amount of product that forms when a reaction is carried out in the lab

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actual yield

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state in which matter exist at very high temperatures involved in fusion, high-energy state in which ions exist in a gas like form. no known structural material can withstand the hot, corrosive condition of this state. magnetic fields are experiments in order to contain this state

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plasma