chemistry exam vocab 2
Terms
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- the study of the structure, properties, and composition of substances & the changes they undergo
- chemistry
- a substance that cant be changed into simpler substances under normal lab conditions
- element
- a purification process in which a liquid is evaporated & then condensed again to a liquid
- distillation
- a carefully controlled & repeatable procedure for gathering data to test a hypothesis
- experiment
- matter that has no definite shape or volume; takes the shape of the container
- gas
- a proposed explanation for observations
- hypothesis
- a substance formed in a chemical reaction
- product
- a substance in the gaseous state that is ordinarily a liquid or solid at room temperature
- vapor
- a substance that can be separated into simpler substances by chemical reactions
- compound
- a starting substance in a chemical reaction
- reactant
- a concise statement that summarizes the results of many observations & experiments
- scientific law
- explains observations
- scientific theory
- a mixture that is not uniform in composition
- heterogeneous mixture
- a mixture that is completely uniform in composition
- homogeneous mixture
- states that mass can neither be created nor destroyed in an ordinary chemical or physical process
- law of conservation of mass
- a form of matter that flows, has a fixed volume, and takes the shape of its container
- liquid
- the amount of matter that an object contains
- mass
- anything that has mass and takes up space
- matter
- ionized gas
- plasma
- a physical blend of 2 or more substances that are not chemically combined
- mixture
- changes the form of an object but doesnt change compostion
- physical change
- a method of inquiry involving observation, experiments, hypotheses, & broad explanations called theories
- scientific method
- matter that has definite shape and volume
- solid
- a homogeneous mixture
- solution
- a sample of matter having a uniform and definite composition
- substance
- the changing of substances to other substances by the breaking of bonds in reactants & the formation of bonds in products
- chemical reaction
- atoms are converted into another compound; not usually reversible
- chemical change
- a quality of a substance that can be observed or measured without changing the substances chemical composition
- physical property
- the ability of a substance to undergo chemical reactions & to form new substances
- chemical property
- the closeness of a measurement to the true value of what is being measured
- accuracy
- measurements with a combination of units
- derived units
- describes the closeness of a set of measurements taken under the same conditions
- precision
- the ratio of the mass of an object to its volume
- density
- the zero point on the kelvin temperature scale, equivalent to -273.15 degrees celcius
- absolute zero
- the temperature scale in which the freezing point of water is 273 & the boiling point is 373
- kelvin
- the % that a measured value differs from the accepted value
- percent error
- expression of numbers in the form nX10^n where n is equal to or greater than 1 or less than 10 & n is an integer
- scientific notation
- a measure of the average kinetic energy of particles in matter
- temperature
- the space occupied by a sample of matter
- volume
- force that measures the pull of gravity on a given mass
- weight
- the SI unit for mass
- kilogram
- the smallest particle of an element that retains the properties of that element
- atom
- atom or group of atoms with a negative charge
- anion
- in any sample of a chemical compound, the elements are always combined in the same proportion by mass
- law of definite proportions
- the number of protons in the nucleus of an atom of an element
- atomic number
- a unit of mass equal to one-twelth the mass of a carbon-12 atom
- atomic mass unit
- atoms of the same element that have the same atomic number but different atomic masses due to a different number neutrons
- isotopes
- a stream of electrons produced at the negative electrode [cathode] of a tube containing a gas at low pressure
- cathode ray (vacuum tube)
- a negatively charged subatomic particle
- electron
- a subatomic particle with no charge & a mass of 1 amu: found in the nucleus of the atom
- neutron
- a positively charged subatomic particle found in the nucleus of an atom
- proton
- the dense central portion of an atom, composed of protons & neutrons
- nucleus
- the total number of protons & neutrons in the nucleus of an atom
- mass number
- any atom or group of atoms with a positive charge
- cation
- a horizontal row of elements in the periodic table
- period
- the lowest whole number ratio of ions in an ionic compound
- formula unit
- the vertical column of elements in the periodic table
- group
- a compound that produces hydrogen ions in solution, is a hydrogen-ion donor, or an electron-pair acceptor
- acid
- a tightly bound group of atoms that behaves as a unit & carries a charge
- polyatomic ion
- group B element charaterized by addition of electrons to d suborbitals
- transition metal
- one of the classes of elements that includes a large majority of their known elements
- metal
- one of a class of elements having properties intermediate to metals and nonmetals
- metalloid
- one of a class of elements that are not lustrous & are generally poor conductors of heat & electricity
- nonmetal
- a chemical formula that shows the actual number & kind of atoms present in a molecule of a compound
- molecular formula
- a compound that is composed of molecules
- molecular compound
- a formula with the lowest whole number ratio of elements in a compound
- empirical formula
- a compuond composed of + & - ions
- ionic compound
- an arrangement of elements into rows & columns according to similarities in their properties
- periodic table
- group A elements on the periodic table
- representative element
- a compound containing atoms of 3 different elements, usually containing at least one polyatomic ion
- ternary compound
- a compound composed of 2 elements
- binary compound
- a table listing metals in order of decreasing activity
- activity series of metals
- vaporization that occurs at the surface of a liquid that is not boiling
- evaporation
- that portion of chemistry dealing with numerical relationships in chemical reactions; the calculation of quantities of shubstances involved in chemical equations
- stoichiometry
- the amount of a substance that contains 6.02X10^23 representative particles of that substance
- mole
- any reactant that is used up first in a chemical reaction
- limiting reagent
- the conversion of a solid to a gas or vapor without passing through the liquid state
- sublimation
- 1 of 2 or more different molecular forms of an element in the same physical state
- allotrope
- a term used to describe a solid that lacks an ordered internal structure; denotes a random arrangement of atoms
- amorphous solid
- a substance that increases the rate of reaction by lowering the activation-energy barrier
- catalyst
- a substance in which the atoms, ions, or molecules are arranged in an orderly, repeating, & dimensional pattern
- crystal
- the energy an object has because of its motion
- kinetic energy
- an instrument used to measure atmospheric pressure
- barometer