Terms – Chemistry Flashcard

Scientific Law
A concise statement that summarizes the results of many observations and experiments
Homogeneous
A mixture in which the composition is uniform throughout
Heterogeneous
A mixture which composition is not uniform throughout
Mixture
A physical blend of two or more components
Hypothesis
A proposed explanation for an observation
Reactant
A substance present at the start of a reaction
Product
A substance produced in a reaction
Catalyst
A substance that increases the rate of reaction by lowering the activation-energy barrier; the catalyst is not used up in the reaction
Doberman’s triads
Groups of 3 elements with similar properties
Compound
Is a substance that contains two or more elements chemically combined in fixed proportion
Specific Gravity
Is the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure
Density
Is the ratio of the mass of an object to its volume
Element
Is the simplest form of matter that has a unique set of properties
(pure) Substance
Matter that has a uniform and definite composition
Avogrado’s Hyptothesis
States that equal volumes of gases measured at the same temperature and pressure contain the same numbers of particles
The law of definite proportion
states that in samples of any chemical compound, the masses of the elements are always in the same proportions
Responding or dependent variable
The variable that is observed during the experiment
Manipulated or independent variable
The variable that you change in an experiment
Absolute Zero
The zero point of the kelvin scale is 0k
Theory
Well-tested explanation for a broad set of observations
Periodic Law
When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties
The law of multiple proportions
whenever the same two elements form more than

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