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40 Cards in this Set

  • Front
  • Back
systematic observations or measurements, preferably made under controlled conditions
tentative explanations for scientific observations
verbal or mathematical descriptions of a phenomenon that allows for general predictions. A law says what happens, not why it happens
statements that attempt to explain why nature behaves the way it does. They tend to be incomplete and imperfect, evoloving with time to explain new facts as they are discovered
scientific method
the procedure scientists use to search for answers to questions and solutions to problems
the quantity of matter an object contains: mass is a fundamental property of an object that does not depend on its location
one of the three disinct states of matter under normal conditions, gases have neither fixed shapes nor fixed volumes and expand to fill their containers completely
liquids have a fixed volume but flow to assume the shape of their containers
solids are relatively rigid and have fixed states and volumes
a combination of two or more pure sustances in variable proportions in which the individual substances retain their identities
homogenous mixture
a mixture in which all portions of the material are in the same state, have no visible boundaries and are uniform throughout (koolaid)
heterogeneous mixture
a mixture in which a marterial is not completely uniform (chocolate chip cookies)
a pure substance that cannot be broken down into simpler ones by chemical changes
physical properties
a characteristic that scientists can measure without changing the composition of the sample under study (mass, color, volume)
chemical properties
the characteristic ability of a substance to react to form new substances
intensive property
a physical property that does not depend on the amount of the substance (color, boiling point, melting point)
extensive property
a physical property that varies with the amount of the sustance (mass, weight, volume)
mass/volume an intensive property of matter, mass per unit volume
the fundamental, indivisible particles of which matter is composed
a subatomic particle with a negative charge
the central core of an atom, where protons and any neutrons reside, comprises most of the mass of an atom but very little volume
positive charge, opposite of the electron
the spontaneous emission of energy rays by matter
atomic number
(z) the number of protons in the nucleus of an atom of an element, the atomic number is different for each element
atoms that have the same number of protons and hence the same atomic number (Z) but different numbers of neutrons
mass number
(A) the number of protons and neutrons in the nucleus of an atom of an element. Isotopes in an element only differ in their atomic mass
atomic mass unit
(amu) 1/12 of the mass of one atom of 12C
a charged particle produced when one or more electrons is removed from or added to an atom or molecule
periodic table
a chart of the chemical elements arranged in rows of increasing atomic number so that the elements in each column (group) have similar chemical properties
any of the vertical columns of elements in the periodic table
the rows of elements in the periodic table
alkali metals
any of the elements in group 1 of the periodic table. All are metals that react readily with nonmetals to give ions with a +1 charge
alkaline earths
the elemeents in group 2 of the periodic table that all react readily with nonmetals to give ions a +2 charge
noble gases
any of the elements in group 18 of the periodic table that are all unreactive monatomic gases at room temperature and pressure
any of the elements in group 17 that all react readily with metals to give ions with a -1 charge
any of the elements to the left of the zigzag line in the periodic table, can be hammered into thin sheets, pulled into wires, most are shiny, all except mercury are solids at room temperature
any of the elements to the right of the zigzag line, poor conductors of electricity, not shiny, not malleable, not ductible
have properties between those of metals and nonmetals
main group elements
any of the elements in groups 1, 2 and 13-18
essential element
any of the 19 elements that are absolutely required in the diets of humans in order for them to survive