52 terms

Chemistry Key Terms

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acid
substance that reacts with a base to form a neutral solution
atom
the smallest particle of matter
atomic number
the number of protons in the nucleus of each atom of any element
base
substance that reacts with acid to form a neutral solution
boiling point
the temperature at which a liquid changes to a gas
brittle
breaks or shatters easily
chemical change
change in which the composition or identity of matter changes
chemical equation
short form used for writing what happens in a chemical reaction
chemical formula
combination of chemical symbols and numbers indicating which elements and how many atoms of each are present in a molecule
chemical property
characteristic of a substance that cannot be changed without altering the sample
chemical reactivity
tendency of a substance to undergo a chemical change
chemical symbol
one to three letters that represent elements on the periodic table
chemistry
the branch of science that deals with the composition and properties of elemental forms of matter
compound
substance produced when two or more elements combine to produce a new substance with properties different from those of the original substances
conductor
substances that heat and electricity move through easily
density
the measure of the relative "heaviness" of objects with a constant volume; the mass of a given volume of a substance. (D=m/v)
ductile
ability to be drawn into wire
dull
not shiny
electron
negatively charged subatomic particle that moves around the nucleus of an atom
element
substance composed of one type of atom; pure substances that cannot be broken down into simpler substances
families
columns of elements on the periodic table with similar properties; also called groups
heterogeneous mixture
type of mixture where the substances are not evenly mixed
homogeneous mixture
type of mixture where two or more substances are evenly mixed on a molecular level but are not bonded together
indicator
substance that can be used to determine if a solution is an acid or base
law of conservation of matter
states that matter cannot be created or destroyed, it only changes form
litmus paper
an indicator that identifies if substances are acidic or basic
luster
having a shiny surface or reflecting light brightly
malleable
ability to be hammered or bent into different shapes
mass number
the number of protons plus the number of neutrons in the nucleus of an atom
matter
anything that has mass and takes up space
melting point
the temperature at which a solid can change to a liquid
metal
element that is malleable, ductile, a good conductor of heat and electricity, usually with a shiny or metallic luster; the largest group of elements on the periodic table, located on the left.
mixture
a combination of substances in which the individual substances keep their own properties without combining chemically
molecule
a particle formed when atoms share electrons, made up of 2 or more atoms
neutral solution
a solution with a pH of 7
neutron
uncharged subatomic particle in the nucleus of an atom
nonconductors
substance that does not easily allow heat or electricity to flow through it; insulator
nonmetal
element that is a poor conductor of heat and electricity, usually gases or brittle solids; the basis of the chemicals of life; located on the right side of the periodic table.
nucleus
positively charged cluster at the center of an atom containing the protons and neutrons
periodic table of the elements
chart of the chemical elements organized in rows according to increasing atomic number and columns according to the similarity of their chemical properties
periods
rows of elements on the periodic table
pH
measure of the acidity or alkalinity of a solution (how acidic or basic it is), usually measured on a scale of 0-14
pH paper
indicator paper that turns a series of colors to indicate acidic or basic tendencies of a substance
phenolphthalein
indicator that turns bright magenta in a strong base and clear in an acid
physical change
the form or appearance of matter changes, but not its composition
physical property
characteristic of a substance that can be observed or measured without altering a sample of the substance
precipitate
a solid that forms when two or more liquids are mixed
product
substance(s) that is formed as a result of a chemical reaction
proton
positively charged subatomic particle in the nucleus of an atom
reactant
substance(s) that exists before a chemical reaction begins
solution
a homogeneous mixture with substances evenly mixed throughout
substance
matter that has the same composition and properties throughout