Atom
the basic building blocks of all matter
atomic mass
the number of protons plus the number of neutrons in the nucleus of an atom
atomic number
the number of protons in the nucleus of an atom
Boiling point
the temperature at which a liquid vaporizes and changes into a gas
Chemical change
occurs when a substance is changed into a new substance with different properties
chemical fomula
code that uses chemical symbols and subscripts to identify the number and type of atom of each element to make a compound
Chemical properties
characteristic that describes how a substance will interact with other substances during a chemical reaction
Chemical reaction
process where one or more substances undergo change to produce a new substance
chemical symbol
a one or two-letter code that represents an element
coefficient
a number written before a chemical formula to show how many molecules of a compound are present
Combustibility
the ability to used as fuel to burn
Compound
a pure substance that forms when two or more elements join chemically
condensation
the changing of a substance from a gas to a liquid
Conduction
the transfer of heat by direct contact of particles
Convection
the transfer of heat in fluids by the movement of currents that form in the fluids
Density
physical property that compares the mass of a substance per unit volume
Dilute
to reduce the concentration or intensity
Dissolve
when a solid becomes incorporated into a liquid to form a solution
electron
part of an atom with a negative charge that spins around the nucleus
Element
pure substance that cannot be broken down into simpler substances by any ordinary chemical means
Gas state
a substance that has neither a definite shape nor a definite volume
group
the vertical (up & down) column in the periodic table
Heat
the transfer of thermal energy between two objects at different temperatures
Kinetic energy
energy resulting from the motion of an object
Law of Conservation of Energy
energy is neither created nor destroyed, but may be changed from one form to another
Law of Conservation of Matter
during a chemical reaction, matter cannot be created or destroyed; it will only change from one form to another
Liquid state
substance that has a definite volume but no definite shape
Mass
measure of the amount of matter making up an object
Matter
anything that has volume and mass
Melting point
temperature at which a substance changes from a solid to a liquid
metal
elements found on the left side of the periodic table that tend to be shiny and good conductors of heat and electricity
metalloid
elements with properties of both metals and nonmetals (found along the zig zag on periodic table)
Mixture
type of matter that forms when two or more substances combine without joining together chemically
Molecule
two or more atoms that are bonded together chemically; smallest unit of a compound that has all the properties of the compound
neutron
part of an atom with no charge found in the nucleus
nonmetal
elements found on the right side of the periodic table that are poor conductors of heat and electricity
nucleus
center of an atom; made of protons and neutrons
period
horizontal row in the periodic table
periodic table
chart that organizes information about all of the known elements according to their properties
Physical change
a change that affects one or more physical properties of a sustance
Physical properties
characteristic that can be observed or measured without changing the identity of a substance
Plasma state
state of matter that forms when temperatures are high enough to completely remove electrons from the atoms to which they were bound (ex: sun)
Potential energy
stored energy
Precipitate
a solid that forms from a chemical reaction that takes place in a solution
product
the subtance that remains after a chemical reaction takes place
proton
part of an atom that carries a positive charge; found in the nucleus
pure substance
substance that is the same throughout that cannot be broken down or separated using physical means
Radiation
the transfer of heat without matter; heat than can travel through empty space
reactant
substances before a reaction occurs
Reactivity
describes how likely an element is to form bonds with other elements
Solid state
substance with a definite shape and volume
Solubility
the ability to dissolve in another substance
Solute
the substance that is dissolved to form a solution
Solvent
the substance in which a solute is dissolved to form a solution
state of matter
physical form in which matter exists; phase
sublimation
phase change directly from a solid to a gas without turning into a liquid
subscript
small number written in a chemical formula to tell the number of atoms of that element
valence electrons
electrons located in the outermost energy level of an atom
vaporization
process in which a liquid changes to a gas
Volume
the amount of space matter occupies