modified from: Holt Science & Technology Grade 8 Tennessee

compound

substance made up of atoms of two or more different elements joined by chemical bonds

density

ratio of the mass of a substance to the volume of the substance

element

substance that cannot be separated or broken down into simpler substances by chemical means

law of conservation of mass

law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

nucleus

an atom's central region, which is made up of protons and neutrons

pH

value that is used to express the acidity or basicity (alkalinity) of a system

product

substance that forms in a chemical reaction

reactant

substance or molecule that exists before a chemical reaction

relative age

approximate age of fossils or other objects in rock layers determined by comparing whether the surrounding rock layers are younger or older

volume

measure of the size of a body or region in three dimensional space

weight

measure of the gravitational force exerted on an object

atom

smallest particle that makes up all types of matter

adaptive technology

device or product that has been changed in some way to better help someone, special version of an already existing product

assistive technology

device, product, or service that has been developed to help someone

adaptation

any variation that makes an organism better suited for their environment

mass

amount of matter in an object

gravity

force that exists between any two objects that have mass

chemical change

change in which the composition of a substance changes

physical change

change in which the form or appearance of matter changes, but not its composition

gas

matter that does not have a definite shape or volume; has particles that move at high speeds in all directions

liquid

matter with a definite volume but no definite shape that can flow or slide from one place to another

solid

matter with a definite shape and volume; has tightly packed particles that move mainly by vibrating

graduated cylinder

tool used to measure the volume of liquids

balance

tool used to measure mass

scale

tool used to measure force

dependent variable

variable that changes as a result of a change in the experimental variable

independent variable

variable that the experimenter changes

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