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physscience
2nd test
Question | Answer |
---|---|
matter | |
a substance that cannot be sepereated or broken down | element |
the smallest unit of an element | atom |
group of atoms that are held together by chemical forces | molecule |
the amount of matter in an object and how compact it is | density |
the change in the physical properties of a substance, such as size or shape | physical change |
an irreversible change in the atoms of an object | chemical change |
what is the atomic number for hydrogen | 1 |
what is the atomic number for helium | 2 |
what is a mixture? | a combination of two things that are not chemically combined |
what is a pure substance? | matter that is either a single element or a single compound |
what is a compound | made up of atoms of two or more elements joined chemically |