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Physics 2.3
Composition of matter
| Term | Definition |
|---|---|
| Atom | Basic building blocks of all matter |
| Nucleus | Dense central core of an atom, has protons and neutrons |
| The three subatomic particles | Protons, Neutrons, Electrons |
| Atomic number | Number of protons in an atom |
| Atomic mass | Average mass of all isotopes in an element |
| Mass number | Total number of protons and neutrons in the nucleus |
| Ion | Atom that is electrically charged due to gaining or losing electrons |
| Element | Substance that can’t be broken down |
| Isotope | Atoms that have the same atomic number but different mass numbers |
| Periods | rows of elements that have the same number of electron shells around the nucleus |
| Groups | columns of elements that have the same number of valence electrons |
| The identity of an element is based on the ____ in an atom | protons |