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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 |