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B2 Ch 3 Lesson 1
Intro to Atoms
Term | Definition |
---|---|
Element | A pure substance that cannot be broken down into any other substances by chemical or physical means. |
Molecule | A group of two or more atoms held together by chemical bonds. |
Atom | The basic particle from which all elements are made; the smallest particle of an element that has the properties of that element. |
Electron | A tiny, negatively charged particle that moves around the outside of the nucleus of an atom. |
Nucleus | The central core of an atom which contains protons and neutrons. |
Proton | Small, positively charged particles that are found in the nucleus of an atom. |
Energy Level | A region of the atom in which electrons of the same energy are likely to be found. |
Neutron | A small particle in the nucleus of the atom, with no electrical charge. |
Atomic Number | The number of protons in the nucleus of an atom. |
Isotopes | An atom with the same number of protons and a different number of neutrons from other atoms of the same element. |
Mass Number | The sum of protons and neutrons in the nucleus of an atom. |