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Across 1. 3d region around a nucleus that indicates the probable location of an electron 4. a fundamental property of an object generally regarded as equivalent to the amount of matter in the object 5. in an atom, the core of protons and neutrons; in a eukaryotic cell, the organelle that contains most of the DNA and directs most of the cell’s activities 6. a chemical attachment between atoms 12. a substance that ordinarily cannot be broken down chemically to form simpler kinds of matter 13. total numbers of protons and neutrons of an atom 14. anything that occupies space and has mass 15. a subatomic particle with no electric charge 16. a particle with a negative electric charge that orbits the nucleus of an atom 17. a bond formed by electrical attraction between two oppositely charged ions

Down 2. an atom or molecule with an electrical charge 3. the number of protons in an atom 4. a chemical structure composed of one or more atoms 7. a bond that forms when two atoms share one or more pairs of electrons 8. the simplest particle of an element that retains all the properties of that element 9. a subatomic particle with a positive charge 10. a pure substance that is made up of atoms from two or more elements 11. atoms of the same element that have a different number of neutrons