Matter Review

3. discovered electrons
5. an atomic particle with a positive charge
6. a change in matter in which the substances that make up the matter change into other substances with new physical and chemical properties
12. a type of mixture that is evenly mixed
16. any of two or more atoms of the same element that have different numbers of neutrons
17. the smallest piece of an element that still represents the element
19. states that electrons can be found in the electron cloud
21. discovered the nucleus
22. describes elements that spontaneously emit radiation
24. the ability of one substance to dissolve in another
26. matter with a composition that is always the same
27. the mass per unit volume of a substance

1. Said, "Atoms are small solid objects that cannot be divided, created, or destroyed"
2. the sum of protons and neutrons
4. the process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
6. a substance that consists of two ore more different elements chemically bonded together
7. an atom that is no longer neutral because it has gained or lost electrons
8. the number of protons in an atom
9. a characteristic of matter that can be observed as it changes to a different type of matter
10. atomic mass/ the average mass of an element's isotopes, weighted according to the abundance of each isotope
11. a change in size, shape, form, or state of matter in which the identity stays the same
13. an atomic particle with a negative charge
14. a characteristic of matter that you can observe or measure without changing the identity of the matter
15. mixture/ a type of mixture that is unevenly mixed
18. credited with discovering neutrons and that they are neutral
20. anything that has mass and takes up space
23. to form a solution by mixing evenly
25. states that electrons orbit the nucleus
28. a neutral particle found in the nucleus of an atom