Atomic Theory Vocabulary

4. particle two protons and two neutrons (a helium ion) emitted during fission
7. particle electron emitted during fission
9. an isotope of hydrogen with one proton and two neutrons in the nucleus having a mass number of 3
12. A pure substance made of only one kind of atom
13. The Nuclei of two atoms combine to create a new atom
14. atomic nucleus splits and releases lots of energy
16. change when elements change into different elements because the number of protons has changed
17. Mass Average mass of all the known isotopes of an element
20. Made up of protons and neutrons; Center of an atom
22. most common hydrogen isotope; has one proton and no neutrons so the mass number is 1
23. ray ray of energy emitted during fission
24. A charged atom created by gaining or losing electrons

1. Atoms of one element that have different numbers of neutrons
2. negatively charged subatomic particle; located in the electron cloud; mass of basically nothing
3. of ion # of protons - # of electrons
5. Basic unit of matter; Smallest particle of an element
6. neutrally charged subatomic particle; located in the nucleus; mass of 1 a.m.u.
8. positively charged subatomic particle; located in the nucleus; mass of 1 a.m.u
10. An isotope of hydrogen with one proton and one neutron in the nucleus having a mass number of 2
11. A negatively charged ion
15. nuclear force force that holds the nucleus (protons and neutrons) together
18. Number The sum of protons and neutrons in an atom's nucleus
19. number Number of protons; identifies the element
21. A positively charged ion