Physical Science Ch. 16

3. Particle of matter that makes up protons and neutrons
5. Group 2A is known as the ________.
7. Number of protons in an atom's nucleus
8. Particle in the nucleus with an electric charge of 1+
11. Area around the nucleus of an atom where the atom's electrons are most likely found
12. Located to the left of the stair-step ladder
14. The horizontal row on the periodic table; represent the energy levels
15. Located along the stair-step ladder
16. An atom of an element that has a specific number of neutrons
17. Group 7A is known as the ________.
19. The smallest particle of an element that still retains the properties of the element
21. The sum of the number of protons and neutrons in an atom's nucleus
22. Electrically neutral particle inside the nucleus of an atom

1. Particle with an electric charge of 1- and surrounds the nucleus of an atom
2. The small positively charged center of an atom that contains both protons and neutrons
4. Organized list of all known elements that are arranged by increasing atomic number and by changes in chemical and physical properties
6. Uses the symbol for an element and dots representing the number of electrons in the element's outer energy level
9. Group 8A is known as the ________.
10. Weighted-average mass of an element's isotopes according to their natural abundance
13. Vertical column in the periodic table
18. Group 1A is known as the ________.
20. Located to the right of the stair-step ladder