chap 16

3. the horizontal rows in the periodic table
5. area around the nucleus of an atom where its electrons are most likely found
7. particles with a negative 1 charge
10. neutral particles that have 0 charge
12. the weighted-average mass of the mixture of its isotopes
13. atoms of the same element that have different numbers of neutrons. (different mass numbers)
14. the number of protons in the element
15. protons and neutrons are made of even smaller particles called ......
16. particles that have 0 charge

1. the elements are arranged by increasing atomic number and by changes in physical and chemical properties
2. the vertical columns in the periodic table
4. small positively charged center of the atom. contains the protons and neutrons
6. particles with a positive 1 charge
8. uses the symbol of the element and dots to represent the electrons in the outer energy level
9. the smallest piece of matter that still retains the properties of the element
11. the sum of the protons and the neutrons in the element