gabi r icp

2. protons and neutrons are made of even smaller particles
4. atoms of the same element that have different numbers of neutrons. (different mass numbers)
6. small positively charged center of the atom. contains the protons and neutrons
7. the vertical columns in the periodic table
10. particles with a positive 1 charge
12. the number of protons in the element
14. uses the symbol of the element and dots to represent the electrons in the outer energy level
15. area around the nucleus of an atom where its electrons are most likely found

1. the sum of the protons and the neutrons in the element
3. the weighted-average mass of the mixture of its isotopes
5. the elements are arranged by increasing atomic number and by changes in physical and chemical properties
8. neutral particles that have 0 charge
9. the smallest piece of matter that still retains the properties of the element
11. particles with a negative 1 charge
13. the horizontal rows in the periodic table