Across
- 3. - the weighted-average mass of the mixture of its isotopes
- 6. - protons and neutrons are made of even smaller particles
- 7. cloud - area around the nucleus of an atom where its electrons are most likely found
- 9. - the elements are arranged by increasing atomic number and by changes in physical and chemical properties
- 11. - the number of protons in the element
- 13. - neutral particles that have 0 charge
- 14. - the vertical columns in the periodic table
- 15. - the smallest piece of matter that still retains the properties of the element
Down
- 1. - small positively charged center of the atom. contains the protons and neutrons
- 2. - the sum of the protons and the neutrons in the element
- 4. - particles with a negative 1 charge
- 5. - uses the symbol of the element and dots to represent the electrons in the outer energy level
- 8. - particles with a positive 1 charge
- 10. - the horizontal rows in the periodic table
- 12. - atoms of the same element that have different numbers of neutrons.