Across
- 4. Elements formed inside stars
- 7. Positively charged atom
- 8. Fundamental particle that makes up protons and neutrons
- 12. Cloud-like region where electrons are found
- 15. Unstable atoms that emit radiation
- 20. Process of forming elements inside stars
- 22. Anything that has mass and occupies space
- 24. Atoms that gain or lose electrons
- 25. Positively charged particle in the nucleus
- 26. The force that holds protons and neutrons together in the nucleus
- 27. Total number of protons and neutrons in an atom
- 28. Elements arranged by increasing atomic number
- 30. Energy released from splitting or fusing atomic nuclei
Down
- 1. Model that describes how electrons occupy energy levels
- 2. Vertical columns in the periodic table
- 3. Father of the modern periodic table (last name)
- 5. The building blocks formed after the Big Bang
- 6. Negatively charged particle in an atom
- 9. Process where two light nuclei combine to form a heavier one
- 10. The outermost electrons involved in bonding
- 11. Atoms of the same element with different numbers of neutrons
- 13. Splitting of a heavy atomic nucleus
- 14. Heaviest part of the atom, located at the center
- 16. Unit used to measure the mass of protons and neutrons
- 17. The number of protons in an atom
- 18. Basic unit of matter
- 19. Horizontal rows in the periodic table
- 21. Subatomic particle with no charge
- 23. Element with atomic number 92
- 29. Scientist who proposed an early atomic theory