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Across 7. electrolytes that release ions that bond with hydrogen ion. 8. the number of protons & neutrons in an element 10. when atoms of two different elements bond 11. the number of protons in an element 12. atoms that gain or lose electrons 15. an uneven distribution of charges 16. electrolytes that release hydrogen ions 18. the smallest complete units of elements 19. the way atoms interact with one another forming bonds 20. the bonding of two or more atoms forming a new particle 21. atoms with the same atomic number but different atomic weights

Down 1. speed up a chemical reaction 2. represents the numbers & types of atoms in a molecule 3. when two or more atoms bond to form a more complex structure 4. branch of science that considers the composition of matter & how it changes 5. when bonds within a reactant molecule break so that simpler molecules, atoms, or ions form. 6. and equal sharing of electrons between elements 9. requires much of the energy that cells require. 13. made up of carbon 14. oppositely charged ions that attract and form a chemical bond 17. all matter is composed of this