Across
- 1. The new substances that are formed during a chemical reaction
- 6. What Alfred Nobel invented
- 7. Number of electrons the first shell can hold
- 9. What takes place when the bonds between atoms are broken and new bonds are formed, creating a new arrangement of atoms and at least one new substance.
- 10. The law of … which states that matter can be neither created nor destroyed during a chemical reaction.
- 12. An atom with a different number of protons and neutrons
- 15. Complete the equation: methane + oxygen —> _____ ______ + water
- 16. The number that tells you how many molecules are in an equation
- 20. An ion with a negative charge
- 21. A charged atom
- 22. Chemical reactions that absorb energy from their surroundings
- 23. The protons and neutrons in an atom make up the _____
- 24. The number that tells you how many atoms are in a molecule
- 27. The substance that reacts with oxygen in a combustion reaction
- 28. Complete the equation: hydrogen + _____ —> water
Down
- 2. The number that tells you the charge of an ion
- 3. Reactions in which a substance reacts with oxygen and heat is released
- 4. The law of ... which states that a compound, no matter how it is formed, always contains the same relative amounts of each element.
- 5. The number of protons on an atom. Determines the element
- 8. The original substances in a chemical reaction
- 11. An ion with a positive charge
- 13. Chemical reactions that release energy
- 14. The ability to do work
- 17. Combustion reactions are examples of ______ reactions
- 18. Element represented by the letter K
- 19. A change of state is an example of a _____ change
- 25. All chemical equations need to be _______
- 26. The shell which can hold up to 18 electrons