BIO CH. 2 CROSSWORD

2. Protons and electrons are negatively _____
6. A starting mateiral in a chemical reaction.
7. Compound consisting of hydrogen and oxygen in a 2:1 ratio
9. Chemical ____ is when in a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction.
10. The number of protons is called the ____ number
12. ___ electrons are the electrons in the outermost shell.
14. Smallest unit of matter
16. Different atomic forms of the same element are called _____
17. The attraction of an atom for the electrons of a covalent bond.
18. A measure of mass for atoms and subatomic particles.
19. An ending material in a chemical reaction.

1. Two or more atoms held together by covalent bonds.
3. ____ elements are required by an organism in only minute quantities.
4. What are all organisms composed of?
5. A ____ reaction is a process leading to chemical changes in matter; involves the making and/or breaking of chemical bonds.
8. Substance that cannot be broken down.
11. An atom that has gained or lost electrons, thus acquiring a charge.
13. Substance containing 2 or more elements.
15. A ____ bond is a type of strong chemical bond in which two atoms share one pair of valence electrons.
17. The capacity to cause change.