Ch 2 - Crossword Labs

2. Covalent Bond a covalent bond where electrons are shared equally between atoms.
3. a negatively charged ion.
5. the smallest unit of an element, which keeps the properties of that element.
6. Number the number of protons in an atom's nucleus, which identifies the element.
9. Bond a strong chemical bond formed when atoms share electrons.
10. Elements elements that organisms need in very small amounts.
12. Bond a chemical bond formed by the electrical attraction between a cation and an anion.
15. Elements chemicals an organism needs to live and reproduce.
16. a chemical reaction that proceeds in only one direction and cannot be easily undone.
19. Covalent Bond a covalent bond where electrons are shared unequally, creating a slight positive and negative end.
20. particles in an atom's nucleus that have no electrical charge.
21. Bond a weak bond between a hydrogen atom (that's already part of a polar molecule) and a more electronegative atom in another molecule.
23. Reactions processes that change one set of chemicals into another.
24. atoms or molecules that have a net electrical charge due to a loss or gain of electrons.

1. the starting chemicals in a chemical reaction.
4. the four elements that make up 96% of living matter: ___________, oxygen, hydrogen, and nitrogen.
6. Mass the average mass of an atom, roughly the sum of protons and neutrons.
7. anything that takes up space and has mass.
8. a chemical reaction that can proceed in both the forward and reverse directions.
11. particles in an atom's nucleus that have a positive electrical charge.
13. a substance made of only one type of atom that can't be broken down further.
14. particles orbiting an atom's nucleus that have a negative electrical charge.
17. Electrons electrons in the outermost shell of an atom, which are involved in chemical bonding.
18. the new substances formed by a chemical reaction.
22. Mass the sum of the atomic masses of all the atoms in a molecule.
23. a positively charged ion.