This is a list of the key ideas in this lesson. Click on any one you want to explore. Once in the Net, move by clicking on any boldface word.

1	periodic table	2	element	3	atom
4	carbon atom	5	hydrogen atom	6	nitrogen atom
7	oxygen atom	8	phosphorus atom	9	sulfur atom
10	living things	11	2 covalent bonds	12	nucleic acids
13	carbohydrates	14	lipids	15	proteins
16	oxygen gas	17	molecule	18	hydrogen gas
19	atomic number	20	atomic weight	21	ion
22	positively charged ion	23	negatively charged ion	24	isotope
25	oxygen 15	26	oxygen 17	27	oxygen 18
28	hydrogen bond	29	bond	30	ionic bond
31	covalent bond	32	organic molecule	33	matter
34	molecular weight