WEBVTT 00:00:03.002 --> 00:00:05.867 We Humans have known for thousands of years, just looking at our environment around us that 00:00:07.207 --> 00:00:10.333 there are different substances, and these different substances tend to have different properties, and 00:00:11.954 --> 00:00:14.745 not only do they have different properties; one might reflect light in a certain way, or not reflect light NOTE Paragraph 00:00:17.601 --> 00:00:20.457 or be a certain colour, or at certain temperature be liquid, or gas, or be a solid, 00:00:22.108 --> 00:00:24.867 but we also start to observe how they react with each other in certain circumstances. 00:00:27.663 --> 00:00:31.477 And here's pictures of some of these substances. This right here is Carbon, and this is in it's graphite form; 00:00:31.477 --> 00:00:36.069 this right here is Lead, this right here is Gold, 00:00:38.719 --> 00:00:41.369 and all of the ones that I've drawn, that I've shown pictures of here, and I got them all from this website right over there 00:00:41.369 --> 00:00:45.453 all of these are in their solid form, but we also know that 00:00:47.395 --> 00:00:49.338 it looks like there's certain types of air, you know, certain types of air particles, 00:00:49.338 --> 00:00:52.210 and depending on what type of air particles you're looking at 00:00:55.079 --> 00:00:57.948 whether it is carbon, or oxygen, or nitrogen, that seems to have different types of properties, 00:00:57.948 --> 00:00:59.425 or there are other things that can be liquid, 00:00:59.425 --> 00:01:02.082 or even if you raise the temperature high enough on these things, 00:01:02.082 --> 00:01:05.018 if you raise the temperature high enough on Gold or Lead 00:01:05.018 --> 00:01:06.503 you could get a liquid, 00:01:06.503 --> 00:01:09.841 Or if you kind of - if you burn this Carbon 00:01:09.841 --> 00:01:12.076 you can get it to a gaseous state, 00:01:12.076 --> 00:01:13.351 you can release it into the atmosphere,