In this video, we're going to begin our lesson on the elements of life. It's interesting to note that of all the known elements in the universe, only a small subset of these is found in living organisms. The periodic table of elements, which you've probably seen before in some of your previous courses, actually arranges all of the known elements based on their chemical properties. If we take a look at our image down below, you'll be able to see all of the known elements in the periodic table. Once again, living organisms do not utilize all of these elements; they only utilize a small subset. In fact, 97% of the mass of most living organisms is composed of just 6 elements, and those 6 elements are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. If you take the chemical symbol of those 6 elements, which is really just the first letter of those 6 elements, you can spell the word CHNOPS. This mnemonic is a helpful way to remember the 6 most abundant elements that make up most living organisms. We also refer to these 6 elements as the bulk elements. You'll notice that here in blue, we're labeling the blue boxes within the periodic table as the bulk elements. The bulk elements are very abundant within living organisms. Again, those elements include hydrogen, carbon, nitrogen, oxygen, phosphorus, and sulfur. If you use these elements, you can spell the word CHNOPS, which can be very helpful to remember the bulk elements.
Although these six elements make up the vast majority of the mass of most living things, there are some trace elements as well. Trace elements are those that are required for life but are needed in very small amounts. Whereas the bulk elements are found in large amounts, the trace elements are found in very small amounts. Notice that in our image down below, the trace elements are in yellow boxes. Once again, these trace elements are necessary for life, but they are only required in very small amounts. You'll see all of these yellow-highlighted boxes here are part of the trace elements. There's no need for you to memorize all of these trace elements; instead, you should just be aware of the fact that there are trace elements required for life in small amounts and you should be more aware of the fact that the bulk elements are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur and CHNOPS can help you remember that. This concludes our brief introduction to the elements of life, and we'll be able to get some practice applying these concepts as we move forward. So, I'll see you all in our next video.