hi everyone and welcome to biology professor today we're talking about trace elements now if you would like a better understanding of what elements are please see my other video titled elements vs. compounds now to understand what trace elements are first let's talk briefly about common elements the most common elements among living organisms are carbon oxygen hydrogen and nitrogen in fact these four elements alone are so common that they make up approximately 96% of all living matter so now that we know what common elements are lower trace elements well depending on whether you are coming at this from a biology perspective or a chemistry perspective trace elements has a slightly different definition from the biology side of things a trace element is a dietary element so something that an organism obtains as a nutrient source a dietary element needed in very small quantities these are elements that are essential for the organism to grow to develop and to have overall everyday healthy physiology these include elements like iodine iron copper zinc and others and you've probably heard of these elements especially if you're taking a daily multivitamin for example some elements are even added to our food sources for example iodized salt is table salt that contains iodine in order to make sure that humans are eating the necessary amounts of iodine in their diet now if you're looking at trace elements from a chemistry perspective the definition is still somewhat alarm in chemistry a trace element is an element found again in very small concentrations in some sample so still we have this situation where it's a very small part of the overall sample in general in chemistry the sample in order for it to be considered a trace element it needs to be present at concentrations of less than 100 parts per million for example but that is it today for trace elements thanks for watching biology professor and I hope you learned a lot