In this video we take a look at what are elements, we discuss what makes elements different from one another and we cover the elements of the human body, and the percentage of each of these elements in the body. Elements of the human body Elements are substances that cannot be chemically broken down into simpler substances. There are over a hundred different elements, including oxygen and carbon. Elements differ based on the number of protons in their nucleus. The table of elements is shown on the screen, and each element is identified by its symbol and atomic number. For instance, carbon has the symbol C, and its atomic number is 6. The atomic number is the number of protons in its nucleus. This means that carbon atoms, and only carbon atoms have 6 protons in their nucleus. This bottom number is the atomic mass or mass number of a single carbon atom. It is equal to the number of protons, and the average number of neutrons in the nucleus. These brackets here signify a range for the atomic mass of carbon, because there are some carbon atoms that have different numbers of neutrons in their nucleus, these are called isotopes. There are many different elements that can have several different isotopes. There are a total of 26 elements that are present in the human body, and the material in the human body is made up of about 96% from 4 of these elements, oxygen, carbon, hydrogen and nitrogen. Of the 26 elements, 11 are considered to be major elements in the body, and they are the light blue colored elements in the table. The other 15 elements that are in the body are considered trace elements, and they are the peach colored elements in the table. The chart on the screen lists the major and trace elements in the body, along with their symbol and the percentage of body weight of each element. And that be the basics on elements and compounds of the human body.