Tham khảo sách 'chemistry part 11, julia burdge,2e (2009)', khoa học tự nhiên, hoá học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 240 CHAPTER 7 Electron Configuration and the Periodic Table all biological molecules. Carbon is perhaps the most versatile element because it has the ability to form various types of chemical bonds. Carbon atoms can form bonds to each other linking up to form an enormous variety of chains and ring structures. The metals play several different roles in living systems. As cations Na1 K Ca and Mg2 they serve to maintain the balance between intracellular and extracellular fluids nerve transmissions and other activities. They are also needed for protein functions. For example the Fe2 ion binds oxygen in hemoglobin molecules and Cu Zn and Mg2 ions are essential for enzyme activity. In addition calcium in the form of Ca5 PO4 3 OH and Ca3 PO4 2 is an essential component of teeth and bones. Essential elements in the human body 8A 18 1 2A 1 2 3A 13 4A 14 5A 15 6A 16 7A 17 1 2 B C N 0 F 2 3 Na Mg 3B 3 4B 4 5B 6B 6 7B 7 8 8B- 9 1 10 1 B 2B 1 12 Si P s Cl 3 4 ÎSk. Ca V Cr Mn Fe Co Ni C fo Zn Se 4 5 Mo I 5 6 6 7 7 Bulk elements Trace elements The periodic table shown highlights the essential elements in the human body. Of special interest are the trace elements such as iron Fe copper Cu zinc Zn iodine I cobalt Co selenium Se and fluorine F which together make up about percent of the body s mass. Although the trace elements are present in very small amounts they are crucial for our health. In many cases however their exact biological role is still not fully understood. These elements are necessary for biological functions such as growth the transport of oxygen for metabolism and defense against disease. There is a delicate balance in the amounts of these elements in our bodies. Too much or too little over an extended period of time can lead to serious illness retardation or even death. Checkpoint Development of the Periodic Table Which of the following elements would you expect to have chemical properties most similar to those of S Which of the following elements .
