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  1. 1. lements E
  2. 2. Basic Competence Students are able to to explain the definition of element and compound.
  3. 3. What are elements? Elements are pure substances (like hydrogen and oxygen) that can’t be split into simpler substances by chemical or physical means. Some common examples of elements are hydrogen, nitrogen, and carbon. In total, 118 elements have been observed. New elements are discovered from time to time by artificial nuclear reactions. ELEMENTS
  4. 4. Who disc vered elements? ELEMENTS As i have stated before, the Greek, Hindu, and Japanese came up with 4 main classical elements. In 1661 Robert Boyle showed that there were more than just 4 classical elements. The first modern list of chemical elements was given in Antoine Lavoisier's 1789 Elements of Chemistry, which contained thirty-three elements. In 1869, medeleev’s periodic table showed 66 elements. As the Years went by, more and more elements were discovered, up until now, there are 118 elements. Robert Boyle Mendeleev
  5. 5. ELEMENTS 2006 version :: 116 elements The periodic table of elements
  6. 6. ELEMENTS 2008 version :: 118 elements The periodic table of elements
  7. 7. ELEMENTS Atomic number As you’ve seen in the tables earlier, there is a number next to the element. But what does this mean? The number is called the atomic number, which is determined by the number of protons in an element. For example, carbon has 6 protons, so its atomic number is 6. Atomic mass The atomic mass is the number of nucleons In the atomic nucleus.
  8. 8. ELEMENTS Classical elements Many ancient philosophies used classical elements to explain patterns in nature The Greek, Hindu, and Japanese shared the same classical elements, which were Earth, Water, Air, Fire, and Aether The fifth element, was used to describe that which was beyond the material in this world.
  9. 9. ELEMENTS What do we use elements for? On the other hand . . . We use elements to construct thousands of things. And we need those things, such as steel for our everyday necessities. Without iron, nickel, manganese, and many more, we would be missing many types of steel. A laser, useable in many areas of life.
  10. 10. ELEMENTS What do we use elements for? On the other hand, there are some elements such as plutonium, uranium, and more that are used to destroy. Atomic Bomb 1945
  11. 11. ELEMENTS Radioactivity Again, this all relates back to elements, as radioactivity would not be possible without elements. Benefits: Radioactivity is often used to diagnose and treat diseases. It can also produce energy for heat and electric power, and kill microorganisms that cause contamination and disease. Disadvantages: Is extremely harmful, and just a small dose will kill you. This just proves my point about elements, that NOTHING could be possible without them.
  12. 12. Q&A You can look but you better not touch Plutonium . This emits alpha radiation. The radiation from even a small amount of plutonium gas will give you lung cancer. Mercury . This evaporates readily at room temperature, and is highly poisonous. It can cause brain damage. Lead . This stuff is put in the air by burning and fueling with leaded gasoline, and it appears in old paint. This can cause brain damage, especially for younger children. What are some elements that are dangerous? Q: A:
  13. 13. ELEMENTS Isotope Symbols Example: H 2 O What you see up there is an isotope symbol. They make it easier to use them (elements) in chemical equations. Note: All the Isotopes must be written in capital form. For example, the hydrogen in H 2 O Must be capitalized !!!! !!!!! !!!!
  14. 14. ELEMENTS Isotope Symbols H 2 O The capitalized letter is used to abbreviate the original element. The number however, the number is used to express the quantities of the element. In this case, is we were to read this element, it would say 2 hydrogen, and 1 oxygen, which is water. Reading the symbols
  15. 15. Thank You For Watching Our Presentation