1. Basic Chemistry CHAPTER 2

2. What are elements?  What can you tell me about elements?

3. What are elements?  Elements: The fundamental units of matter

4. What are elements?  Elements: The fundamental units of matter  What do we mean by fundamental?

5. Elements of the Body  96% of the body is made from 4 different elements

6. What are atoms?

7.  Atoms: The building blocks of elements

8. Atomic Structure  What are the different parts of an atom?

9. Atomic Structure  Nucleus  Protons (p + )  Neutrons (n 0 )  Outside of nucleus  Electrons (e - )

10. Atomic Structure of Smallest Atoms

11. How do we identify elements?

12.  Atomic number

13. How do we identify elements?  Atomic mass number

14. How do we identify elements?  Atomic mass number:

16.  Why are atomic masses not in whole numbers?  Protons + Neutrons right?

17. Isotopes and Atomic Mass  ISOTOPES!

18. Isotopes and Atomic Mass  Isotopes:  Have the same number of protons  Vary in number of neutrons

19. Isotopes and Atomic Mass  Close to mass number of most abundant isotope  Atomic weight reflects natural isotope variation

20. Electrons and Bonding  Energy levels called electron shells  Electrons closest to the nucleus are most strongly attracted

21. Electrons and Bonding  Bonding - interactions between electrons in the outer shell (valence shell)  Full valence shells do not form bonds

22. Electrons and Bonding  How to fill the atom’s shells  Shell 1 - maximum of 2 electrons  Shell 2 - maximum of 8 electrons  Shell 3 - maximum of 18 electrons  Shell 4 - maximum of 32 electrons  Shell 5 - maximum of 50 electrons  Shell 6 – maximum of 72 electrons

23. Lewis Dot Structures  Diagrams that show the bonding between atoms  Represent the valence shell  Carbon has 6 protons, 6 elections  So…….4 electrons are in the valence shell

24. Rule of Eights (Octet Rule)  Atoms are considered stable when their outermost orbital has 8 electrons  The exception to this rule of eights is Shell 1, which can only hold 2 electrons

25. Radioactivity  Radioactivity—process of spontaneous atomic decay  What can we use this for?

26. Radioactivity  Radioactivity—process of spontaneous atomic decay  What can we use this for?

27. Radioactivity  Radiometric Dating:  Uranium  238 U to 206 Pb, with a half-life of 4.47 billion years  235 U to 207 Pb, with a half-life of 704 million years.  Carbon  Carbon-14 is a radioactive isotope of carbon, with a half-life of 5,730 years  Very short compared to other isotopes

28. Molecules and Compounds  Molecule: Two or more like atoms combined chemically  Compound: Two or more different atoms combined chemically

29. What are chemical reactions?  What do you remember?

30. What are chemical reactions?  Atoms are united by chemical bonds OR  Atoms dissociate from other atoms when chemical bonds are broken