1. Basic Chemistry CHAPTER 2-2

2. Radioisotopes  Heavier isotopes that are unstable and tend to decompose to become more stable

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

4. Radioactivity  But how does this happen?

5. Radioactivity  But how does this happen?  nuclei are unstable so dissipate excess energy by emitting radiation in alpha, beta, or gamma rays

6. 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

7. Radioactivity  PhET Simulation  https://phet.colorado.edu/en/simulation/beta-decay

8. Inert Elements  Atoms are stable (inert) when the outermost shell is complete

9. Inert Elements  Atoms are stable (inert) when the outermost shell is complete  Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state

10. Inert Elements  Atoms are stable (inert) when the outermost shell is complete  Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state  Atoms are considered stable when their outermost orbital has 8 electrons (With exception to the first shell

11. Inert Elements

12. Reactive Elements  Valence shells are not full and are unstable  Tend to gain, lose, or share electrons  Allow for bond formation, which produces stable valence

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

14. Molecules and Compounds https://phet.colorado.edu/en/simulation/build-a-molecule

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

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

17. Chemical Bonds  Ionic vs. Covalent  https://www.youtube.com/watch?v=fH GSSV466Gk

18. Ionic Bonds  Form when electrons are completely transferred from one atom to another  Ions  Charged particles  Anions - negative  Cations - positive  Either donate or accept electrons

19. Ionic Bonds +– Sodium atom (Na) (11p + ; 12n 0 ; 11e – ) Chlorine atom (Cl) (17p + ; 18n 0 ; 17e – ) Sodium ion (Na + )Chloride ion (Cl – ) Sodium chloride (NaCl) ClNaCl Na

20. Covalent Bonds  Atoms become stable through shared electrons  Single covalent bonds share one pair of electrons  Double covalent bonds share two pairs of electrons

21. Covalent Bonds - Example

24. Covalent vs. Ionic bonds https://phet.colorado.edu/en/simulation/sugar-and-salt-solutions

25. Covalent vs. Ionic bonds https://www.youtube.com/watch?v=mHKGLawOTww https://www.youtube.com/watch?v=9WXTbkBGPrE https://www.youtube.com/watch?v=dD0Xl4acUFg

26. Polarity  Covalently bonded molecules

27. Polarity  Some are non-polar  Electrically neutral as a molecule  Some are polar  Have a positive and negative side

28. Polarity  https://phet.colorado.edu/en/simulation/mol ecule-polarity

29. Hydrogen bonds  Weak chemical bonds  Hydrogen is attracted to the negative portion of polar molecule  Provides attraction between molecules

30. Hydrogen bonds

31.  How many drops of water can you fit on a penny?  Who can guess correctly??