2. C HEMISTRY – 11 TH G RADE

3. O BJECTIVES Students will learn: Composition of an atom Charges of subatomic particles Location of subatomic particles How to determine the number of each subatomic particle in an atom using the periodic table

4. W HAT A RE A TOMS M ADE O F ? Atoms are composed of 3 types of subatomic particles: Positively charged PROTONS Negatively charged ELECTRONS Neutral NEUTRONS (no charge)

5. W HERE A RE T HESE S UBATOMIC P ARTICLES F OUND I N THE A TOM ? Protons and neutrons are located in the nucleus ; they never go outside of the nucleus Electrons are found outside of the nucleus in the electron cloud

6. C OMMON M ODEL O F A N A TOM

7. U SING T HE P ERIODIC T ABLE C 6 12.0107 Atomic Number Atomic Symbol Atomic Mass

8. D ETERMINING THE N UMBER OF P ROTONS The number of protons = the atomic number C 6 12.0107 Carbon is atomic number 6 Carbon has 6 protons

9. D ETERMINING T HE N UMBER O F E LECTRONS The number of electrons = the atomic number C 6 12.0107 Carbon is atomic number 6 Carbon has 6 electrons

10. I MPORTANT N OTE Only in a neutral atom are the number of protons and the number of electrons equal. This is because the negative charge of the electron will cancel out the positive charge of the proton. This is just like a math problem where 1 + (-1) = 0

11. D ETERMINING THE N UMBER OF N EUTRONS The number of neutrons = atomic mass – atomic number C 6 12.0107 Carbon is atomic number 6 Carbon has an atomic mass of 12 amu 12 – 6 = 6 neutrons

12. N UMBER OF S UBATOMIC P ARTICLES I N C ARBON 6 protons 6 electrons 6 neutrons

14. Imagine you are a scientist working in the field and an atom of an unknown element has been discovered. You later find that the atom has 78 protons. What is the element? Gold Silver Platinum Mercury

15. Next Question

16. Try Again

17. If a neutral atom was found and it contained 24 electrons, how many neutrons would there be? 26 25 28 30

18. Next Question

19. Try Again

20. What is the name of the element (containing 24 electrons and 28 neutrons) discovered in the previous question? Chromium Manganese Cobalt Iron

21. Next Question

22. Try Again

23. True or False: The number of electrons in an atom is always equal to the number of protons. True False

24. References

25. Try Again

26. R EFERENCES Books: Smith, J. G. (2010). General, organic, and biological chemistry. (2nd ed.). New York, NY: McGraw-Hill. Images: Image: “Thinker”“Thinker” http://office.microsoft.com/en- us/images/results.aspx?qu=thinker&ex=2&AxInstalled=copy&Do wnload=MM900043731&ext=GIF&c=0#ai:MM900043731| Found on: office.microsoft.com Image: “Stylized Atom 2”“Stylized Atom 2” http://openclipart.org/detail/47179/stylized-atom-2-by-j_alves Found on: openclipart.org