Intro to Chemistry

1. Intro to Chemistry Chemistry PowerPoint # 1

2. Blind Men and the Elephant • Click here to read

4. Element • Element – a substance that cannot be broken down into another substance by chemical or physical means.

5. Atom • Atom – the basic unit of matter, the smallest particle of an element. • Nucleus • Electron cloud

6. Element Song • Make sure speakers are hooked up and volume is up! • Click here to watch

7. Dmitri Mendeleev • 1869, Russian scientist • Recognized hidden patterns in the elements • Similar chemical and physical properties http://arjunpuri.files.wordpress.com/2009/10/6-dmitri-mendeleev.jpg

8. Dmitri Mendeleev • Recorded two important facts • Atomic Mass • Bonding Power Mendeleev arranged first periodic table by atomic mass. http://0.tqn.com/d/chemistry/1/0/0/W/mendeleevperiodic.jpg

9. Periodic – a regular repeated pattern

10. Periodic Table • Periodic Table – chart of elements showing repeating pattern of their properties http://lgimages.s3.amazonaws.com/data/imagemanager/4404/periodic_table_access_science.gif

11. In the nucleus of an atom • Nucleus – core of the atom • Proton – positively charged particles in the nucleus • Neutron – uncharged particle in the nucleus http://www.phscale.net/atom-model.gif http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/Graphics/atom.jpg http://www.sciencewithmrmilstid.com/media/atom.jpg

12. Outside the nucleus of an atom • Electrons – negatively charged particles outside the nucleus. • Move constantly and rapidly around nucleus • 2000 times less the mass of a proton Activity http://www2.renesas.com/faq/en/images/ele2.gif http://www.greenenergybuild.com/images/illust_silicon_electrons.gif

13. Weight? • Parts of an atom are so small they created their own unit of measurement… AMU or Atomic Mass Unit 1 AMU = weight of 1 proton

14. Mass vs. Weight • Mass = the amount of space an object occupies • Weight = based on the amount of gravitational pull on an object Ex. An astronaut on the moon has the same mass as on earth, but their weight is different.

15. Atomic Mass • Atomic Mass – the average mass of one atom of the element. • Most of the mass of an atom is in the nucleus. • Difference due to different # of neutrons in the nucleus. Activity http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif

16. Atomic Number • Atomic Number – number of protons in the nucleus. • Unique property that indentifies an element • Constant for all atoms of an element • Periodic table is now organized by atomic number http://www.green-planet-solar-energy.com/images/helium-atom.gif http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif

17. Reading the periodic table http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif

18. Element Symbol • Element Symbol – 1 or 2 letters representing the element. • First letter capitalized, second letter lowercase O He Fe Si C N P Al Cl

19. Organization of the Periodic Table • Today – arranged by atomic number • Element property determined by location on PT

20. Group/Family • Group – elements in the same vertical column of the periodic table. 18 total groups

21. Specific Groups • Elements in each group have similar characteristics. Group 1 – react violently with water Group 11 – elements react slowly with water Group 18 - rarely react at all

22. Period • Period – each horizontal row across the periodic table. • Properties are not alike • Gradually change properties as you move Left to Right. More reactive on left, Inactive gas on right. 7 total periods

23. Calculating Protons and Electrons • Atoms have a neutral overall charge, meaning # of protons = # of electrons • Element = Atomic Number = # of protons = # of electrons Fe = 26 (atomic number) = 26 protons = 26 electrons Pb = 82 (atomic number) = 82 protons =82 electrons

24. Give it a try Element = atomic number = protons = electrons Au = __________ = 79 = _____ Ta = 73 = _______ = ________ ______ = ________ = _________ = 53 ______ = 70 = _______ = _________ Pa = _______ = ________ = ________

25. Calculating neutrons (Rounded Atomic Mass) – (atomic #) = # neutrons • Round the atomic mass to the nearest whole # • Subtract the atomic number from the atomic mass • This number equals the number of neutrons Ex. Mercury (Hg) Atomic Mass = 200.59 Atomic Number = 80 201 – 80 = 121 neutrons

26. Give it a try (Rounded Atomic Mass) – (atomic #) = # neutrons Be ________ - 4 = 5 neutrons V 51 – 23 = ______ neutrons Rh 103 - ______ = 58 neutrons Ar _______ - 18 = _______ neutrons Ga _______ - ______ = _______ neutrons

27. Valence Electrons Valence Electrons – electrons available to be lost, gained, or shared in the formation of chemical compounds. Furthest from the nucleus. Electrons are in layers, only the outer layer can be shared or transferred (valence electrons) http://hyperphysics.phy-astr.gsu.edu/hbase/solids/imgsol/valen.gif

28. Valence Electrons