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Chemical Symbols in the Periodic Table

Chemical Symbols in the Periodic Table. How is the Periodic Table Arranged?. Alphabetically from A to Z By atomic mass, from small to large By number of protons, starting with 1 Randomly In the order the elements were discovered. Periodic table is arranged by number of protons !.

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Chemical Symbols in the Periodic Table

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  1. Chemical Symbols in the Periodic Table

  2. How is the Periodic Table Arranged? • Alphabetically from A to Z • By atomic mass, from small to large • By number of protons, starting with 1 • Randomly • In the order the elements were discovered

  3. Periodic table is arranged by number of protons! This is also by Atomic Number By coincidence, the elements are generally in order of increasing atomic mass, but not always…..

  4. Cobalt has 27 protons, mass = 58.9 amu Next after Co comes Nickel Nickel has 28 protons , but mass = 58.7 amu (less mass than cobalt) For example….

  5. Periods Periods are the horizontal rows. There are 7 periods 1 2 3 4 5 6 7 (6) (7)

  6. Groups or Families Groups (also called families) are the vertical columns. There are 18 groups. 1 18

  7. Most elements are metals

  8. Non-metals live in upper right corner (except Hydrogen)

  9. 6 Metalloids live near the red stair:B, Si, Ge, As, Sb, Te X

  10. Group 1 metals are called alkali metals

  11. Group 2 metals are called alkaline earth metals

  12. Transition Metals are in groups 3 through 12They tend to form colorful ions and compounds

  13. Halogens are in group 17 Noble gases in group 18

  14. 7 elements are DIATOMIC

  15. Allotropes Elements that can exist in different forms in the same phase are allotropes: O2 (oxygen gas) and O3 (ozone) are allotropes Allotropes have different chemical and physical properties

  16. Valence Electrons Definition: all the electrons in an atom’s HIGHEST ENERGY LEVEL

  17. Valence Electrons Remember: There are seven energy levels Energy Level 1 can hold two e- in S orbital Energy Level 2 can hold two e- in S, 6 in P Energy Level 3 : S, P, D Energy Level 4-7: S, P, D, F

  18. However…. Since according to the aufbau principle d and f orbitals fill after the S and P orbitals in the next highest energy level, Valence electrons are always in S or P orbitals (2 in S) + (6 in P) = 8 (max) Valence e-

  19. How to determine which e- are valence e- : Step 1: Write out the electron configuration for the atom 11Na = 1S22S22P63S1 Step 2: Count how many e- in the highest energy level: Energy level 3 = highest, so there is 1 valence e- Level 3 is highest

  20. The good news: It is easy to determine valence e- simply by looking at the periodic table: Group 1 has 1 valence e- Group 2 has 2 Group 13 has 3 Group 14 has 4 Group 15 has 5…….. Group 18 has 8

  21. What about the transition metals? For now, assume that they have 2. But sometimes they can also have 1, or 3 or more

  22. Write out the e- configuration for the following elements, then check and see what Group they are in: 12Mg 8O 17Cl 18Kr 26Fe 19K

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