1. Variation in Atomic Structure: Isotopes and Ions Monday November 14 th and Tuesday November 15 th

2. Question: The mass of an atom of an element can change without changing the element… What subatomic particles must change in order for this to occur? Neutrons; changing the protons would change the element!!!

3. proton neutron electron BERYLLIUM ISOTOPES BERYLLIUM ISOTOPES Isotopes Element with same amount of protons but different amounts of neutrons.

5. EXAMPLE OF AN ISOTOPE Cl 35 17 Cl 37 17 20 NEUTRONS ATOMIC MASS 18 NEUTRONS ATOMIC NUMBER

6. Average Atomic Mass Average mass of all isotopes of an element Relative to the other elements around. Determined by taking the sum of mass of all the isotopes multiplied by their relative abundances

7. Calculating Atomic mass Example: Rubidium has two common isotopes, 85Rb and 87Rb. If the abundance of 85Rb is 72.2% and the abundance of 87Rb is 27.8%, what is the average atomic mass of rubidium? ∑ (85 amu X.722) + (87 amu X.278) –61.37amu + 24.186 amu) Answer: 85.56 amu

8. Practice: Magnesium has three isotopes Magnesium-2478.70 % abundant Magnesium-2510.13% abundant Magnesium-2611.17% abundant Determine average atomic mass of magnesium. Units are amus

9. How are ions produced?  Elements gain or lose electrons  Valence electrons- outer energy level electrons  Octet Rule- All elements want to be like the noble gases (group 18), so they gain or lose electrons in order to become stable.  Column= # of valence electrons from 1-8  Exception- Helium- has 2 valence electrons  Determined from electron dot diagrams

10. Electron Dot Diagrams Steps to follow: 1) Write the symbol of the element listed. 2)Surround the symbol with valence electrons.

11. Electron Dot Diagrams of first 20 elements

12. What are ions?  Atoms of an element that differ in electrons  Two types:  Cations- lose electrons; become positively charged  Column 1= loses 1  Column 2= loses 2  Column 3= loses 3  Anions- gain electrons; become negatively charged  Column 15= gains 3  Column 16= gains 2  Column 17= gains 1  Column 18= stable

13. Writing Ions Write the elements symbol Using a superscript, write a positive or negative charge. –Positive- loses electrons –Negative- gains electrons Write the number lost or gained next to the charge.

15. SOME ATOMS GAIN ELECTRONS SOME ATOMS GAIN ELECTRONS O - - - - - - - - - - - - - - - - O -2 - - - - - - - - - - - - - - - - - - - - ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS

16. Making Ions: Practice Draw the electron dot diagrams and the ions formed by the following elements: –Hydrogen –Lithium –Magnesium –Oxygen –Aluminum –Phosphorus (Hint: Ions should include the element’s symbol and a superscript charge showing the amount of electrons gained or lost)

17. The Location of Electrons Wednesday November 15 th and Thursday November 16 th

18. Energy Levels Energy levels- determine the amount of energy an electron has. Energy levels= n = quantum number n= 1= 1 st energy level n= 2 = 2 nd energy level n=3= 3 rd energy level All the way up to the 7 th energy level

19. Sublevels Organized on the periodic table into S,P,D, F Energy level= # of sublevels

20. S Sublevel

21. P Sublevel

22. Orbitals probable location to find an electron n 2 = # of orbitals for each energy level S: 1 orbitalP: 3 orbitals D: 5 oribtalsF: 7 orbitals Three rules to follow when electrons fill orbitals. –Aufbau Principle Each electron occupies lowest energy orbital first –Pauli Exclusion Principle two electrons can occupy 1 orbital –Hund’s Rule Electrons occupy each orbital with one electron before filling the orbital with two

23. To Review: Electrons fill to become stable. No more than 2 electrons per orbital 2n 2 = # of electrons per energy level

24. Electron Configurations  Displays the following:  # of each energy level  letter of each sublevel  # of each electron in that sublevel as a subscript

25. Electron Configurations Examples: Hydrogen 1s 1 Helium –1s 2 Lithium –1s 2 2s 1 Beryllium –1s 2 2s 2

26. More Examples Boron –1s 2 2s 2 2p 1 Carbon –1s 2 2s 2 2p 2 Nitrogen –1s 2 2s 2 2p 3 Oxygen –1s 2 2s 2 2p 4 Fluorine –1s 2 2s 2 2p 5 Neon –1s 2 2s 2 2p 6

27. In-class Practice Draw electron configurations for the rest of the first 20 elements on the periodic table.

28. Bohr Models Friday November 18 th and Monday November 28 th

29. Making Bohr Models. 1)Determine the # of protons, neutrons and electrons in the element. 2)Draw a circle to represent nucleus. Inside of circle, write # of protons and neutrons. 3)Draw circles around the nucleus based on how many levels the element has. 4)Insert electrons according to the rules learned about electron location. 1 st energy level= 2 electrons 2 nd energy level= 8 electrons 3 rd energy level= 8 electrons (can be up to 18) 4 th energy level= 8 electrons (can be up to 32)

30. Bohr Model Practice Hydrogen- Helium- Lithium-

31. Draw Bohr Models for the rest of the 1 st 20 elements.

32. Homework Chapter Review Pennium Lab