1. Warm-up For each of the following atoms: draw the Bohr model, list the # of e - and the # of valence e -. 1. Cl 2. P 3. Be 4. Si

2. Periodic Patterns  As a lab group, draw your assigned atoms. Then identify the pattern on the period table.  Share the pattern with the class  Record pattern on your periodic table

3. Ions

4. Ion Formation  Elements are nonreactive if they have full valence electrons shells (like the noble gases).  They GAIN or LOSE electrons in order to achieve 8 (or 2) valence electrons.  They will try to gain or lose the least number of electrons as they can (not more than 3)

5. Examples For the following atoms:  1. draw the Bohr model.  2. state how many electrons it is going to gain or lose to get a full valence shell –F –S –Li –Mg –Ar –H –He

6. Neutral Atoms  Have the same number of electrons as protons + + + + + + + + + + - - - - - - - - - -

7. Ion Definition: A atom (or molecule) that has a charge (like + or 2-, etc)  Cations are Positive  Examples Na + Fe 3+ Al 3+ Mg 2+  Anions are negative  Examples: O 2- F - P 3- S 2-

8. Homework:  Read: 4.10  Answer: 65-73 odd

9. Chemical Bonding Ionic Bonding

10. Definitions   Chemical bond: a force that holds 2 or more atoms together making them work as a unit.   Ionic bonding: when an atom reacts with another atom, it donates or receives electrons from it (becoming IONS). They are bonded together by electrical charge (+ and -). Metal bonded with non-metal.   Covalent bonding: when atoms share electrons to complete their valence electrons. The need for a complete valence energy level covalently bonds the atoms together. Non-metal bonded with non- metal.

11. Review   An Atom’s electron configuration is sometimes very reactive. What determines an atom’s reactivity is how full its outer energy level is.   If it is full, it is mostly unreactive: Ex: Noble gases.   If it is not, it can react with other atoms.   A full valence shell has 8 electrons in it. (with the exception of the first shell (2 electrons)

12. Lewis Dot Structures  A simpler version of the Bohr model that focuses on the valence e -  Write the symbol and draw dots for each valence e - around it. ArF CaNa AlN

13. Ionic Bonding   An atom that has less than 8 valence electrons will react to achieve a full valence shell.   It can either accept electrons or give them away   In most cases, an atom will not give or take more 3

14. Practice Na and Cl Ca and S K and O

15. Charges   If an atom gives away electrons it becomes + (cation)   If it takes electrons it becomes – (anion)   The attraction between the – and + charges forms an ionic bond.

16. Homework:  Ionic Homework Practice Sheet

17. Covalent Bonding   Covalent bonding: when atoms share electrons to complete their valence electrons. The need for a complete valence energy level covalently bonds the atoms together. Non-metal bonded with non-metal.

18. Covalent Bonding   Atoms will share to complete the valence shell. (8 or 2 for H/He)   Covalent Bonds share electrons (not give or take them)

19. Practice Cl + Cl F + F

20. Practice H + H H + H + O

21. Homework  Ionic + Covalent Practice Sheet

22. Ionic Bonding Chemical Formulas: Ions combine to form NEUTRAL MOLECULES  A molecule is a group of atoms bonded together chemically.  In order for molecules to be NEUTRAL, the charges MUST CANCEL OUT.  One negative charge cancels out one positive charge

23. Neutral Molecules  Neutral molecules have a ZERO NET CHARGE. Na + + F - = NaF Mg +2 + F - = MgF 2

24. To determine the chemical formula formed from two ions (ionic bonding) 1. Find the charge that each ion tends to get 2. Find the number of each cation and anion needed to cancel out the charge (lowest common denominator) 3. Combine the atoms such that there is an overall Zero charge

25. Ion Practice  For each atom write the ion it becomes. NaO MgN ClAl KrI

26. A mnemonic  SWAP AND DROP! Mg +2 F -1 MgF 2

27. Na and O Na 2 O

28. Mg and S MgS

29. Al and O Al 2 O 3

30. B and Cl BCl 3

31. Try The following yourself  Na and S  Al and I  Be and O  K and P  Ca and O  Al and N

32. Isotopes  Isotopes of Magnesium 1.Protons: 12, Neutrons: 12, Mass: 24 2.Protons: 12, Neutrons: 12, Mass: 24 3.Protons: 12, Neutrons: 12, Mass: 24 4.Protons: 12, Neutrons: 12, Mass: 24 5.Protons: 12, Neutrons: 12, Mass: 24 6.Protons: 12, Neutrons: 12, Mass: 24 7.Protons: 12, Neutrons: 12, Mass: 24 8.Protons: 12, Neutrons: 12, Mass: 24 9.Protons: 12, Neutrons: 13, Mass: 25 10.Protons: 12, Neutrons: 14, Mass: 26

33. Step for calculating the atomic mass Requirements: list of Isotopes and % of each isotope. 1. Convert each percent to a decimal (by dividing by 100 and removing %) 2. Multiply each isotope by its “percent as a decimal” 3. Add all the isotope answers from #2

34. Atomic Mass Practice  Element Mr has the following percentages of different isotopes: 56 Mr =71.2% 54 Mr =20.3% 57 Mr =8.5% What is Mr’s atomic mass?

35. More Practice  Element Lh has the following percentages of different isotopes: 11 Lh =19% 12 Lh =21% 13 Lh =27% 14 Lh =33% What is Lh’s atomic mass?

36. Molecule Game!  You will receive a few pieces of paper with an element on it. Your first job is to determine what each element’s charge is. DO NOT WRITE THE CHARGE ON THE PAPER!  You will then use ONE of your elements to join with some other folks to make a Neutral Molecule.  Rules: –There can only be 2 different elements in your molecule (for example, can’t have B Na AND F) –Your Molecule MUST be neutral based on the number of each atom –You can only use one of the elements you are given…not both. –When time is called, Ms. Tetler will check to make sure you have a neutral molecule.