1. Atom Structure Chapter 3

2. I. Defintion Atoms are the fundamental unit of which elements are composed. Atoms are the fundamental unit of which elements are composed.

3. II. Structure What makes up an atom? What makes up an atom? –3 Subatomic particles

4. SubatomicParticleFoundCharge Mass (amu)

5. III. Atomic Mass Where is the mass of the atom found? Where is the mass of the atom found? –Nucleus p + n = amu p + n = amu

6. IV. Periodic table

8. V. Practice Li Li Ne Ne Cl Cl How many protons, neutrons, and electrons? How many protons, neutrons, and electrons?

9. VI. Atomic Notation

10. Lets try!

11. VII. Isotopes Why is the AMU not a whole number? Why is the AMU not a whole number? –ATOMIC MASS IS AN AVERAGE MASS OF ALL ATOMS OF AN ELEMENT ISOTOPE – Different numbers of neutrons in nucleus. ISOTOPE – Different numbers of neutrons in nucleus.

12. Isotopes Protons job- giving the element it’s identity Protons job- giving the element it’s identity Neutron’s job - give the element more mass Neutron’s job - give the element more mass Isotopes- same element (same # of protons), but different masses (so the # of neutrons can change!) Isotopes- same element (same # of protons), but different masses (so the # of neutrons can change!)

13. Isotopic Notation This would be Carbon-14 This would be Carbon-14 (the name of the element (dash) the mass of the element) (the name of the element (dash) the mass of the element) This is Carbon-12 This is Carbon-12

14. Example: Chlorine has a mass on the periodic table of 35.453 amu. Example: Chlorine has a mass on the periodic table of 35.453 amu. There are 2 isotopes of chlorine. There are 2 isotopes of chlorine. 75% chlorine-35 75% chlorine-35 25% chlorine-37. 25% chlorine-37. ISOTOPES CONT….

15. Sample Problem Chlorine-35 has an atomic mass of 34.969 amu and has an abundance of 75.770%. Chlorine-37 has an atomic mass of 36.966 amu and has an abundance of 24.230%. Calculate the average atomic mass of chlorine. Chlorine-35 has an atomic mass of 34.969 amu and has an abundance of 75.770%. Chlorine-37 has an atomic mass of 36.966 amu and has an abundance of 24.230%. Calculate the average atomic mass of chlorine. Step 1: Multiply the mass of each isotope by its percent abundance Step 2: Sum the results

16. You Try Calculate the average atomic mass for element X. Can you figure out what X is? It is Used to treat mental disorders. Calculate the average atomic mass for element X. Can you figure out what X is? It is Used to treat mental disorders. ISOTOPE MASS (AMU) Abundance% 6X6X6X6X6.0157.5% 7X7X7X7X7.01692.5%

17. VIII. IONS A neutral atoms have same # of protons and electrons. A neutral atoms have same # of protons and electrons. Atoms can gain or lose electron(s) becoming a charged ion Atoms can gain or lose electron(s) becoming a charged ion Example: Na has 11 protons and 11 electrons Example: Na has 11 protons and 11 electrons

18. IONS Na can lose 1 electron making it have a charge of +1 Na 1+ or Na +

19. IONS Some elements can become negative ions by GAINING electrons. Some elements can become negative ions by GAINING electrons.

20. IONS Will gain 1 electron therefore an overall (1-) charge. 9 + + 10 - = 1 - F - F -

21. Ions Charges & The Periodic Table Label these on your periodic tables Atoms want to be like the noble gases (group 8) because noble gases are very stable (unreactive/inert)… Other atoms will lose/gain electrons to become like one.

22. IX. Bohr Diagrams Sec 11-2 (p. 366)

23. Wave Mechanical Model

24. A. Electron Energy Levels Energy levels begin closest to nucleus & move further out 1 st energy level = max. of 2 e- 2 nd energy level = max. of 8 e- 3 rd energy level = max. of 8 e-

25. An energy level must be full before electrons move to the next level. An element is more stable when energy levels are full

26. Practice- Lets draw them! 1.Lithium 1.Magnesium