1. UNIT 17 Review, Part II Atoms, Electrons, Periodic Table & Nuclear

2. Mass # Atomic # Nuclear symbol: Isotope name: carbon-12 Element Symbol

3. ISOTOPES:  Same protons, different # neutrons  Atoms of the same element with different mass numbers. Mass # = p + n Atomic # = p

4. C. Johannesson B. Isotopes  Chlorine-37 atomic #: mass #: # of protons: # of electrons: # of neutrons: 17 37 17 20

5. C. Johannesson Change in electron # = ION zIon Formation yAtoms gain or lose electrons to become more stable. yIsoelectronic with the Noble Gases. (Full Octet)

6. Electromagnetic Spectrum: LPChem:Wz:1415 The Electromagnetic Spectrum (all the “colors” of light) ROYGBV High Energy Low Energy

7. Electromagnetic Radiation: Light zWavelength and frequency are inversely proportional yAs wavelength increases, frequency decreases (and vice versa. LPChem:Wz:1415 c =  c = the speed of light: 3.0 x 10 8 m/s The speed of light is a constant. 3.0 x 10 8 m/s will be the value of “c” whenever you solve this equation.

8. Electromagnetic Radiation: Light zA certain Utah radio station broadcasts at 99.5 FM zFM radio stations give their frequencies in megahertz  99.5 FM = 99.5 x 10 6 Hz = frequency (  yWhat is the wavelength used by this radio station? LPChem:Wz:1415 c =  3.0 x10 8 m/s =  99.5 x 10 6 Hz1/s 3.0 x10 8 m/s 99.5 x 10 6 1/s = = 3.02 m The radio waves that 99.5 FM broadcasts on are 3 meters long.

9. Electromagnetic Radiation: Light zFrequency and ENERGY are directly proportional yAs frequency increases, the energy of the light increases. LPChem:Wz:1415 E = h  h = Planck’s Constant: 6.626 x 10 -34 J  s This number will be the value of “h” whenever you solve this equation. E is energy (in Joules) is still frequency (in Hz or 1/s)

10. Electromagnetic Radiation: Light zWhat is the Energy of the light (radio) wave 99.5 FM broadcasts on? LPChem:Wz:1415 E = h  E = 6.626 x 10 -34 J  s  99.5 x 10 6 Hz 1/s E = 6.59 x 10 -26 J 99.5’s radio signal is carried by waves of light with an energy of 6.59 x 10 -26 J. Why so little energy? That is the energy generated by just ONE electron in ONE atom.

11. Energy in the Atom zElectrons are most stable at the lowest available energy (ground state) and will always return to ground as soon as possible. yAny level above ground state is considered an “excited state” yThe electron is “excited” when above ground state. LPChem:Wz:1415

12. Each element gives off (and absorbs) a unique set of wavelengths. These spectra are used as “fingerprints” to identify elements. LPChem:Wz:1415

13. C. Johannesson A. General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”

14. B. Blocks s p d f

15. C. Periodic Patterns zAufbau Series: the order in which electrons fill energy levels & sublevels. 3p 6 4s 2 1s 2 2p 6 3s 2 4p 6 3d 10 2s 2 … 5p 6 6d 10 4d 10... 4f 14 6s 2 5d 10 5s 2 7p 6 6p 6 7s 2 5f 14

16. 1s 2 Sulfur’s last 4 electrons are in 3p. C. Electron Configuration zGives the energy state for all the electrons in an atom. zSulfur’s configuration needs to include ALL 16 of its electrons. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 2s 2 2p 6 3s 2 3p 4 All e-configs start at 1s. Powers should add up to atomic # (2+2+6+2+4=16)

17. zShorthand (Noble Gas) Configuration S 16e - Valence Electrons Core Electrons (up to previous Noble) S16e - [Ne-10] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4 B. Notation zLonghand Configuration

18. B. Mendeleev vs. Moseley zMendeleev organized elements in the periodic table by increasing atomic mass. (There were some discrepancies.) zMoseley organized elements in the periodic table by increasing atomic number. (This resolved the discrepancies.) yThe Modern Periodic Law: xWhen elements are ordered by atomic number, chemical and physical properties recur periodically.

19. 1 2 3 4 5 6 7 8  # valence electrons increases, left to right: B. Reaction Patterns Valence #s go by column, which is why properties go by column.

20.  Elements within a GROUP have similar properties  Because they have similar electron arrangements. Periodic Table Sections 1s 1 2s 1 3s 1 4s 1 5s 1 6s 1 7s 1

21.  A group or “family” is a column on the periodic table, e.g., the alkali metals or the noble gases. B. Groups

22.  A period is a row on the periodic table– all the way across, regardless of block. B. Periods Period 6 includes 6s, 5d, 6p and 4f Period 4: 4s, 3d, 4p

23. Periodic Trends zUp and to the right increases: yIonization energy yElectronegativity yElectron Affinity zDown and to the left increases: yAtomic radius zReactivity is up/right for nonmetals zReactivity is down/left for metals

24. Periodic Trends zRule of thumb: yUp and to the right, electrons are held more tightly. yLower and to the left, electrons are held more loosely.

25. Ionic Radius  Cations (+) Created by losing e - smaller than parent atom  Anions (–) Created by gaining e - larger than parent atom G. Ionic Radius

26. A. Types of Radiation  Alpha particle (  )  helium nucleus paper 2+  Beta particle (  -)  electron 1- lead  Positron (  +)  positron 1+  Gamma (  )  high-energy photon 0 concrete

27. C. Johannesson B. Nuclear Decay  Alpha Emission parent nuclide daughter nuclide alpha particle Numbers must balance!!

28. C. Johannesson C. Half-life  Half-life (t ½ )  Time required for half the atoms of a radioactive nuclide to decay.  Shorter half-life = less stable.

29. C. Half-life Iodine-131 is used to treat thyroid cancer. The half-life of I-131 is 8 days. 24 days ago, a doctor obtained a 48 g sample of I-131. How many grams of I- 131 remain? 24 days / 8 days = 3 half-lives 1 st decay: 48g ÷ 2 = 24g 2 nd decay: 24g ÷ 2 = 12g 3 rd decay: 12g ÷ 2 = 6g

30. Which reaction type? Less Energy More Energy