chap 9 full - 1 CHEM 1A03 Intro Chemistry I Essential...

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Unformatted text preview: 1 CHEM 1A03: Intro. Chemistry I Essential Elements: Chemistry, Life & Health Ch.9: The Periodic Table and Some Atomic Properties Department of Department of 1 Chemistry Chemistry Atomic Properties Natural Abundance of Elements on Earth Department of Department of 2 Chemistry Chemistry Precious metals ($) Silicates (Feldspar/Quartz): Most abundant mineral in crust Top 7 Elements: O > Si > Al > Fe > Ca > Na ≈ K Noble gases, Group 18 (8A) • n s 2 n p 6 stable electron configurations • Other elements try to attain these configurations • Considered chemically “inert” until 1962 – many noble gas compounds known, including e g KrF 2 XeF 2 XeF 4 XeF 6 Department of Department of 3 Chemistry Chemistry e.g. KrF 2 , XeF 2 , XeF 4 , XeF 6 XeO 3 , XeOF 2 # , XeOF 4 , XeO 2 F 4 Much of this research based at McMaster ! # Brock, D. S., et al. , J. Am. Chem. Soc. , 129 , 2007, 3598-3611. p. 344 Non-metals • Main group (s and p block) non-metals tend to gain electrons Department of Department of 4 Chemistry Chemistry p. 345 Example: Descriptive Halogens Chemistry 1) Ability to oxidize increases up the group (towards F). For example: YES: Cl 2 (g) + 2 I − (aq) → I 2 (aq) + 2 Cl − (aq) NO: Br 2 (l) + Cl − (aq) → no rxn Department of Department of 5 Chemistry Chemistry 2)They react with metals to form salts! e.g. NaCl 2 Na(s) + Cl 2 (g) → 2 NaCl(s) Fig. 9-15 Fig. 9-16 p. 362 Example: Descriptive Halogens Chemistry 3) Halogen mp/bp increases down group 17A (more on this in Ch 12) Department of Department of 6 Chemistry Chemistry Fig. 9-12 Cl 2 (g), Br 2 (l), I 2 (s) p. 360 2 Metals • Main group (s and p block) metals (and H) tend to lose electrons Department of Department of 7 Chemistry Chemistry p. 344 Example: Group 1 and 2 metals • Alkali metals (Group 1) oxidize more readily than alkaline earth metals (Group 2) [Fig. 9-14]; both oxidize easily in water. Department of Department of 8 Chemistry Chemistry K Ca, with phenolphthalein Make sure you can write these reactions! p. 361 General trends in physical properties – Metallic properties decrease across a group – Across a period, melting point (mp) varies with type of solid ( type of bonding ): Department of Department of 9 Chemistry Chemistry (Ch 12): Metals (Na, Mg) Metalloid (Si, network solid) Non-metals (P, S, Cl, molecules, and Ar, atoms) Fig. 9-13 p. 360-361 A key idea for periodic trends: Screening • Outer e − of an atom are screened by the core e − from feeling the full attractive charge (Z) from the nucleus • Outer e − feel an effective nuclear charge, Z effective Department of Department of 10 10 Chemistry Chemistry • Simply, , where S = # core e − • In reality, s, p and d e − are screened to different extents; outer e − also screen each other [note: omit eq. 9.5] S Z Z eff − = p. 348 Atomic radius (Fig. 9-4) Department of Department of 11 11 Chemistry Chemistry p. 347-350 Atomic radius – general trends • Decreases across a period – Z increases, and e...
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This note was uploaded on 04/03/2010 for the course CHEMISTRY Chem 1A03 taught by Professor Lock during the Spring '02 term at McMaster University.

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chap 9 full - 1 CHEM 1A03 Intro Chemistry I Essential...

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