1 / 7

Periodic Properties: Groups I and II Group I—The Alkali Metals

Periodic Properties: Groups I and II Group I—The Alkali Metals Elements and Symbols Ion. Energy(kJ/mol) 2 nd Ion. En. Li = Lithium 520 7300 Na = Sodium 495 4560 K = Potassium 419 3052 Rb = Rubidium 403 2633 Cs = Cesium 376 2230 Reactivity with water

zoltan
Download Presentation

Periodic Properties: Groups I and II Group I—The Alkali Metals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Periodic Properties: Groups I and II • Group I—The Alkali Metals • Elements and Symbols Ion. Energy(kJ/mol) 2nd Ion. En. • Li = Lithium 520 7300 • Na = Sodium 495 4560 • K = Potassium 419 3052 • Rb = Rubidium 403 2633 • Cs = Cesium 376 2230 • Reactivity with water • These elements need to lose 1 e- to be like a Noble Gas • Losing electrons is called “oxidation” • Water can gain electrons (“reduction”) • 2 M0(s) + 2 H2O(l) ------> 2 MOH(aq) + H2(g) • Example: 2 Na0(s) + 2 H2O(l) ------> 2 NaOH(aq) + H2(g) • Reactions are violently exothermic • Basic solutions are formed

  2. Sodium metal reacting with water

  3. Reactions with Oxygen • 4Li + O2 2Li2O Lithium Oxide [O2- is called oxide;] • 2Na + O2 Na2O2 Sodium Peroxide [O22- is called peroxide] • K + O2 KO2Potassium Superoxide [O2- is called superoxide] • Rb + O2 RbO2Rubidium Superoxide • Cs + O2 CsO2Cesium Superoxide B. Group II—The Alkaline Earth Metals • Elements and Symbols Ion. Energy(kJ/mol) 2nd Ion. En. • Be = Beryllium 900 1757 • Mg = Magnesium 738 1450 • Ca = Calcium 590 1145 • Sr = Strontium 550 1064 • Ba = Barium 503 965 • Reactions with Oxygen • Much more predictable: 2 M0(s) + O2(g) ------> 2 MO(s) • 2 Ca0(s) + O2(g) ------> 2 CaO(s)

  4. 3. Reactivity with water • These elements need to lose 2 e- to be like a Noble Gas • M0(s) + 2 H2O(l) ------> M(OH)2(aq) + H2(g) • Example: Mg0(s) + 2 H2O(l) ------> Mg(OH)2(aq) + H2(g) • Reactions are slow, with some bubbling visible • Basic solutions are formed 4. Reactivity with Acid a. M0(s) + 2 HCl(aq) ------> 2 MCl2(aq) + H2(g) • Mg0(s) + 2 HCl(aq) ------> 2 MgCl2(aq) + H2(g) • Ionization Energy • The energy required to remove an e- from a gaseous element • X(g) + I.E. ------> X+(g) + e- • More reactive metals have lower Ionization Energies • Ionization Energy decreases down a Group—the electron being removed is farther from the nucleus, thus easier to remove • Ca (I.E. = 590 kJ/mol) is more reactive than Mg (I.E. = 738 kJ/mol) • K (I.E. = 419 kJ/mol) is more reactive than Li (I.E. = 520 kJ/mol)

  5. Calcium Metal Reacting with Water to Form Bubbles of Hydrogen Gas

  6. Metal Oxides and Water • The Alkali and Alkaline Earth Metals react with water to make it basic • 2 Na0(s) + 2 H2O(l) ------> 2 NaOH(aq) + H2(g) • Mg0(s) + 2 H2O(l) ------> Mg(OH)2(aq) + H2(g) • The oxides of these metals also react with water to make basic solutions • 2KO2(s) + 2H2O(l) ------> 2KOH(aq) + O2(g) + H2O2(aq) • MgO(s) + H2O(l) ------> Mg(OH)2(aq) E. Notes on Today’s Lab • Do the reactions in the hood: H2 is produced • Do Part A first (metal hardness); then use same piece for Part B (H2O rxn) DON’T THROW METALS IN TRASH: THEY CAN CATCH ON FIRE 2 M0(s) + 2 ROH(l) ------> 2 M+OR-(aq) + H2(g) • Use the Bunsen burner in the hood to burn the Magnesium • Phenolpthalein is red under basic conditions • Orange pH paper turns blue under basic conditions

  7. Incident: Sodium Metal-Solvent Fire

More Related