Transition Group Elements

Chapter 22: All

• Reading Preparation
• WebLecture
• Study Activity
• Preparation work for chat
• Online Quiz
• Lab Instructions

Reading Preparation

Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 22: All

Study Notes

• 22.1 Properties of the transition elements: Most transition elements are solid (the only exception is mercury) and shiny, ductile, malleable, excellent heat and electrical conductors, and they react variously with oxidizing agents to form ionic compounds. They are important catalysts in biological reactions, important pigments in paints and dies, and they provide color in many gems and semiprecious stones. Transition elements all have d orbitals with 1 to 10 electrons, and 1 to 2 s orbital electrons at a higher energy level, which are removed during oxidation. Metal ions frequently have oxidation numbers of two or three, matching their ionic charge. Radii, density, and melting point increase across the road to the midpoint, then drop.
• 22.2 Metallurgy is the technology for extracting metals from ores and creating alloys. Copper, silver, and gold occur in nature as free elements; most others occur as oxides, sulfides, halides, or carbonates. Pyrometallurgy (high temperature reactions) and hydrometallurgy (aqueous solutions) are both used to extract care metals from their ores. The ores may then be recombined with other elements to adjust flexibility, hardness, strength, and malleability. In particular, iron is combined with carbon to form steel.
• 22.3 Coordination compounds are structural units containing coordination complexes. These molecular units are solid ionic compounds containing both cations and anions arranged in a regular array (all hydrates fall into this category). A central metal ion forms ionic bonds to other molecules or ions (ligands), resulting in a neutral or ionic complex. Ligands which attached to the central ionized metal atom with more than one bond are polydentate or chelating ligands. Chelating ligands such as hemoglobin and chlorophyll play important roles in biochemistry. Because of their importance, coordination compounds have specific naming conventions.
• 22.4 Coordination compound structures can very geometrically. Molecules with the same chemical formula but different geometric structures are isomers.
  • Structural isomers
    • Coordination isomers occur when it is possible to exchange a coordinated ligand and the uncoordinated counter ion, as with [Co(NH₃)₅Br]SO₄ and [Co(NH₃)₅SO₄]Br.
    • Linkage isomers occur when the ligand can be attached to the metal through different ions. For example, thiocyanate (SCN-) contains sulfur and nitrogen, each with a lone pair, either of which can be used to bind to a metal ion to form a coordination compound.
  • Geometric isomers
    • Cis-trans isomers involve complexes where ligands of similar types may be on the same side or opposite sides of the central metal ion. The chemical properties of cis and trans forms may be radically different.
    • Fac and mer isomers involve ligands which form cube units with components on the corners (fac) or in the middle of the face (meridian or mer).
  • Optical isomers form when a central metal ion binds to three or more ligands, each of which has at least two binding sites. Geometrically, the coordination compound can have a mirror-image. Complexes with this property are chiral.
• 22.5 Two theories are used to explain bonding in coordination compounds. we are already familiar with molecular orbital theory which explains bonds as overlapping π and σ orbitals between atoms, but it does not account for all observed phenomena. Ligand field models may be used to explain ligand bonds in terms of electrostatic attraction and repulsion and electron spin within orbitals (d-orbital splitting), to account for slight differences in energy levels that affect bond strength, conductivity, and magnetic properties.
• 22.6 The colors of coordination compounds may also be explained in terms of de-orbital splitting. Where d-orbital separation Δ₀ is large, the complex is able to absorbe a large amount of energy in a single photon; therefore those complexes with the greatest orbital splitting absorb light with the lowest wavelengths (highest frequency, greatest energy).

Read the following weblecture before chat: Transition Elements and their Characteristics

Study Activity

Chat Preparation Activities

• Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

Chapter Quiz

• Required: Complete the Mastery exercise with a passing score of 85% or better.
• Go to the Moodle and take the quiz for this chapter.

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(Aligns to) AP LAB #18 GUIDED INQUIRY — — GUIDED INQUIRY — Titration quantitative analysis methods — Phase I

Choose two different common household chemicals such as a food juice, vinegar, or cleaning solution. Select an appropriate method to measure the expected pH range, and design a procedure to analyze of the acidity of your items, (e.g., using titration acid-base or redox methods). Resources:

• APGIE Investigation 4: How much acid is in Fruit Juices and Soft Drinks
• APGIE Investigation 3: What Makes Hard Water Hard?
• IGHCE Lab 20.1 Quantitative Analysis of Vitamin C
• AP2009 8 Determination of Concentration by oxidation-reduction reactions

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