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Ionic vs. Molecular Compounds

Ionic vs. Molecular Compounds. Bonding and Physical Properties. Vocabulary Used to Describe Physical Properties. Intermolecular Forces : the forces of attraction that hold particles together. Image Reference: itl.chem.ufl.edu. Solubility: The ability to dissolve in water.

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Ionic vs. Molecular Compounds

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  1. Ionic vs. Molecular Compounds Bonding and Physical Properties

  2. Vocabulary Used to Describe Physical Properties • Intermolecular Forces: the forces of attraction that hold particles together. Image Reference: itl.chem.ufl.edu

  3. Solubility: The ability to dissolve in water. • Water surrounds the ions and pulls them apart. Picture reference: elmhurst.edu

  4. Conductivity: The ability to carry a charge. Requires moving ions to carry the current. Picture reference: chemistryland.com

  5. Malleability: The ability of metals to be hammered into different shapes

  6. Ductility: The ability of metals to be drawn into wires.

  7. Properties of Ionic vs. Molecular Compare and Contrast

  8. Ionic Bonds & Ionic Compounds • Ionic Compounds – compounds of cations & anions • Metal cations + nonmetal anions • Electrically neutral • (+) and (-) charges are equal

  9. 7.2 Ionic Bonds & Ionic Compounds • Ionic Bonds – Electrons are TRANSFERRED to the element with higher electronegativity. Electrostatic forces then hold ions together in ionic compounds • Example - NaCl

  10. Molecular Compounds • Molecule – atoms joined by covalent bonds (neutral charge) • Electrons are SHARED between two atoms (not always equally: ex: polar) • Diatomic – made of 2 atoms

  11. Element Types and Bonds Picture reference: mchemwiki.ucdavis.edu

  12. Compare and Contrast Ionic vs. Molecular Compounds Based on Physical Properties

  13. Physical State of Matter • Ionic: Mostly Solid due to strong intermolecular forces holding it together • Molecular: Variable

  14. Intermolecular Forces • Ionic: Very Strong. Hold particles together • Molecular: Variable. Depends on substance

  15. Melting and Boiling Points Energy is required to overcome intermolecular forces and change state of matter. Reference: chem4kids.com More Energy = Higher Melting/Boiling Points = Stronger intermolecular forces

  16. Melting and Boiling Points • Ionic: Strong IMF means higher melting and boiling points • Molecular: Weaker IMFs means lower melting and boiling points Picture Reference: wyckoffps.org

  17. Solubility: Like Dissolves Like • Ionic: More soluble because IONS are present. Ions are POLAR “like” water • Molecular: No ions present, so most are not easily dissolved in water. More likely to clump

  18. Conductivity Ionic Compounds: Able to carry a charge when dissolved or melted (moving ions) NOT IN A SOLID Molecular (water) Compounds: No moving ions so not conductive

  19. Crystalline • Ionic: highly organized crystalline structure from arrangements of ion particles

  20. Crystalline • Molecular: Tend to be branched, long chains or circular. Very little crystal formation present. Picture reference: eoearth.org

  21. Ionic vs Molecular Compounds

  22. What about metals? Metals are elements, not compounds, but they have a unique bond arrangement

  23. Bonding in Metals • What property of metals makes them good electrical conductors? Metal bonding involves highly mobile electrons, which are shared by all the nuclei in solid metal. The movement of the electrons accounts for the high electrical conductivity.

  24. Metallic Bond • Consists of the attraction of the free-floating valence electrons for the metal cations • Forces of attraction hold metals together

  25. What are metals made up of? • Closely packed cations • Mobile valence electrons (that drift around cations)‏ http://www.docbrown.info/page04/4_72bond/mb1.gif

  26. Sea of Electrons Model http://www.geo.arizona.edu/xtal/nats101/9_4.jpg

  27. Properties of Metals • All properties of metals are described by sea of electrons model (all due to mobility of electrons)‏ • Good conductors of electricity • Ductile (they can be drawn into wires)‏ • Malleable (they can be hammered into sheets or forced into shapes)‏

  28. Metallic vs. Ionic Bonding • In Metallic Bonds the electrons are mobile so the shapes of metals can be changed • In Ionic bonding the electrons are arranged in a crystal structure and if forced to move would shatter because like charge ions would repel each other when moved

  29. Bonding in Metals • Metals are ductile

  30. Alloys • Defined as homogeneous mixtures (or solutions) composed of at least 1 metal (can include nonmetals as well)‏ • Facts: • Most metallic item used daily are alloys, they are not pure metals.

  31. Alloys • Alloys are made by a process of melting down and cooling a mixture of metals • Alloys are superior to pure metals • Pure metals are often softer than alloys http://www.directcarparts.co.uk/images/alloys3.jpg

  32. Types of Alloys • Brass • Combination of copper and zinc http://www.directdoorhardware.com/Brass_Accents/Hardware_Finishes/PolishedBrass_500.jpg http://www.germes-online.com/direct/dbimage/50137626/Double_Locking_Brass_Padlock.jpg http://www.raisonsbrassband.com/images/Bugle.jpg

  33. Types of Alloys • Bronze • 7 parts copper to 1 part tin • Harder than copper used in coins http://www.u-handbag.com/images/bronze-snaps.gif http://www.saint-petersburg.com/images/monuments/bronze-horsemen.jpg

  34. Types of Alloys • Steel • Mostly made up of iron and carbon (but also B, Cr, Mn, Mo, Ni, W, V)‏ http://www.turkeyfryerexpress.com/images/BC1102.jpg http://ocw.mit.edu/NR/rdonlyres/Global/6/695E8EC6-5161-4B05-B6F1-8BE09DC40F68/0/chp_steel_struct.jpg

  35. Types of Alloys • Sterling Silver • 92.5% silver and 7.5% copper • Harder and more durable than elemental silver, but soft enough to be made into jewelry http://www.cheapwholesalejewelry.com/shop/images/sparkle%20sterling%20silver.jpg

  36. Types of Alloys • GOLD and Jewelry Alloys • Gold and other metals http://www.stillwaterpalladium.com/images/heraeus_dental1.jpg http://www.handwovenbands.com/images/14k18k.jpg

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