M3_4-mod-student - Unit 4 How do we predict properties?...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemistry XXI Unit 4 How do we predict properties? Module 2: Characterizing Ionic Networks and Metallic Substances Central goal: To explain and predict the physical properties of metals and of ionic compounds based on the charge and size of the ions present in the system.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chemistry XXI The Challenge Metals can chemically react with nonmetals to form new chemical compounds. In most cases, these compounds are not comprised of molecules, but of ions arranged in solid crystalline networks . Modeling How do I predict it? How can we make predictions about the composition of these ionic compounds? How can we predict what properties they may have?
Background image of page 2
Chemistry XXI Nonmetals Important Differences In general, atoms of nonmetals have higher ionizations potentials and electronegativities ( χ ) than those of metals. Thus, nonmetals have a higher affinity for electrons than metals. Metals
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chemistry XXI From Polar to Ionic The larger the difference in electronegativity ( ∆ χ ) between bonding atoms the more polar the bond. For ∆ χ > ~1.7 , the bonding electrons spend most of their time close to the nonmetal atom.
Background image of page 4
Chemistry XXI The properties of the compounds that results from the reaction of metals with nonmetals are better described assuming that independent ions are formed. Ionic Compounds Metal + ion ( cation ) Nonmetal - ion ( anion )
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chemistry XXI Ionic Networks + and - ions interact with all other ions in the system, and they do not form molecules. They arrange into a crystalline network . NaCl For these compounds, the chemical formula only indicates the ratio of + to ions in the lattice ( 1 : 1 ).
Background image of page 6
Chemistry XXI FCC Crystal Structures BCC Different ionic compounds may have different crystal structures. NaCl CsCl Every type of crystal lattice can be built by repeating a characteristic UNIT CELL .
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Let’s Think Ionic compounds do not conduct electricity as solids, but they do it when melted. Solid ionic compounds shatter when struck. How would you
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/09/2009 for the course CHEM 151 taught by Professor Staff during the Fall '08 term at University of Arizona- Tucson.

Page1 / 31

M3_4-mod-student - Unit 4 How do we predict properties?...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online