This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
NaCl NaCl has an ionic bond-look at the EN difference.
Na = 0.9
Cl = 3.0
ΔEN = 2.1
Take home lesson: Polar bonds are those with a Δ EN >0. Note that IONIC bonds are VERY POLAR bonds--as polar as you can get!!
Table 5.3 lists the electronegativities of many representative elements.
Polarized bonds allow hydrogen bonding to occur.
A hydrogen bond is an electrostatic attraction between an atom bearing a partial positive charge in one molecule and an atom bearing a partial negative charge in a neighboring molecule. The H atom must be bonded to an O, N, or F atom.
Hydrogen bonds typically are only about one-tenth as strong as the covalent bonds that connect atoms together within molecules.
H–bonds are intermolecular bonds. Covalent bonds are intramolecular bonds. Professor Alton J. Banks
Is Hydrogen bonding of concern to Joe and Jane Q. Public?
Here’s one example:http://pubs.acs.org/cen/email/html/cen_86_i41_8641notw4.html
Here’s a blowup of the molecule--and the resulting solid which is frequently fatal to animals:
Are there other significant properties associated with Hydrogen bonding? - Boiling Points are higher than expected based upon the molecular weight.
-Surface Tension:It’s why raindrops are spherical in shape! -----and why “water striders” float on the surface of water. --What happens when we disrupt the surface tension?
- Large heat capacity: DEFINITION: Amount of heat energy required to change the temperature of 1 g of water by 1˙C.
Maximum Contaminant Level Goal (MCLG) and Maximum Contaminant Level (MCL)
TABLE 5.10
MCLG: The level at which a 70kg (154 lbs) person could drink 2L of water with this contaminant level every day for 70 years without suffering ill effects.
Water flows from the region of higher concentration (of water) to one of lower concentration. Result is that level of water rises (in right side of container). This is one major mechanism for the rise of water in the xylem of plants/trees.
Access to safe drinking water varies widely across the world
Professor Alton J. Banks
So how does hydraulic fracturing affect the water issue? The 2012 legislative session of the North Carolina General Assembly concluded with legalization of hydraulic fracturing and horizontal drilling for exploration and development of shale gas in North Carolina. Over the past year, North Carolina legislators, policy makers, scientists, independent experts, local governments, state environmental and commerce agencies, and a variety of other stakeholders have studied and debated the potential for shale gas development in North Carolina and potential enabling legislation for hydraulic fracturing and horizontal drilling. This process concluded on July 2, 2012, when the General Assembly voted to override a gubernatorial veto of the enabling legislation, Senate Bill 820 also known as the Clean Energy and Economic Security Act (the “Act”).
This process began in June 2011, when the General Assembly directed the North Carolina Department of Environment and Natural Resources (“DENR”), the Department of Commerce, and the Department of Justice to “study the issue of oil and gas exploration in the State and the use of directional and horizontal drilling and hydraulic fracturing for that purpose.”[1] Further, the 2011 law directed DENR and the other agencies to evaluate the potential shale resource in North Carolina and methods of natural gas extraction and to conduct an analysis of potential economic impacts, environmental impacts, social impacts, consumer protection issues, infrastructure issues, as well as potential oversight and administrative issues related to shale gas development in North Carolina.
These agencies completed the comprehensive study and published the report, North Carolina Oil and Gas Study under Session Law 2011-276, on April 30, 2012. Most notably, the report concluded that “After reviewing other studies and experiences in oil and gas-producing states, DENR has concluded that information available to date suggests that production of natural gas by means of hydraulic fracturing can be done safely as long as the right protections are in place. Production of natural gas by means of hydraulic fracturing can only be done safely in North Carolina if the state adopts adequate safeguards in the form of regulatory standards specifically adapted to conditions in the state and invests sufficient resources in compliance and enforcement.”[2] In light of the DENR report, legislators introduced the Act, when the 2012 legislative session convened in May to legalize hydraulic fracturing and horizontal drilling.