CHEM 3750 Lecture 1: Chapter1

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lavenderoyster394

24 Aug 2016

School

University of Guelph

Department

Chemistry

Course

CHEM 3750

Professor

France- Isabelle Auzanneau

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Document Summary

Atomic nuclei with odd mass numbers have angular momentum and behave as though they were spinning on an axis, that is, they behave as a tiny magnet. In the absence of an applied field, these tiny magnets are randomly oriented, but when they are put in the presence of an applied magnetic field (ho), they will align with or against that field. A slight excess will align with the field ( -spin) while the others will be anti parallel ( -spin). (cid:149) 1h has a spin quantum number i = 1/2 and has allowed spin states of +1/2 or -1/2. 1 (cid:149) other nuclei with i = 1/2 are 13c, 19f and 31p and these also respond to an external magnetic field (cid:149) the nuclei of nmr-active nuclei behave like tiny bar magnets (cid:149) These concepts apply to 1h, 13c, and 19f nuclei which have spin quantum numbers of.

Related Questions

NMR (nuclear magnetic resonance) Uses the same theory and technology as an MRI!

1-What is the source of energy in NMR?____________________________________ What happens to atoms in a molecule exposed to this energy?_______________________________

2-What are two atom types that can be observed by NMR?________________________

3-What units are used to measure the strength of the magnetic field used?____________________ More significantly for us, what units are used to indicate the frequency of radiation used for resonance?________________

(Our instrument downstairs (a picoSpin) is 45 MHz. At the MN NMR Center at the U, they have instruments ranging 500 â 900 MHz.)

4-What can be distinguished with NMR?______________________________________________________

5-What are the axes of an NMR spectrum?____________________________________________________

6-What are the four different features of a spectrum that can provide information?

7-The number of NMR signals in a spectrum is equal to what?___________________________________

8-The position of an NMR signal in a spectrum depends on the electronic environment surrounding a particular __________________________.

9-If a proton is attached to an electronegative atom, it absorbs (downfield or upfield).

10-Where in an NMR spectrum would we expect to see an aldehyde H? See Table 14.1 ________________

11-What information is given by the area under an NMR signal?____________________________________

12-What information about is given by spin-spin splitting?________________________________________

13-How many peaks are contained in an NMR signal that has been described as a triplet?_________________________ How many adjacent protons are splitting this signal?________________

Skipping to section 14.11â¦

14-What do the number of different signals in a ¹³C spectrum indicate? __________________________________

15-What is the range of chemical shifts in a ¹³C spectrum?______________________________________________

CHEM 3750 Lecture 1: Chapter1

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