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Which of the following bolded atoms is a hydrogen bond pair donor?
1) $H - O -$
2) $- C - H$
3) $- N - H$
4) $H - H$
Answer (1)
Hydrogen bond donors have hydrogen atoms bonded to highly electronegative atoms like oxygen or nitrogen.
Examine each option to see if it fits this criterion.
Options 1 ( H − O − ) and 3 ( − N − H ) have hydrogen atoms bonded to oxygen and nitrogen, respectively.
Therefore, the hydrogen bond donors are options 1 and 3.
Explanation
Understanding Hydrogen Bond Donors We need to identify which of the given molecules can act as a hydrogen bond donor. A hydrogen bond donor is a molecule containing a hydrogen atom bonded to a highly electronegative atom such as oxygen (O) or nitrogen (N).
Analyzing Each Option Let's examine each option:
H − O − : The hydrogen atom is bonded to an oxygen atom, which is highly electronegative. Therefore, it can be a hydrogen bond donor.
− C − H : The hydrogen atom is bonded to a carbon atom. Carbon is not electronegative enough to make this a good hydrogen bond donor.
− N − H : The hydrogen atom is bonded to a nitrogen atom, which is highly electronegative. Therefore, it can be a hydrogen bond donor.
H − H : The hydrogen atom is bonded to another hydrogen atom. Neither is electronegative enough to make this a hydrogen bond donor.
Identifying the Donors From the analysis, options 1 and 3 can act as hydrogen bond donors.
Final Answer The question asks which of the bolded atoms is a hydrogen bond donor. Options 1 and 3 contain hydrogen atoms bonded to electronegative atoms (oxygen and nitrogen, respectively), making them hydrogen bond donors.
Examples
Hydrogen bonding is crucial in many biological systems. For example, it is responsible for the structure of water, which is essential for life. Hydrogen bonds also hold the two strands of DNA together, allowing for genetic information to be stored and replicated. In proteins, hydrogen bonds help to fold the protein into its correct three-dimensional shape, which is necessary for its function.
