Question

Hydrogen bonds are formed between moleculcs in which hydrogen is covalently bonded to an clcment whose atomic radius and electroncgativity respectively are (1) large and low (2) large and high (3) small and high (4) small and low

Short answer

The correct answer is (3) small and high.

Step-by-step solution

Understand the Concept of Hydrogen Bonding

Hydrogen bonds occur when a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen, nitrogen, or fluorine, is attracted to another electronegative atom. This gives rise to a weak bond called a hydrogen bond.

Determine Characteristics for Hydrogen Bonding

Identify the properties of the element to which hydrogen is bonded: it should have a small atomic radius and high electronegativity. These characteristics facilitate strong attraction forces that are necessary for forming hydrogen bonds.

Analyze the Given Options

Evaluate each of the given choices based on the properties identified in Step 2: 1) Large radius and low electronegativity does not support hydrogen bonding. 2) Large radius and high electronegativity does not support hydrogen bonding. 3) Small radius and high electronegativity supports hydrogen bonding. 4) Small radius and low electronegativity does not support hydrogen bonding.

Select the Correct Answer

Based on the analysis, the correct property combination for an element that forms hydrogen bonds is small atomic radius and high electronegativity.

Key concepts

Hydrogen Bonds

Hydrogen bonds are a type of weak chemical bond that forms between molecules. They occur when a hydrogen atom is covalently bonded to a highly electronegative atom, such as oxygen (O), nitrogen (N), or fluorine (F). This creates a partial positive charge on the hydrogen, which can be attracted to a neighboring electronegative atom with a partial negative charge.

This interaction results in a bond that is weaker than covalent or ionic bonds but still significant enough to influence the properties of molecules. Hydrogen bonds are crucial in biological systems. For example, they play a key role in the structure of DNA and proteins, helping to maintain their shapes and functionalities. Understanding how hydrogen bonds work helps explain why water has such unique properties, like high surface tension and the ability to dissolve many substances.

Electronegativity

Electronegativity is a measure of how strongly an atom can attract and hold onto electrons. It is a key concept in understanding chemical bonding, especially hydrogen bonds. Atoms with high electronegativity, like nitrogen, oxygen, and fluorine, have a strong ability to attract electrons.

• This makes the molecule more polar, as the electronegative atom pulls the shared electrons closer to itself.
• This creates a partial negative charge on the electronegative atom and a partial positive charge on the hydrogen atom involved in the bond.

The difference in electronegativity between atoms can influence how molecules interact with each other. For hydrogen bonds, the larger the difference in electronegativity between the hydrogen and the atom it's attached to, the stronger the hydrogen bond will be. This property explains why hydrogen bonds only form when hydrogen is bonded to highly electronegative atoms.

Atomic Radius

Atomic radius is the distance from the nucleus of an atom to the outermost electron shell. It generally decreases as you move across a period in the periodic table and increases as you move down a group.

A smaller atomic radius allows atoms to come closer together, which is essential for forming hydrogen bonds because:

• The closer proximity allows stronger interactions between the positive charge on the hydrogen atom and the negative charge on the electronegative atom.
• This close distance maximizes the attraction force and stabilizes the hydrogen bond.

To form a strong hydrogen bond, the element that hydrogen is bonded to should have both a small atomic radius and high electronegativity. This combination ensures a strong attraction, producing stable and effective hydrogen bonds commonly seen in water, DNA, and various organic molecules.