Answer:
The correct answer is (4) I and F
Explanation:
The covalent bond is the chemical bond between atoms where electrons are shared, forming a molecule. Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and chlorine Cl. These elements have many electrons in their outermost level (valence electrons) and have a tendency to gain electrons to acquire the stability of the electronic structure of noble gas. The shared electron pair is common to the two atoms and holds them together.
The covalent bond between two atoms can be polar or nonpolar. If the molecule composed of two atoms of the same element is considered, a pair of electrons is shared that is attracted with the same intensity by the two nucleos. So the bond is non polar. However, when different atoms are linked, this bond will not always be performed symmetrically. Then this bond will be polar, and depends on the difference in electronegativity of the elements that bind (Electronegativity is called the tendency that the atom of a given element presents to attract electrons). The greater the electronegativity difference, the greater the polar character the bond has. The most electronegative element will be the one that attracts the shared electrons with more force, then a negative partial charge will be generated on said element, while in the other element (less electronegative) a positive partial charge will be generated.
First, to determine the link with greater polarity it is convenient to know the electronegativity of each element:
- Br: 2.8
- Cl: 3.0
- F: 4.0
- I: 2.5
Knowing the electronegativity of each element, it is possible to determine the electronegativity difference of each bond:
- Br and Cl: 3.0-2.8=0.2
- Br and F: 4.0-2.8=1.2
- I and Cl: 3.0-2.5=0.5
- I and F: 4.0-2.5=1.5
The bond between iodine I and fluorine F have the greatest electronegativity difference, indicating that this bond is the one with the highest polarity.
As the fluorine has greater electronegativity, the shared electrons are attracted more strongly by this element and a negative partial charge is generated on the fluorine. And in the iodine a positive partial charge is generated.
So, the correct answer is (4) I and F
