Question

Identify the compound with the smallest percent ionic character. identify the compound with the smallest percent ionic character. hf co ibr lif n2

Answer 1

 I'll try. A purely ionic bond, as the name implies is a bond between ions. If that sounds like double-talk it's because some ionic compounds are more ionic than others. A purely covalent compound is one in which the electrons are shared EQUALLY. It turns out that the only compounds in which the electrons are shared equally is one in which both atoms sharing the electrons are of the same element. For example O2, N2, Cl2, I2 or F2. Now suppose you make a compound between Fluorine and Iodine, IF. Since fluorine has a greater attraction for electrons than iodine, the bond will be polar. That is the fluorine part of the molecule will be negative and the iodine part will be positive. The attraction for electrons isn't equal. The same thing happens with ionic bonds. In your first question, the ionic character decreases from NaF through SiF4. Sodium loses an electron quite readily because it achieves a stable neon like configuration. Fluorine attracts an electron very strongly for the same reason. But as you move across the period, two things are happening. First, look at SiF4. Silicon is right in the middle of the period, It can achieve a stable inert gas configuration either by gaining 4 or losing 4 electrons. So it depends upon the electronegativity (the electron grabbing ability) of the atom it's combining with. Since Fluorine has the highest electron grabbing ability of any of the reactive elements, it will tend to pull the electrons away from silicon. But silicon doesn't completely give them up as it would in a purely ionic compound. AlF3 is similar but will tend to give up 3 electrons a little easier than SiF4. MgF2 is even more ionic because it's approaching an inert gas configuration and only need to lose 2 electrons. Can you see what's happening? The closer you get to the middle of a period, the less likely an atom is to give up COMPLETELY its electrons. In question 2 your answer is CO. The elements are close together (which means that their electronic structure is similar) and carbon, like silicon is in the middle of the period so its more likely to share electrons than it is to give them up (form an ionic bond). So it turns out that most chemical bonds are neither completely ionic or covalent but lie in between the two extremes and are called polar covalent. I hope this helps.