QUESTION: Which of the following has the highest electronegativity? A. Na, B. Br, C. F Electronegativity is a measure of the tendency of an atom to attract shared electrons. When atoms share electrons, the electrons are “polarized” towards the more electronegative atom. General trend in electronegativity follows that of ionization energy. Across a period: Left to right: increasing Going up a group: increasing SCRIPT: Which of the following has the highest electronegativity? A. Na, B. Br, C. F PAUSE CLICK Electronegativity is a measure of the tendency of an atom to attract shared electrons. CLICK When atoms share electrons, the electrons are generally not shared equally. We say that the electrons are polarized towards the more electronegative atom. The general trend in electronegativity follows that of ionization energy. Across a period, from left to right, and going up a group, electronegativity increases. Here’s a periodic table. CONTINUED ON NEXT SLIDE

increasing increasing increasing Here’s sodium CLICK Here’s bromine CLICK And here’s fluorine. CLICK Going up a group, the trend in electgronegativity is increasing. Therefore, flourine is more electronegative than bromine CLICK And lithium, which is just above sodium, is more electronegative than sodium. Across a row, the trend from left to right is increasing… CLICK Therefore, fluorine is more electronegative than lithium, … which is more electronegative than sodium. Therefore, of the three elements given, the most electronegative is fluorine. In fact, Fluorine is the most electronegative element…. CALLOUT “F is the most electronegative element: 4.0” And it is assigned a value of 4.0 in Linus Pauling’s electronegativity scale… So we could say that that the trend in electronegativity is increasing towards flourine. If you’re wondering about the noble gases, they are generally found as a collection of isolated atoms in nature. They tend not to gain, lose, or share electrons. When Pauling created the electronegativity scale, no data was available to assign values for the noble gases. Since then, however, Xenon and fluorine have been found to form molecules under certain laboratory conditions, and spectroscopic data suggest that Neon has a higher electronegativity than fluorine, and that Helium has a higher electronegativity than neon. Therefore, theoretically, helium has the highest electronegativity. But when asked on an exam which atom has the highest electronegativity, your answer should be fluorine. PAUSE END RECORDING Across a period: Left to right: increasing Going up a group: increasing

QUESTION: Which of the following has the highest electronegativity? A. Na, B. Br, C. F

Video ID: 3-1-1 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08