What is electronegativity: some theory
In complex compounds consisting of atoms of different elements, the electron density will always be shifted to one, the most "strong" neighbor. For example, in a water molecule (H2O) the winner will be oxygen, and in hydrochloric acid (HCl) the duel will win a chlorine atom. How to learn to determine this force? For this it is enough to disassemble what electronegativity is. Let's get started
Atoms and elements
The first thing to learn is the difference between an atom and an element. For example, in the HNO molecule3As many as five atoms and only three elements, which are hydrogen (H), nitrogen (N) and oxygen (O). If the name of some icon or symbol is erased from memory, then the periodic system of Mendeleev will come to the rescue.It lists all the elements that exist today. So, the first difficulty is overcome. Let's get closer to the question of what is electronegativity.
In schools and universities, the Pauling scale will suffice to reveal the strongest atom that will pull the electron density of the weaker “neighbors” onto itself. Do not be afraid.Everything is very simple here. The relative electronegativity of chemical elements is arranged in ascending order and varies in the range of 0.7-4.0. The logic here is clear: for whom this value is greater, that is even stronger.The value "0.7" belongs to the most active metal - France. Here he loses to absolutely everyone, that is, he is the least electrically negative (the most electropositive). The maximum value of four, boasts fluoride. Therefore, he has no equal in strength.
Even without really understanding what electronegativity is, in any complex fluorine-containing compound, one can immediately determine the winner. Who will pull away electron density in lithium fluoride (LiF)? Of course, fluoride. Which element is more electronegative in the molecule of silicon tetrafluoride (SiF4)? Of course, again fluoride.
We fix passed
So, having analyzed what electronegativity is, let's back up the theory with examples. Learn to identify the strongest element in the mix. Take a molecule of sulfuric acid (H2SO4). Using the Pauling scale, we determine the relative electronegativity of all three required elements.In hydrogen, it will be 2.1. The value for sulfur is slightly higher - 2.6. But the clear leader will be oxygen, having a maximum rate of 3.5. Hence, the most electronegative element in the molecule H2SO4it will be oxygen. Thus, it is possible to determine the electronegativity value of any element.