Oxygen and Electronegativity

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Oxygen and Electronegativity

Postby AMahadi » Sat Nov 02, 2019 3:16 pm

Why does oxygen have a high electronegativity and what does that indicate?

Ronak Naik
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Re: Oxygen and Electronegativity

Postby Ronak Naik » Sat Nov 02, 2019 3:34 pm

Oxygen only needs two more electrons to fill its valence shell and therefore it means that it has a high power to attract electrons in order to complete its final energy shell. Fluorine is the most electronegative atom since it only requires one more to fill its shell.

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Re: Oxygen and Electronegativity

Postby JasonLiu_2J » Sat Nov 02, 2019 3:36 pm

The trend for electronegativity is that it increases up a group and from left to right across a period. Since oxygen is towards the upper right of the periodic table, it has a high electronegativity. This can also be explained conceptually when you consider an oxygen atom. An oxygen atom is small, which means its valence electrons are relatively close to the nucleus and the positive nucleus exerts a greater force of attraction on these electrons. Furthermore, oxygen is only two electrons away from a noble gas configuration, so it would want to gain electrons to achieve this. When you consider these characteristics, you can see that oxygen would have a high electronegativity and would be more likely to attract electrons towards it (Exerts a greater pull on other electrons). Thus, in a molecule such as CO, the shared electrons would actually be slightly more attracted towards the oxygen as opposed to the carbon, which leads to partial negative and partial positive charges. Hope this helps!

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Re: Oxygen and Electronegativity

Postby AKhanna_3H » Sat Nov 02, 2019 3:37 pm

Electronegativity is a measure of the tendency of an atom to form a covalent bond. Fluorine is the most electronegative atom on the periodic table, meaning it has the highest tendency to form a covalent bond. Since Oxygen is close to Fluorine, it also has a relatively high electronegativity. Electronegativity increases going across a row and decreases going down the columns of the periodic table. Hope that helps!

Sofia Q
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Re: Oxygen and Electronegativity

Postby Sofia Q » Sat Nov 02, 2019 3:58 pm

Hi! I thought that maybe it can be helpful to see it visually.

Considering that valence electrons are those found within the s and p subshells added together. A noble gas such as neon ([He] 2s2 2p6) has both their s and p orbitals filled, meaning 2 + 6= 8. This makes it stable and have a low electronegativity. (draw it with the arrow diagram, too!)

Now, oxygen's electron configuration is [He] 2s2 2p4, add the s and p and you get 2 + 4= 6, meaning it needs 2 more to have its octet and be stable as neon is. It has high electronegativity because of the pull it has on other electrons in the search to fill up its p subshell. You can also remember it by saying that it is easier for oxygen to take electrons rather than give them because it is so close to the full octet.

Something interesting we walked about in the 3 hour review session on Friday, is that by looking at the periodic table one would assume nitrogen to be less electronegative than oxygen following the trend on the periodic table, but that in fact due to the symmetry that the nitrogen atom has in the 2p subshell, more clearly seen in a arrow diagram, gives it a higher electronegativity than oxygen despite having one more electron!

Edmund Zhi 2B
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Re: Oxygen and Electronegativity

Postby Edmund Zhi 2B » Sat Nov 02, 2019 4:08 pm

Elements such as Oxygen and Fluorine in the upper right hand corner of the periodic table exhibit high electronegativity because
1) Basically, they are really close to filling their valence shell (the 2p orbitals)
2) Increased electrostatic attraction to the nucleus due to more protons than the elements to their left
3) Increased Zeff(effective nuclear charge) due to the fact that the valence shell is in the 2nd energy level, so there is not as much shielding going on as there is in the elements below Oxygen and Fluorine.

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