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### diatomic elements

Posted: Thu Oct 04, 2018 11:55 pm
Hi! Can someone explain to me why diatomic elements form, and how to distinguish between whether an element is existing in its diatomic form or not? For example, if a problem involves a diatomic element like oxygen, do you assume that's in a diatomic form, or does the problem have to state explicitly "oxygen gas"?

### Re: diatomic elements

Posted: Fri Oct 05, 2018 12:07 am
All the elements in the acronym HOFBrINCl, (hydrogen, oxygen, fluorine, Bromine, Iodine, and chlorine) are included in the diatomic elements. Any time these elements are listed in a chemical equation they must have the subscript of 2 as you always assume they are diatomic.

### Re: diatomic elements

Posted: Fri Oct 05, 2018 5:10 am
The reason these elements are diatomic is because they don't have enough electrons to fill up their valence shells. Thus, they cannot exist as a single atom.

### Re: diatomic elements

Posted: Fri Oct 05, 2018 5:17 am
One cheap mnemonic device to remember these is: Never Have Fear Of Ice CoLd Bread
Never: $N_2$ Nitrogen
Have: $H_2$ Hydrogen
Fear: $F_2$ Fluorine
Of: $O_2$ Oxygen
Ice: $I_2$ Iodine
CoLd: $Cl_2$ Chlorine
Bread: $Br_2$ Bromine

### Re: diatomic elements

Posted: Fri Oct 05, 2018 9:16 am
My TA taught us another method to remember the diatomic elements. She refers to them as gens and ines. Ex. HydroGEN and fluorINE

### Re: diatomic elements

Posted: Fri Oct 05, 2018 9:35 am
For me, it helps when I picture them on the periodic table because, with the exception of Hydrogen, the other six elements (C, N, O, F, Cl, Br, I) border the top right hand corner of the table next to the column of noble gases.

### Re: diatomic elements

Posted: Sun Oct 07, 2018 7:53 pm
In high school, we learned to remember them with a phrase pronounced "Br-inkl-hoff," which is Br(bromine), I(iodine), N (nitrogen), Cl(chlorine), H(hydrogen), O(oxygen), and F(fluorine). Helped me a lot back then and now.

### Re: diatomic elements

Posted: Sat Oct 13, 2018 8:33 pm
Some elements exist as diatomic elements since in their original state, their valence shells are not filled, thus they share electrons between each other and thus fill their shells and achieve a state of lower energy.

### Re: diatomic elements

Posted: Sat Oct 13, 2018 8:54 pm
Diatomics exist to share electrons covalently and achieve a lower energy state.

HOFBrINCl is a metonym to remember the diatomics:
H- Hydrogen
O- Oxygen
F- Fluorine
Br- Bromine
I- Iodine
N- Nitrogen
Cl- Chlorine

### Re: diatomic elements

Posted: Sat Oct 13, 2018 9:01 pm
Does anyone know what order to put the elements in when writing an empirical formula?

### Re: diatomic elements

Posted: Sun Oct 14, 2018 2:50 pm
Karina Jiayu Xu 4E wrote:Does anyone know what order to put the elements in when writing an empirical formula?

In an empirical formula, it's typically C, H, and then other elements follow in alphabetical order.

### Re: diatomic elements

Posted: Mon Oct 15, 2018 1:45 am
Diatomic elements only need to exist in pairs of atoms when they are standing alone. For instance, in OH-, you wouldn't need two hydrogen atoms because the hydrogen is not free standing. However, if you have hydrogen gas, you would need H2 because it is not attached to a different element.

### Re: diatomic elements

Posted: Thu Nov 15, 2018 11:05 pm
Elements are diatomic because their valence shells aren't completely filled by electrons; therefore, electrons are shared a lower energy state is achieved.