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    Why in an ammonium ion, why does hydrogen lose the electron and therefore have a dative coordinate bond rather than nitrogen losing an electron and therefore there would be no dative bond?
    Also, when drawing dot and cross structures, how do you know which element is in the centre?
    Thanks
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    (Original post by Laraib Chaudhry)
    Why in an ammonium ion, why does hydrogen lose the electron and therefore have a dative coordinate bond rather than nitrogen losing an electron and therefore there would be no dative bond?
    Also, when drawing dot and cross structures, how do you know which element is in the centre?
    Thanks
    The NH3 consists of three hydrogens bonded to a nitrogen. There is a lone pair of electrons on the nitrogen which decreases the bond angle between the hydrogen atoms. Providing a more suitable environment in which a hydrogen ion bonds to the nitrogen's lone pair with the aid of an electrostatic attraction between the valence (outer) electrons of nitrogen and the protons of the hydrogen ion to gain a full outer shell of electrons, thus making the hydrogen ion more stable. You just need to know that hydrogen ions bond to the NH3 (I assume ur doing A-levels?). Doing exam practice on dot and cross diagram question will definitely help, you should be fine if you keep practising.

    When drawing dot and cross diagrams, the element in the centre is usually the less electronegative one, there is an exception with water however, where oxygen is more electronegative than hydrogen. The more electronegative elements are found in the top right of the periodic table, the least are in the bottom left.

    I hope this helps, if there are any other questions please ask
 
 
 

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