All Junior Cert Science Revised Syllabus posts
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    ionic and covalent Sarah2014

    can someone explain to me what these terms mean? thanks

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      Ionic bonding is where an atom gives away electrons to another atom in order to make sure that both atoms have a full outer shell.

      Covalent bonding is where an atom shares electrons with another atom.

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      An example of Ionic bonding is Sodium Chloride, or NaCl. Sodium has 11 Electrons, 2 in the first shell, 8 in the second and 1 in its outer shell. Chlorine on the other hand has 17 Electrons. 2 in its first shell, 8 in the second and 7 in the outer shell. Both of these elements 'want' a full outermost shell, which is why when bonded sodium gives chlorine the electron in its outer shell, cancelling it out and leaving it with a full outer shell, but still remaining Sodium in the form Na- (the minus indicating its lost an electron) and Chlorine receives this electron, giving it a full outer shell, but yet again it still remains Chlorine in the form Cl+ (the plus indicating its gained an electron from Sodium)

      I hope this helps, as for Covalent bonding I can also explain that with an example like I have above with Ionic if its needed. ;)

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      ^ Jesus some of that is very complicated.

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      thanks @EH458 that example helped a lot :)

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      ^ Did it help in any way though? Sorry I know it's hard to grasp but it's basically what my science teacher went through with us today as a final thing to look over as it was something we were all having problems with but I understand bonding a lot better now, once you kind of come to terms with it and just accept that that's what happens and don't really look into it its not as daunting as it sounds haha

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      And no problem @sarah

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      yeah its a bit confusing but ill soon get the hang of it! so how come the positive and negative signs don't stay with the NaCl formula ?

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      To be honest I dont know actually :( @sarah2014

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      ok don't worry about it!! do you know the covalent example?

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      In NaCl there is no charge as the + cancels the -. Therefore, no signs!!

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      but in maths when theres a + and a - the answer is negative?

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      In maths that refers to integers value. in science this refers to relative electrostatic charge, two totally different things!!

      but to put your mind at ease........+2-2 = 0.......they have cancelled!!!

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      so does it always have to add up to 0? sorry for the questions :)

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      I never learnt any of that crap ^ hahaha. All I learnt was what I posted.... including from my book.

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      In ionic molecules (at jc level!) the positive charges will balance/match/cancel the negative ones.

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      oh ok thanks so much :)

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      :-) You're welcome!

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      Yeah sure, so Covalent Bonds are formed as a result of the sharing of at least two pairs of electrons, in covalent bonding each atom shares the same number of electrons, as they are shared. They are typically non metals. Basically, neither wants to donate electrons as they both need electrons (ie: one element doesn't need one and one element doesn't want to get rid of one) An example of Covalent Bonding is Methane, CH4. Its made up of Carbon and Hydrogen. Carbon has 6 electrons, 2 in the first shell and 4 in the outer, meaning it needs 4 electrons to have a full outer shell. To become stable and have a full outer shell, it needs four more. Since hydrogen has 1 electron, four atoms of hydrogen are bonded with the carbon to form CH4, Carbon + 4 Hydrogens. Now, as they are bonded, they share the electrons - The hydrogens have a full outer most shell as they have 2 in the outer shell, which is all they need as the first shell of any element always contains only 2 electrons, and because the four hydrogens share their single electrons with the carbon, it completes carbons outer shell giving it 8 electrons in total, thus forming the molecule CH4.

      That link goes to a diagram, where that might visualize it for you? The X's represent the electrons the hydrogens allowed the carbon to use to achieve the full outer shell.

      Sorry I havent explained that as short or well as Ionic but hopefully it made it a little clearer to understand? Sorry it took so long too btw.

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      You might be asked to say why do elements / atoms share / give away electrons? Remember this always:

      *So that the other element / atom and itself can have a full outer shell as elements have very high reactivity with a non-full outer shell.

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      thanks so much :)

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