Finding Valence (1 Viewer)

[music dr]

I have my yearly science exam on tuesday and my teacher forgot to tell us how to find valence, and we need to know for finding chemical formulas. we wrote down how to find the formula, but not the valence.

I have been online and everything and i can't find anything that teaches you how to do it. Please help...

 

[music dr]

Hello? Anyone?

 

[music dr]

Hello? Anyone? i also have another question:

with radicals, is the valency always 1?

 

[Tommy_Lamp]

If your talking about a compound, for example Fe(OH)2, then you cross match. i.e. you take the bottom number of the OH (2), thats the valence of Fe, and then the botom number of Fe (1), thats the valence of OH

if you to read directly of the periodic table, you cant find the valence of transition metals. but the pattern is as follows: Group 1 = +1, 2 = +2, 3 = +3, 4 = +/- 4, 5 = -3, 6 = -2, 7 = -1

hope that helps

 

[Paroissien]

Hello? Anyone? i also have another question:

with radicals, is the valency always 1?

Nope.
A bit of a useless post, but I couldn't resist

 

[music dr]

thanks, its better than nothing

 

[TripleJ]

You can use your periodic table - but its best to memorise them as their are exceptions and complex ions etc.

 

[Paroissien]

Just remember:
Carbonate (CO3) is 2-
Sulfate (SO4) is 2-
Phosphate (PO4) is 3-
Hydroxide (OH) is 1-
Ammonium (NH4) is 1+
Nitrate (NO3) is 1-
And the rest can easily be worked out using the periodic table.
Sorry for the late reply, and seeing as though its Tuesday, this might be useless, but here it is anyway.

 

[smallcattle]

Just remember:
Carbonate (CO3) is 2-
Sulfate (SO4) is 2-
Phosphate (PO4) is 3-
Hydroxide (OH) is 1-
Ammonium (NH4) is 1+
Nitrate (NO3) is 1-
And the rest can easily be worked out using the periodic table.
Sorry for the late reply, and seeing as though its Tuesday, this might be useless, but here it is anyway.

is there any way you can work out the above valences??

 

[Paroissien]

The only way I know how is to draw the Lewis dot diagrams, therefore it is much easier to just remember them

 

[smallcattle]

If your talking about a compound, for example Fe(OH)2, then you cross match. i.e. you take the bottom number of the OH (2), thats the valence of Fe, and then the botom number of Fe (1), thats the valence of OH

if you to read directly of the periodic table, you cant find the valence of transition metals. but the pattern is as follows: Group 1 = +1, 2 = +2, 3 = +3, 4 = +/- 4, 5 = -3, 6 = -2, 7 = -1

hope that helps

so how do you determine the valence for tranition metals say.. silver nitrate??

i know silver is 1+ because it is AgNO3, but is there any method to calculate it??

 

[smallcattle]

The only way I know how is to draw the Lewis dot diagrams, therefore it is much easier to just remember them

umm how do you find out the valence by drawing dot diagrams.. will it work for transition metals??

 

[Paroissien]

You just have to know how many electrons are in the out shell, so you would have to already know that for the transition metals.
It's a crap way to do it though. Just memorise.

 

[Paroissien]

so how do you determine the valence for tranition metals say.. silver nitrate??

i know silver is 1+ because it is AgNO3, but is there any method to calculate it??

No pattern that I know of. You just have to know these

 

[Xayma]

Its to do with the electron sub shells it is covered in the option "Chemistry of Art" but even then transition metals may have multiple valiencies eg Iron ions can exist as Fe²⁺ or Fe³⁺

 

[nit]

Yep, one of the characteristics of transition metals is that they have a number of valences. The +2 state is a safe bet given that the 4s electrons are generally lost. Apart from this, it is best to memorise the valences for the transition metals. There are patterns associated with what type of transition metals you're dealing with. Silver has an electron config of 3d10 4s1, and hence the +1 oxidation state is favourable for it. The same applies for copper and gold. You need to know the electron configurations and make educated guesses.