In Chemistry how do you know the total charge of cations and anions of elements?

Question

I have a chart but some of the elements don't show the total charge or 2 possible charges. For example, my chart shows Mg has a 2+ charge. But Fe could be 2+ or 3+? How do I determine which one? Also I can't find a charge for group 4A or 5A does that mean there is no charge and the compound would be covalent? Thanks for any help!

Answer 1

dun panic with Fe.

The paper usually provide enough information. They may clearly state that Iron(II) Sulphate or Copper(III) nitrate ,etc. In most situation iron2+, Cu2+ is commonly use.





However, sometime it may not tells you which Fe ion is used exactly. say balance an equation, if u can not got the answer by using Fe2 then u can try Fe3

Answer 2

Mg has a +2 charge because it is an alkaline earth metal. But Fe is a transition metal. Transition metals can have more than one charge. To determine which one to use, you will have to have a compound. For example if your compound is FeO, you know to use the Fe with a +2 charge because O has a -2 charge and when you "criss-cross" the charges, It would come out looking like this:

FeO = Fe2O2 because it's the same ratio (2:2 = 1:1)! Then when you criss cross, O would have a -2 charge, and Fe would have a +2 charge!

Answer 3

Cation And Anion Chart

Answer 4

the oxidation number depends on electron configuration. Mg can release 2 electrons from 3s2 orbital.

Then, elements in transition group (B) have their last electron in orbital d. orbital d is quite unstable, so that explains why some elements of this group have two or more oxidation number. you determine it by...well, by seeing the problem. sometimes you use +2, or +3. if you're doing a test, they'll tell you the IUPAC name of the compound to give you a clue to know 'is it +2? +3?'

if it's for labs, i usually remember the common compound of the elements. like FeCl3, Fe2O3, FeI2...



although the elements of group IVA and VA do have oxidation number, but the elements in group IVA and VA have no charge indeed. they only have charge when they form some compounds with other elements.example: phospate ion (PO4 -3), carbonate ion (CO3 -2), sulphate ion (SO4 -2). yes, you're right, single elements from those groups form covalent bonds.

Answer 5

For elements which have more than one charge eg:Fe or cu ,u cannot know their charge as alone element, but when they are in compound, then you can by finding out each element charge and exchange their charge.

eg: in Feo (as u should memories the charges for elements with single charge such as o ,u should know it has 2_ charge) because o has a charge 2 therefore iron in here must be 2 as well .You should just learn to exchange the charges. it means to give the o charge to F and f to O. another eg is: Fe2o3 ,in here iron charge is 3.

In sum for each element the number of their groupe represents their charge.eg: group 1 is1+,group 2 and 3 are2+,3+(AL),then anions which are group4,5,6,7 have charges4-,5-,6-,and7-.the group8 elements do not react and therefore they don't have any charge.



hope my information becomes helpful.

Answer 6

Only the columns with a roman numeral I, II, III, V, VI, VII, and VIII followed by "A" are somewhat predictable. Take Group IIA, all those elements form +2 ions. Group VA, all those elements tend to be -3. etc. Group IVA is a mixed bag where you can have +4 or +2.

The columns with "B" designations (the transition metals) are unpredictable; you just have to learn the charges on individual elements.

Answer 7

K is located below Na in the same group, That group loses elecrons easily becomeing cations. So K would be K+ while PO4 would have a negative charge. Just like that, find elements in the same group they all behave the same way.