## charges and roman numerals

$FC=V-(L+\frac{S}{2})$

D-nice1D
Posts: 19
Joined: Fri Sep 28, 2018 12:21 am

### charges and roman numerals

On the basis of the expected charges on the monatomic
ions, give the chemical formula of each of the following
compounds: (a) magnesium arsenide; (b) indium(III) sulfide;
(c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III)
fluoride

Can someone explain the roles of the roman numerals?

Posts: 36
Joined: Mon Jun 17, 2019 7:23 am

### Re: charges and roman numerals

I think the roman numerals help to tell us how many electrons the molecule has lost or gained. Especially since In is in group 13 it is hard to tell if it has lost 3 electrons or gained more to achieve an octet, so the roman numeral (III) tells us that it is In3+. Also, it tells us Bi is 3+, or has lost 3 electrons.

David Zhang 1B
Posts: 48
Joined: Mon Jun 17, 2019 7:23 am

### Re: charges and roman numerals

The numerals indicate the charge of the atom in the molecule since transition metals can often have several ionic forms. For indium, the 3 indicates In 3+.

Chris Charton 1B
Posts: 69
Joined: Mon Jun 17, 2019 7:23 am

### Re: charges and roman numerals

The Roman Numeral indicates the Oxidation State.

rachel liu 3k
Posts: 56
Joined: Sat Aug 17, 2019 12:16 am

### Re: charges and roman numerals

D-nice1D wrote:On the basis of the expected charges on the monatomic
ions, give the chemical formula of each of the following
compounds: (a) magnesium arsenide; (b) indium(III) sulfide;
(c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III)
fluoride

Can someone explain the roles of the roman numerals?

The roman numeral represents the charge on the ion. The ions with those numbers have more than one oxidation state, and the state cannot usually be gleaned from context or the periodic table, so it is given. Indium (III) would be In 3+ for example.

Nathan Nakaguchi 1G
Posts: 102
Joined: Wed Sep 18, 2019 12:22 am
Been upvoted: 1 time

### Re: charges and roman numerals

Roman numerals next to atoms/metals just indicate the specific charge it has since metals can have a variety of different charges for the same thing. So this one the (III) indicates a +3 charge