iPad *90% 11:31 AM webassign.net For each of the following ions, indicate the to
ID: 570823 • Letter: I
Question
iPad *90% 11:31 AM webassign.net For each of the following ions, indicate the total number of protons and electrons in the ion. For the positive ions in the list, predict the formula of the simplest compound formed between each positive ion and the oxide ion. For the negative ions in the list, predict the formula of the simplest compound formed between each negative ion and the aluminum ion (a) N3- protons electrons 101 compound chemPad Help Greek (b) Sc3+ protons electrons 18 21 compound chemPad Help GreekExplanation / Answer
The number of protons is nothing but the atomic number of the element. The number of electrons is given by -
no. of e = atomic number + charge on atom (if the charge is negative)
no. of e = atomic number - charge on atome (when the charge is positive)
Prediction of formula for simplest compounds
To form a neutral compound, the positive and negative charges should be equal so that the net charge of the compound is zero. If the cation is Cm+ and anion is An-, then generally the simplest compound formed is CnAm. When n and m are same, the compound is just CA.
Using these rules, we can predict the number of protons, electrons and simplest compound in each case. I will show detailed explaination for a cation and an anion. It'll be obvious for you to predict others.
a) N3-
number of protons = atomic number of nitrogen = 7
number of electrons = atomic no. of N + charge = 7 + 3 = 10
(you add the charge because it's negative)
Now, the simplest compound is -
Since it's negative ion, we have to predict the compound with Aluminium which has an oxidation number (or charge) of +3. Therefore, using the above rules, the compound is Al3N3. Since both charges are same here, one cation (Al3+) will react with one anion (N3-) to form AlN. Always remember to write the cation first. It's the convention!
When you're predicting the formula of compound, one way to be sure is to calculate the net charge of the compound by adding all the positive and negative charges. This should add up to zero.
b) Sc3+
no. of protons = atomic no. of Sc = 21
no. of electrons = atomic no. - charge = 21 - 3 = 18 (because the charge is positive here)
Simplest compound -
Sc3+ is a positive ion, so we have to predict its compound with oxide ion which has an oxidation number (or charge) of -2. Therefore, using the above rules, the compound is Sc2O3
c) Cs+
no. of protons = 55
electrons = 54
Simplest compound - Cs2O
d) Mg2+
no. of protons = 12
no. of electrons = 10
simplest compound - Mg2O2 or MgO
e) P3-
no. of protons = 15
no. of electrons = 18
simplest compound - Al3P3 or AlP
f) S2-
no. of protons = 16
no. of elctrons = 18
simplest compound = Al2S3
g) Ti4+
no. of protons = 22
no. of elctrons = 18
simplest compound = TiO2
h) F-
no. of protons = 9
no. of elctrons = 10
simplest compound = AlF3
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