Science Help Please!!!?

Question

Element Q is a metal with two valance electrons and element X is a non-metal with 5 valence electrons.

a)what ions would you expect Q and X to form?

b)What is the formula of the ionic compound they form?

Please help!!!!
Thnx thnx thnx in advance!!!!!

Answer 1

a) Q 2+ and X 5-

b) Q5X2
(Q's 5 atoms give up 5 x 2 = 10 electrons. X's 2 atoms acquire 2 x 5 = 10 electrons. So the charges balance.

Answer 2

Okay, so if Q is a metal with 2 valence electrons, that means it will either lose 2 electrons or else gain 6 electrons in order to become stable (you can consider 0 or 8 to be the "magic numbers" of a stable valence shell).

Since X has 5 electrons, it will either lose 5 or gain 3 to become stable (again, 0 or 8 means stable).

This answers part a). If Q were to lose it's 2 electrons (which would be the easiest thing to do...easier to lose 2 than gain 6!), then it would lose the 2 negative charges those electrons bring to the atom. This would make Q a +2 ion. Same for X, gaining 3 is easier than losing 5, and that would add 3 negative charges, so you would expect X to be a -3 ion.

Having established the answer for part a), part b) can be deduced by balancing the charge of an ionic compound.
Start by considering the compound

QX

We know that Q is a +2 ion and X is a -3 ion, so this element has an overall charge of -1. For the compound to be stable, the charges must balance. If we add another Q atom, making the compound

Q2X

then we add an additional +2, leaving the overall charge of the compound at +1. Still not neutral.

Adding another X gives us

Q2X2

with an overall charge of -2.

Now, adding another Q, gives us the compound

Q3X2

This compound contains three +2 charges and two -3 charges, leaving the overall compound electrically neutral. This is the compound we expect to form.