Question

sodium chloride formula by crisscross method​

Answer 1

NACL.. sodium chloride ..

NA+.. CL-

Answer 2

Explanation:

Criss Cross Method for Predicting Formulas

Ions attract one another to form neutral compounds. We will employ the criss cross method to predict the ration of ions in a compound and therefore predict the chemical formulas.

Let’s look at 2 ions sodium (Na+1) and chlorine (Cl-1). We know that these ions combine in a 1:1 ratio. 1 Na ion for every 1 Cl ion. The compound that results is NaCl (sodium chloride).

Now let’s use the criss cross method. In the criss cross method you take the number for the charge on an ion (ignore the positive and negative) and you make it the other atoms subscript.

Now let’s look at calcium chloride (CaCl2)

Now let’s look at aluminum chloride (AlCl3)

As you can see knowing the charge of the ions makes it extremely simple to predict formulas.

Let’s take a look at sodium oxide.

Let’s take a look at magnesium oxide

In a case like these where you have two ions that have the same number of an oxidation state you want to find the least common multiple of the numbers. Always reduce the compound to its simplest form when dealing with ionic compounds.

Aluminum Oxide

So let’s check if this method has still generated a compound with a net 0 charge. To do this all we need to do is add up all the positive charges and add that to the sum of all the negative charges.

2 Al+3 = (+3) + (+3) = +6

3 O2- = (-2) + (-2) + (-2) = -6

(+6) + (-6) = 0 neutral compound

Therefore the compound’s formula is correct.

What would the formula be for Pb+4 and Ob2- be?

Remember always reduce to the least common multiple.