Question

All the rules of construction chemical formula

Answer 1

HEY BUDY.....

Rule 1: CRISS-CROSS rule

1. write the correct symbols of the elements and radicals

2. Above each symbol, write the correct valence or oxidation numbers.

Ex. Al+3 O-2

3. To obtain the proper subscript, criss-cross the valence or oxidation

number,and drop the algebraic sign.

Ex. Al+3O-2 became Al2O3

Rule 2: When the subscript is number 1, subscript is not written.

Ex. Sodium Chloride- Na+1 Cl+1 --- NaCl

Rule 3: When the oxidation # of both elements are numerically equal but grater than 1, the subscript are not also written.

Ex. Calcium Oxide~ Ca+2O-2 ----- CaO

Rule 4: All radicals tke more than once( the subscript is 2 or more) must be

enclosed in Pahrentheses().

Ex. Ammonium Sulfate NH4+1 SO4-2-----(NH4)2 SO4

RULE 4: All subscripts must be reduced to lowest term (except for molecular or

covalent copound).

Ex. Tin (IV) Chloride ~ Sn+4Cl-1------ SnO2

*ANOTHER RULE*

Write the symbol for the atom or polyatomic ion with the positive oxidation number first.

Ex. Al+3

Follow this with the symbol of the atom or polyatomic ion with a negative oxidation number.

Ex. I-1

Use subscripts to make the sum of the oxidation numbers equal to the charge of ions.

Ex. Al+3 and I-1

We write AlI3

When a subscript is used with an ion containing two or more elements, the ion must be enclosed in parentheses () before writing the subscript.

Ex. Mg+2 and NO3-1

is written as Mg (NO)

HOPES IT IS '' OK ''

Answer 2

First of all you have to know the symbol of the elements.

For example: Sodium=Na, Potassium=K, Iron=Fe, etc.

Second, you have to know the valency of the element.

For example: Sodium=1, Magnesium=2, etc.

Next, you should cross multiply the elements and the valencies as shown below

                                       

                     Hydrogen Oxide(Water)