Chemical formula that compound will be made up of the same elements in the same proportion or ratio. For example, any water molecule is always made up of two hydrogen atoms and one oxygen atom in a 2:1 ratio. If we look at the relative masses of oxygen and hydrogen in a water molecule, we see that 94% of the mass of a water molecule is accounted for by oxygen and the remaining 6% is the mass of hydrogen. This mass proportion will be the same for any water molecule. The alkene called but-2-ene has two isomers, which the chemical formula CHCH=CHCH
Formula for primes Formula for primes In number theory, a formula for primes is a formula generating the prime numbers, exactly and without exception. No such formula which is efficiently computable is known. A number of constraints are known, showing what such a "formula" can and cannot be. A simple formula is By Wilson's theorem, formula_3 is prime if and only if formula_4. Thus, when formula_3 is prime, the first factor in the product becomes one, and the formula produces the prime number formula_3. But when formula_3 is not prime, the first factor becomes zero and the formula produces the prime number 2.