Question

How would i find the chemical formula of something such as
Magnesium (Mg) & Chlorine (Cl)

Answer 1

Welcome to OpenStudy. You can look it up, or you can figure it out. You will need to know what ions they form.

Answer 2

You can just look at the periodic table and see what ions they form.

Answer 3

As elements, they can be found as metallic magnesium Mg and molecular chlorine \(Cl_2\)

Answer 4

Have a look at a periodic table, such as https://en.wikipedia.org/wiki/Periodic_table_(large_version)

Look at Mg — it's in group 2, an alkali earth metal. alkali earth metals usually have a valence number of 2, so they'll want to bond with an atom or atom(s) which have a valence number of -2. Cl is in group 17, the halogens, and they have a valence number of -1. So, you'll have two atoms of Cl (-1 each) and 1 atom of Mg (+2 each): MgCl2

Sodium chloride (aka plain old table salt) is made up of Na (an alkali metal, usually a valence number of 1) and Cl, which we already know is valence -1. Therefore, it's a one-to-one pairing, and the formula for table salt is NaCl. Some people with hypertension need to control their sodium intake, and use potassium chloride instead of sodium chloride. A quick glance shows that potassium (K) is in the same group as sodium, and so it should be no surprise that potassium chloride has the formula KCl.