we are working on chemical formulas and we know how to balcane the formula, but not sure where the numbers come from. ex: ferric chloride=FeCl3~where did the 3 come from?
2007-02-11 01:22:36 · 6 answers · asked by Lynn W 1 in Science & Mathematics ➔ Chemistry
Iron has two possible valency of +2 and +3. +2 Compounds are known as ferrous, whilst +3 valency compounds are known as ferric. Chlorine has a valency of -1 (which is common and known as a chloride), or +7 (which is rare). As all compound are neutral charges it makes senses that 3 chloride ions are needs to balance the charge of one ferrous ion. This is +3 comes from.
2007-02-11 01:32:19 · answer #1 · answered by The exclamation mark 6 · 0⤊ 1⤋
The number after is how many atoms a substance has i.e. cl3
means chloride has 3 atoms in this formula combined with Iron.
(Fecl3) Also means that the Iron only has 1 atom (Mono)
Iron=1 atom Chloride=3 atoms. This will always be when the elements give there atoms if you don't see a number means that there is only one in a molecule formula.
2007-02-11 01:37:22 · answer #2 · answered by Vernon T 1 · 0⤊ 0⤋
You should be able to find a "Valency Table" on the internet somewhere. The simple rule is that the valency of the first element is written after the second, and vice versa. Then you cancel down if you can, and then miss out any number 1s.
So from Fe = valency 3 and Cl = valency 1, swapping them over we get Fe1Cl3, and then we miss out the 1 to get FeCl3.
2007-02-11 01:34:34 · answer #3 · answered by Gervald F 7 · 0⤊ 0⤋
In your example, in a molecule of Ferric Chloride, there is one Iron atom and 3 chlorine atoms.
Line in H2O. There are two hydrogen atoms and one oxygen atom.
2007-02-11 01:31:18 · answer #4 · answered by Walking Man 6 · 0⤊ 0⤋
in combining elements, we use the criss-cross method... it means that we cross the charges of 2 elements... Iron is a cation... it is either trivalent or divalent.. (trivalent is an element having either 3 or -3 as the charge.. it depends upon the element if it is cation or anion... and divalent has 2 charges. lyk monovalent, it can either be 2 or -2)... Since u used the word ferric, it refers to the trivalent iron... Cl is monovalent... so, if we cross the 2 elements... the charge of Iron will be transfered to Cl and the charge of Cl will be transfered to Fe...
Therefore, 3 came from the Iron... because 3 is the charge of Iron...
2007-02-11 01:36:29 · answer #5 · answered by Steph_kinse 2 · 0⤊ 0⤋
For the numbers you need to look at the.. uhmm.. (rusty at this).. valence numbers.. Fe has a valence of 3 while Cl has a valence of only 1.. you need 3 of the Cl to fill in the valence of just one Fe...
Look at it this way.. you have 3 empty holes in Fe and you have just one extra eletron in each Cl so in order to fill in all 3 of the empty holes (to make a stable compound) you need 3 Cl atoms.
2007-02-11 01:31:40 · answer #6 · answered by ♥Tom♥ 6 · 0⤊ 0⤋