Counting Atoms, Elements, and Molecules
Coefficient
The Big number in front that tells how many molecules there are.
Compound
Two or more atoms of different elements that are chemically combined.
Chemical Formula
Chemical symbols and numbers that show the number of atoms for each element.
Reactants
Elements/compounds at the beginning of the experiment that react together. Found on Left side of arrow.
Products
Elements/compounds that were produced by the experiment. Found on right side of arrow.
8
Number of H in (NH₄)₂CrO₄
9
Number of H in (NH₄)₂Cr₂H
18
Number of O in 6Na₂CO₃
21
Number of O in Al₂(Cr₂O₇)₃
12
Number of O's in Al₂(SO₄)₃
2
Number of Oxygen atoms in 2NaOH
4
Number of atoms of Hydrogen 2CHOH
3
Number of elements in 2NaOH
7
Number of molecules in the compound 7Na₂CO₃
1
Number of molecules in the compound SO₂
5
Number of molecules of 5NaCl
10
Number total atoms in 2NaCO₃
15
Number total atoms in H₄N₂Cr₂O₇
Element
Pure substance that cannot be broken down into anything simpler. One capital letter.
Law of Conservation of Mass
Reactants = Products, What goes into the reaction must come out. Left side = Right side
Subscript
The small number that is below and behind the element that tells the number of atoms.
Molecule
Two or more atoms chemically combined.
6
Total of atoms in 3CaCl
