Question

In a chemical equation, numbers often appear in front of a chemical formula. These numbers tell you ________.

1) the atomic number of the element
2) the mass number of the element
3) the number of atoms or molecules involved
4) the valency of the element

Answer 1

In a chemical equation, the numbers in front of chemical formulas are coefficients that correspond to the number of atoms or molecules involved in the reaction, which indicate the mole ratios of the reactants and products.

Step-by-step explanation:

In a chemical equation, the numbers that appear in front of a chemical formula are called coefficients. These coefficients tell you the number of atoms or molecules involved in the reaction. More specifically, they indicate the mole ratio of the reactants and products involved in the chemical reaction. It's important to distinguish these from subscripts, which are part of chemical formulas and indicate the number of atoms of each element within a single molecule or compound.

For example, in the chemical equation 2H₂O → 2H₂ + O₂, the coefficient '2' in front of H₂O indicates there are two molecules of water involved in the reaction. These coefficients are essential for balancing chemical equations, ensuring that the same number of atoms of each element is present on both sides of the equation, in accordance with the law of conservation of mass.