Counting Atoms

Front

What is the formula to determine the number of atoms of an element in a compound?

Back

Count the coefficient (if present) and multiply it by the subscript of the element in the chemical formula.

Front

In the compound Na₂CO₃, how many sodium (Na) atoms are present?

Back

2

Front

What does the subscript in a chemical formula represent?

Back

The number of atoms of the element in one molecule of the compound.

Front

In the compound (NH₄)₂CrO₄, how many hydrogen (H) atoms are there?

Back

8 (because there are 4 H atoms in NH₄ and the coefficient is 2).

Front

How many different elements are in the compound C₂H₈O?

Back

3 (Carbon, Hydrogen, and Oxygen).

Front

What is the total number of chlorine (Cl) atoms in 6NaCl?

Back

6 (one Cl atom per NaCl unit).

Front

How many magnesium (Mg) atoms are in the compound MgCl₂?

Back

1 (there is one Mg atom per formula unit).

Front

If a compound has the formula C₃H₈, how many carbon (C) atoms are there?

Back

3

Front

What is the significance of the coefficient in a chemical formula?

Back

It indicates how many molecules or formula units of the compound are present.

Front

In the compound 2H₂O, how many oxygen (O) atoms are there?

Back

2 (because there is 1 O atom in each H₂O and the coefficient is 2).