Counting Atoms in Chemical Formulas

Front

What is the formula for calculating the number of atoms in a chemical formula?

Back

Count the number of each type of atom present in the formula, considering subscripts and parentheses.

Front

How many total atoms are in the formula C₃H₅(NO₃)₃?

Back

17 atoms (C=3, H=5, N=3, O=9).

Front

What does a subscript in a chemical formula indicate?

Back

The number of atoms of the element in the molecule.

Front

If there is no subscript after an element symbol, how many atoms of that element are present?

Back

1 atom.

Front

How many hydrogen atoms are in the compound H₂O?

Back

2 hydrogen atoms.

Front

In the formula H₂SO₄, how many sulfur atoms are present?

Back

1 sulfur atom.

Front

What is the total number of oxygen atoms in H₂SO₄?

Back

4 oxygen atoms.

Front

How do you determine the number of atoms in a compound with parentheses?

Back

Multiply the subscript outside the parentheses by the subscripts of each element inside.

Front

What is the total number of atoms in 4H₂O?

Back

8 hydrogen atoms (4 x 2 = 8) and 4 oxygen atoms, totaling 12 atoms.

Front

In the formula C₃H₅(NO₃)₃, how many nitrogen atoms are there?

Back

3 nitrogen atoms.