According to the periodic table, which two elements have an atomic mass less than twice their atomic number?

Jul 17, 2017

Hydrogen and oxygen

Explanation:

According to the periodic table:

• Hydrogen

$2 \times \text{atomic number} = 2$

$\text{atomic mass} = 1.008$ $\text{amu}$

• Oxygen

$2 \times \text{atomic number} = 16$

$\text{atomic mass} = 15.999$ $\text{amu}$