Question 2.4: A number of elements have an equal number of protons and neu...
A number of elements have an equal number of protons and neutrons in
their nuclei. Among these are oxygen, nitrogen and, neon. What are the
atomic numbers of these elements? How many protons and neutrons does
an atom of each have? Write the name and the symbol of each of these
atomic nuclei.
Strategy
Look at the Periodic Table to determine the atomic number of each element.
Mass number is the number of protons plus the number of neutrons.
Atomic numbers for these elements are found in the list of elements on the inside back cover. This table shows that oxygen (O) has atomic number 8, nitrogen (N) has atomic number 7, and neon (Ne) has atomic number 10. This means that oxygen has 8 protons and 8 neutrons. Its name is oxygen-16, and its symbol is _{8}^{16}O. Nitrogen has 7 protons and 7 neutrons, its name is nitrogen-14, and its symbol is _{7}^{14}N. Neon has 10 protons and 10 neutrons, its name is neon-20, and its symbol is _{10}^{20}Ne.