Question

An atom of silicon has a mass number of 28 and an atomic number of 14. How can you determine how many protons and how many neutrons are in this atom?

Answer 1

A silicon atom with a mass number of 28 and an atomic number of 14 has 14 protons, as the atomic number equals the number of protons. To find the number of neutrons, subtract the atomic number from the mass number, resulting in 14 neutrons.

Step-by-step explanation:

To determine the number of protons and neutrons in a silicon atom with a mass number of 28 and an atomic number of 14, we can use the definitions of atomic number and mass number. The atomic number is equal to the number of protons the atom contains, and it is also the number that distinguishes one element from another. Therefore, a silicon atom has 14 protons. To find the number of neutrons, we subtract the atomic number from the mass number, which represents the total number of protons and neutrons in the nucleus. Using this information:

• Number of protons = Atomic number = 14
• Number of neutrons = Mass number - Atomic number = 28 - 14 = 14

Finally, a silicon atom with a mass number of 28 and an atomic number of 14 has 14 protons and 14 neutrons in its nucleus.

Answer 2

The atomic number of an atom is the number of protons in its nucleus.
If the silicon atom has an atomic number of 14, then there are 14 protons
in its nucleus.

The mass number of the atom is the total number of (protons + neutrons)
in its nucleus. If the silicon atom has a mass number of 28, and we know
that 14 of those are protons, then neutrons account for the other (28 - 14)
= 14 neutrons.

You may be wondering about all the electrons whizzing around the nucleus.
That's an excellent question, one that I thought you weren't going to ask.

In a neutral atom, the number of electrons is the same as the number of
protons, so their number is the same as the atomic number.

Regarding the atom's mass, the electrons make just about zero difference ...
one neutron or one proton has the mass of about 1840 electrons, so there's
practically no difference if we ignore the electrons completely.