In order to recognize the number of protons, neutrons, and also electrons, we need to look in ~ the regular table of elements. Below is a partial periodic table. Click below to view a finish periodic table (scroll under to the 2nd page).

You are watching: To find the number of neutrons in an atom, you would subtract

*

Let"s look very closely at the information uncovered on the table for the aspect beryllium. Different periodic tables could have a contempt different way of displaying the information around the elements, however all routine tables have the following information. Click on each item of info to learn more about what it speak us.


So, if we need to determine the number of protons, we merely look in ~ the element"s atom number.

How many protons go beryllium have?

Interactive popup. Help may be required.

Check your Answer

4

In a stable atom, the number of protons and also electrons are constantly equal. For this reason to determine the number of electrons in one atom, you need to understand the variety of protons.

How many electrons walk beryllium have?

Interactive popup. Aid may it is in required.

Check her Answer

4

The atom mass of one atom is the number of protons and neutrons uncovered in the cell core of one atom. The atom mass is usually a decimal number. Once determining the number of neutrons, round the atomic mass come the nearest entirety number. Because that example, the atomic mass the beryllium is 9.0112 therefore you would certainly round the to 9.

To calculate the variety of neutrons, take the atom mass, i beg your pardon is the variety of protons and also neutrons, and also subtract the atomic number, which is the number of protons in one atom. The result is the number of neutrons.


*

How countless neutrons does an atom the beryllium have?

Interactive popup. Assistance may be required.

Check her Answer

5

Let"s shot another example. Listed below is the periodic table entry for sodium. Recognize the variety of protons, neutrons, and also electrons.

See more: How Do You Say " What Does Cual Es Tu Numero De Telefono Mean


Given a drawing of an aspect as watched below, would certainly you be able to identify the element and the variety of protons, neutrons, and also electrons?


*

At an initial glance you might think, "No, i cannot identify the aspect because I execute not know if the red or green circles room the proton or neutrons, and also they are overlapping so i cannot counting them."

If friend think carefully, girlfriend can number it out. That is straightforward to identify and also count the number of electrons. There are 8 electron total. If there room 8 electrons, climate there room 8 protons. Eight protons means the atom number is 8. You deserve to then look on the routine table to determine the element.