Atomic composition and structure. Isotopes.

The title of the Project: Atomic composition and structure

This virtual laboratory is intended for use in chemistry classes on the following topics:

  • 7th grade. Chapter III. “Atoms. Molecules. Substances.”
  • 7th grade. Chapter VI. “Periodic table of chemical elements”

Purpose of the virtual laboratory work:

  • To identify the subatomic particles (protons, neutrons, electrons) and understand their location and charges.
  • To manipulate virtual atoms: Build atoms by placing protons, neutrons, and electrons in their respective locations.
  • To observe the impact of changing atomic structure: Understand how different combinations of protons, neutrons, and electrons affect the element and its properties.
  • To connect atomic structure to the periodic table: Recognize the relationship between the number of protons and an element’s position on the periodic table.

Practical part

Characteristics of atomic particles

Table 1

ParticlesMass numberCharge numberNote
proton+1The number of protons is equal to the ordinal number of the element
neutron0The number of neutrons can be found by the following formula:N=А -Z , А -atomic mass number, Z – number of protons
electron-1The number of electrons is equal to the ordinal number of the element

Virtual experiment No.1 : Atomic structure

  1. Start the simulation. You will be testing two different screens and play games in the end to check your ability to use what you have learned. Let’s take a look at the Atom screen first.

  1. The screen shows an empty model of the atom and the particles it consists of. By holding down the left mouse button, you can drag them into the atomic model.

  1. It is known that in the construction of an atom, each subatomic particle has its place. For example, a proton and a neutron form the nucleus of an atom in the center. Electrons rotate around the nucleus in orbitals. Such a model of the atom is called The Bohr model.

  1. Place a proton particle in the center of the atom. The element name will immediately appear on the screen. In the periodic table on the right,you can see the symbol of the formed element. The lower section shows the charge and mass number of the element. In addition, by checking the boxes in the “Show” section, you can show or hide the name of the element, whether it is a neutral atom or ion, stable or unstable.

  1. In this case, we see that our formed element is a hydrogen ion. Add an electron to turn it into a neutral atom. As a result, the charge of the atom changes from positive to neutral. And the mass number remains unchanged. Why?

  1. You can represent electrons as orbitals or an electron cloud.

  1. Add more protons. Pay attention to the periodic table. What did you notice? The number of protons determines the position of an element in the periodic table, so by adding protons, you move along the periodic table.

  1. Press the Reset button and restart the simulation. Check the box in the Stable/Unstable section.

  1. Now build a Helium atom. The Helium atom ranks second in the periodic table. Therefore, it contains 2 protons and 2 electrons. Place the given number of particles in the atom. What did you notice? Why is the helium atom unstable in this state?
  1. To make an atom stable, add neutrons to it. To do this, determine the number of neutrons according to the formula given in Table 1. In the given periodic table, the mass number of the element is not specified, so use the basic periodic table of Mendeleev.

Virtual experiment No.2 : A chemical symbol

  1. Switch to the “Symbol” mode. Here, the mass number and charge of the atom are indicated as parts of the element symbol. Using this section, you can understand what the numbers in the element symbol represented in the periodic table mean.

  1. Make up the symbols of Hydrogen and Helium. To do this, repeat the steps from the first experiment. What influences the change in the mass number and charge of an atom?

  1. Now switch to the ”Game” mode to consolidate your knowledge. There are 4 different games in this section. Each game consists of 5 stages. A clock image is displayed in the lower left corner of the screen. By clicking on it, you can compete with your partner for speed.

  1. The first game is called “Find the element!”. You must identify the symbol of the element hiding in the periodic table according to a given atomic model.

  1. In the second game, you will determine the mass number and charge of the atom.

  1. In the third, you must add the missing information to the element symbol.

  1. In the fourth game, you need to identify an element by creating its symbol.


Through this virtual laboratory work, students have learned that atoms, the building blocks of all matter, are composed of protons, neutrons, and electrons. By manipulating these virtual atoms, they observed how altering their structure impacts the element and its properties. Importantly, they discovered the link between the number of protons and an element’s location on the periodic table.