HydrogenHydrogen has 1 electron, on the first shell. Its nucleus is 1 proton; the most common isotope has no neutron.
HeliumHelium has 2 electrons, both on the first shell. Its nucleus holds 2 protons and, in its most common isotope, 2 neutrons.
LithiumLithium has 3 electrons: 2, 1. Its nucleus holds 3 protons and, in its most common isotope, 4 neutrons.
BerylliumBeryllium has 4 electrons: 2, 2. Its nucleus holds 4 protons and, in its most common isotope, 5 neutrons.
BoronBoron has 5 electrons: 2, 3. Its nucleus holds 5 protons and, in its most common isotope, 6 neutrons.
CarbonCarbon has 6 electrons: 2, 4. Its nucleus holds 6 protons and, in its most common isotope, 6 neutrons.
NitrogenNitrogen has 7 electrons: 2, 5. Its nucleus holds 7 protons and, in its most common isotope, 7 neutrons.
OxygenOxygen has 8 electrons: 2, 6. Its nucleus holds 8 protons and, in its most common isotope, 8 neutrons.
FluorineFluorine has 9 electrons: 2, 7. Its nucleus holds 9 protons and, in its most common isotope, 10 neutrons.
NeonNeon has 10 electrons: 2, 8. Its nucleus holds 10 protons and, in its most common isotope, 10 neutrons.
Name the atom: 11 to 20 10
SodiumSodium has 11 electrons: 2, 8, 1. Its nucleus holds 11 protons and, in its most common isotope, 12 neutrons.
MagnesiumMagnesium has 12 electrons: 2, 8, 2. Its nucleus holds 12 protons and, in its most common isotope, 12 neutrons.
AluminumAluminum has 13 electrons: 2, 8, 3. Its nucleus holds 13 protons and, in its most common isotope, 14 neutrons.
SiliconSilicon has 14 electrons: 2, 8, 4. Its nucleus holds 14 protons and, in its most common isotope, 14 neutrons.
PhosphorusPhosphorus has 15 electrons: 2, 8, 5. Its nucleus holds 15 protons and, in its most common isotope, 16 neutrons.
SulfurSulfur has 16 electrons: 2, 8, 6. Its nucleus holds 16 protons and, in its most common isotope, 16 neutrons.
ChlorineChlorine has 17 electrons: 2, 8, 7. Its nucleus holds 17 protons and, in its most common isotope, 18 neutrons.
ArgonArgon has 18 electrons: 2, 8, 8. Its nucleus holds 18 protons and, in its most common isotope, 22 neutrons.
PotassiumPotassium has 19 electrons: 2, 8, 8, 1. Its nucleus holds 19 protons and, in its most common isotope, 20 neutrons.
CalciumCalcium has 20 electrons: 2, 8, 8, 2. Its nucleus holds 20 protons and, in its most common isotope, 20 neutrons.
Fill the shells 10
2, 1Lithium has 3 electrons. They fill the shells from the inside out: 2, 1.
2, 4Carbon has 6 electrons. They fill the shells from the inside out: 2, 4.
2, 6Oxygen has 8 electrons. They fill the shells from the inside out: 2, 6.
2, 8Neon has 10 electrons. They fill the shells from the inside out: 2, 8.
2, 8, 1Sodium has 11 electrons. They fill the shells from the inside out: 2, 8 and 1.
2, 8, 3Aluminum has 13 electrons. They fill the shells from the inside out: 2, 8 and 3.
2, 8, 5Phosphorus has 15 electrons. They fill the shells from the inside out: 2, 8 and 5.
2, 8, 7Chlorine has 17 electrons. They fill the shells from the inside out: 2, 8 and 7.
2, 8, 8, 1Potassium has 19 electrons. They fill the shells from the inside out: 2, 8, 8 and 1.
2, 8, 8, 2Calcium has 20 electrons. They fill the shells from the inside out: 2, 8, 8 and 2.
Outer shell to dots 8
1 valence electronThe outer shell holds 1 electron. It becomes one dot around the symbol box.
2 valence electronsThe outer shell holds 2 electrons. Each becomes one dot around the symbol box.
3 valence electronsThe outer shell holds 3 electrons. Each becomes one dot around the symbol box.
4 valence electronsThe outer shell holds 4 electrons. Each becomes one dot around the symbol box.
5 valence electronsThe outer shell holds 5 electrons. Each becomes one dot around the symbol box.
6 valence electronsThe outer shell holds 6 electrons. Each becomes one dot around the symbol box.
7 valence electronsThe outer shell holds 7 electrons. Each becomes one dot around the symbol box.
8 valence electronsThe outer shell holds 8 electrons. Each becomes one dot around the symbol box.
How this list was compiled: Electrons per shell for elements 1 to 20 checked on 2026-10-03 in two sources that agree for all twenty: Wikipedia, Electron shell (list of elements with electrons per shell), and Purdue University, General Chemistry Topic Review, https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/quantum.html (electron configurations, added up shell by shell). The most common isotope of each element, for the neutron counts, in two sources that agree for all twenty: NIST, Atomic Weights and Isotopic Compositions, https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=&ascii=ascii2&isotype=some , and the Commission on Isotopic Abundances and Atomic Weights, https://www.ciaaw.org/isotopic-abundances.htm . Valence electrons as the electrons of the outer shell: Wikipedia, Valence electron, and Purdue, Lewis Structures. The name Bohr-Rutherford diagram: three school textbooks read through archive.org full-text search, and Wikipedia, Bohr model. Licence: own work
The drawing: Drawn for this site on 2026-10-03 by a script from the table of atoms in this file: own work. Nothing traced. Licence: own work
How it works
This Bohr diagram worksheet, first 20 elements in order, shows hydrogen to calcium with their electrons on shells. Name each atom, fill the shells of ten more, and count the valence electrons of eight. Print it, or answer on screen.
Read the full guide
Read a Bohr diagram
The disc in the middle is the nucleus and each ring is a shell. Count the electrons ring by ring from the inside. In these atoms the first shell holds up to 2, the second up to 8 and the third up to 8; potassium and calcium start a fourth. The total is the atomic number, which names the element. The atoms run in order, so it doubles as a periodic table Bohr diagram worksheet.
Fill the shells, then the dots
On paper, draw the electrons on the ten empty atoms; the number under each is its atomic number. The last block is a small Bohr and Lewis dot diagrams worksheet: each outer electron becomes one dot beside the symbol box.
For a Bohr model and Lewis dot diagram worksheet, have the class write each element's symbol in its box.
The answer key lists every name, arrangement and valence count by number.
Questions and answers
Is there a Bohr diagram worksheet PDF?
Yes. Press Print this worksheet and choose Save as PDF in the print window. Print the answer key gives the same sheet with every answer listed under it.
How do you draw a Bohr diagram?
Find the atomic number: an atom has that many electrons. Draw the nucleus, then rings around it. For elements 1 to 20, put up to 2 electrons on the first ring, up to 8 on the second and third, then the rest on the fourth.
Is a Bohr-Rutherford diagram worksheet the same thing?
Yes. A Bohr-Rutherford diagram is the same drawing under a fuller name: the nucleus in the middle and all of the atom's electrons on their shells. Some textbooks also write the numbers of protons and neutrons inside the nucleus.
Is this a Bohr diagram and Lewis structure worksheet?
In part. The last block turns the outer shell of eight atoms into dots, the way a Lewis dot symbol shows valence electrons. Lewis structures of whole molecules, with their bonds, are not on this sheet.