A free printable Lewis structures worksheet for Grade 11 chemistry.
This free lewis structure worksheet builds the skill step by step: count valence electrons, total them for molecules and ions, then draw eight Lewis structures, from simple H₂O to CO₂'s double bonds, the triple bonds in HCN and N₂, and the NH₄⁺ ion.
Students then count bonding and lone pairs, draw Lewis diagrams for ionic compounds, and fix two common mistakes. The answer key shows every structure drawn out, and each one was checked by computer for the right number of electrons and a full octet on every atom.
| Part | Skill practised | Marks |
|---|---|---|
| A | Valence electrons of elements | 3 |
| B | Total valence electrons in molecules and ions | 3 |
| C | Draw eight Lewis structures | 8 |
| D | Bonding pairs and lone pairs | 2 |
| E | Lewis diagrams for ionic compounds | 2 |
| F | Spot the mistake | 2 |
It supports the Ontario Grade 11 chemistry curriculum expectations in the Matter, Chemical Trends and Chemical Bonding unit.
Every structure on this Lewis structure worksheet follows these five steps. For more background, see Lewis structures on Wikipedia.
Here is how to work through question 17 on the Lewis structure worksheet.
A final check: 2 electrons in H–C + 6 in C≡N + 2 in the lone pair = 10, which matches the count from step 1. Always finish with this check, because it catches most mistakes before they cost marks.
For main-group elements, the number of valence electrons matches the last digit of the group number: carbon has 4, nitrogen 5, oxygen 6 and chlorine 7. For an ion, add electrons for a negative charge and subtract for a positive one.
| Species | Total valence electrons |
|---|---|
| H₂O | 8 |
| CO₂ | 16 |
| NH₄⁺ | 8 |
| SO₄²⁻ | 32 |
| CH₃OH | 14 |
| NO₃⁻ | 24 |
Valence electrons come straight from electron configurations, covered in the electron configuration worksheet.
CO₂ has 16 valence electrons. With single bonds, carbon would only have 4 electrons, so each oxygen shares a second pair, giving O=C=O. N₂ needs a triple bond for both atoms to reach 8. The ammonium ion is drawn in square brackets with its charge outside. Students draw these and five more in Part C of the Lewis structure worksheet.
In ionic compounds, electrons are transferred, not shared. The metal becomes a positive ion with no dots shown, and the non-metal becomes a negative ion with a full octet in brackets. The ionic or covalent worksheet helps students decide which kind of bonding applies.
These questions match the Lewis structure worksheet PDF, which has tables and drawing boxes for every question.
Questions 1–6: give the number of valence electrons for C, N, O, Cl, Mg, Ne.
Questions 7–12: find the total valence electrons in H₂O, CO₂, NH₄⁺, SO₄²⁻, CH₃OH, NO₃⁻.
Questions 13–20: draw Lewis structures for H₂O, NH₃, CH₄, CO₂, HCN, N₂, CH₂O, NH₄⁺.
Questions 21–24: count the bonding pairs and lone pairs on the central atom of H₂O, NH₃, CO₂, N₂.
Questions 25–26: draw Lewis diagrams for NaCl and MgO.
Open each part of the Lewis structure worksheet answers to check your work. The printable key, with every structure drawn, is at the end of the PDF.
Next, predict shapes with the VSEPR worksheet, and review with the Lewis structures, polarity and shapes quiz.
Yes. The worksheet and its answer key are free to download and print as a PDF, with no account needed.
Count the total valence electrons, put the least electronegative atom in the centre, join the atoms with single bonds, complete the outer atoms' octets, and then use lone pairs to make double or triple bonds if the central atom still needs electrons.
Add the valence electrons of every atom, then add one electron for each negative charge or subtract one for each positive charge. NH₄⁺ has 5 + 4 − 1 = 8 valence electrons.
When the electrons run out before every atom has an octet. CO₂ needs two double bonds and N₂ needs a triple bond.
Hydrogen can only hold two electrons, so it forms just one bond and always sits on the outside of a structure.
Ready to start? Download the free Lewis structure worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.