A student drew this as the dot diagram of aluminum. What is wrong with it? (Picture: The symbol Al with dots around it: a single dot on the top, a single dot on the right.)Answer: One dot is missing. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of boron. What is wrong with it? (Picture: The symbol B with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom.)Answer: Nothing: it is right. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of calcium. What is wrong with it? (Picture: The symbol Ca with dots around it: a single dot on the top.)Answer: One dot is missing. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
Show all 75 questions (72 more)
Atoms: dots around a symbol, continued
A student drew this as the dot diagram of carbon. What is wrong with it? (Picture: The symbol C with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Nothing: it is right. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of chlorine. What is wrong with it? (Picture: The symbol Cl with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a single dot on the left.)Answer: Nothing: it is right. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of fluorine. What is wrong with it? (Picture: The symbol F with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a pair on the left.)Answer: There is one dot too many. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of magnesium. What is wrong with it? (Picture: The symbol Mg with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: There are two dots too many. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of nitrogen. What is wrong with it? (Picture: The symbol N with dots around it: a pair on the top, a pair on the right, a single dot on the bottom, a single dot on the left.)Answer: There is one dot too many. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of oxygen. What is wrong with it? (Picture: The symbol O with dots around it: a pair on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: One dot is missing. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
A student drew this as the dot diagram of sulfur. What is wrong with it? (Picture: The symbol S with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Two dots are missing. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of aluminum. Which group of the periodic table do the dots point to? (Picture: The symbol Al with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom.)Answer: Group 13. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of argon. Which group of the periodic table do the dots point to? (Picture: The symbol Ar with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a pair on the left.)Answer: Group 18. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of chlorine. Which group of the periodic table do the dots point to? (Picture: The symbol Cl with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a single dot on the left.)Answer: Group 17. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of magnesium. Which group of the periodic table do the dots point to? (Picture: The symbol Mg with dots around it: a single dot on the top, a single dot on the right.)Answer: Group 2. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of phosphorus. Which group of the periodic table do the dots point to? (Picture: The symbol P with dots around it: a pair on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Group 15. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of silicon. Which group of the periodic table do the dots point to? (Picture: The symbol Si with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Group 14. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of sodium. Which group of the periodic table do the dots point to? (Picture: The symbol Na with dots around it: a single dot on the top.)Answer: Group 1. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
This is the dot diagram of sulfur. Which group of the periodic table do the dots point to? (Picture: The symbol S with dots around it: a pair on the top, a pair on the right, a single dot on the bottom, a single dot on the left.)Answer: Group 16. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 1. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top.)Answer: Hydrogen. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a pair on the left.)Answer: Neon. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a single dot on the left.)Answer: Fluorine. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a single dot on the bottom, a single dot on the left.)Answer: Oxygen. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Nitrogen. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Carbon. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom.)Answer: Boron. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right.)Answer: Beryllium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 2. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top.)Answer: Lithium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a pair on the left.)Answer: Argon. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a single dot on the left.)Answer: Chlorine. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a single dot on the bottom, a single dot on the left.)Answer: Sulfur. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Phosphorus. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Silicon. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom.)Answer: Aluminum. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right.)Answer: Magnesium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 3. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top.)Answer: Sodium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a pair on the left.)Answer: Krypton. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a pair on the bottom, a single dot on the left.)Answer: Bromine. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a pair on the right, a single dot on the bottom, a single dot on the left.)Answer: Selenium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a pair on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Arsenic. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom, a single dot on the left.)Answer: Germanium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right, a single dot on the bottom.)Answer: Gallium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top, a single dot on the right.)Answer: Calcium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
X stands for an element of period 4. Which one has this dot diagram? (Picture: The symbol X with dots around it: a single dot on the top.)Answer: Potassium. Source: Wikipedia, Valence electron, and the Purdue University chemistry review, Valence Electrons. Read 2026-10-01.
Molecules: read the structure 12
This is carbon dioxide's Lewis structure, CO₂. How many lone pairs does it show? (Picture: A C with an O on each side and a double line to each O. Each O has a pair of dots above it and a pair of dots below it.)Answer: Four. Source: Purdue University chemistry review, Lewis Structures, and Wikipedia, Octet rule. Read 2026-10-01.
This is carbon dioxide's Lewis structure, CO₂. How many shared pairs of electrons does it show? (Picture: A C with an O on each side and a double line to each O. Each O has a pair of dots above it and a pair of dots below it.)Answer: Four. Source: Purdue University chemistry review, Lewis Structures, and Wikipedia, Octet rule. Read 2026-10-01.
This is carbon dioxide's Lewis structure, CO₂. How many valence electrons does it show in all? (Picture: A C with an O on each side and a double line to each O. Each O has a pair of dots above it and a pair of dots below it.)Answer: 16 electrons. Source: Purdue University chemistry review, Lewis Structures, and Wikipedia, Octet rule. Read 2026-10-01.
This is the Lewis structure of ammonia, NH₃. How many lone pairs does it show? (Picture: An N with an H to its left, an H to its right and an H below it, a single line to each H, and a pair of dots above the N.)Answer: One. Source: Wikipedia, Lone pair, and the Purdue University chemistry review, VSEPR. Read 2026-10-01.
This is the Lewis structure of ammonia, NH₃. How many shared pairs of electrons does it show? (Picture: An N with an H to its left, an H to its right and an H below it, a single line to each H, and a pair of dots above the N.)Answer: Three. Source: Wikipedia, Lone pair, and the Purdue University chemistry review, VSEPR. Read 2026-10-01.
This is the Lewis structure of ammonia, NH₃. How many valence electrons does it show in all? (Picture: An N with an H to its left, an H to its right and an H below it, a single line to each H, and a pair of dots above the N.)Answer: 8 electrons. Source: Wikipedia, Lone pair, and the Purdue University chemistry review, VSEPR. Read 2026-10-01.
This is the Lewis structure of hydrogen, H₂. How many lone pairs does it show? (Picture: An H, a single line, and another H. No dots.)Answer: None. Source: Purdue University chemistry review, The Covalent Bond, and the Chem1 text, Lewis dot structures. Read 2026-10-01.
This is the Lewis structure of hydrogen, H₂. How many shared pairs of electrons does it show? (Picture: An H, a single line, and another H. No dots.)Answer: One. Source: Purdue University chemistry review, The Covalent Bond, and the Chem1 text, Lewis dot structures. Read 2026-10-01.
This is the Lewis structure of hydrogen, H₂. How many valence electrons does it show in all? (Picture: An H, a single line, and another H. No dots.)Answer: 2 electrons. Source: Purdue University chemistry review, The Covalent Bond, and the Chem1 text, Lewis dot structures. Read 2026-10-01.
This is the Lewis structure of water, H₂O. How many lone pairs does it show? (Picture: An O with an H on each side, a single line to each H, a pair of dots above the O and a pair of dots below it.)Answer: Two. Source: Wikipedia, Lone pair, and the UCLA Illustrated Glossary of Organic Chemistry, Lone pair. Read 2026-10-01.
This is the Lewis structure of water, H₂O. How many shared pairs of electrons does it show? (Picture: An O with an H on each side, a single line to each H, a pair of dots above the O and a pair of dots below it.)Answer: Two. Source: Wikipedia, Lone pair, and the UCLA Illustrated Glossary of Organic Chemistry, Lone pair. Read 2026-10-01.
This is the Lewis structure of water, H₂O. How many valence electrons does it show in all? (Picture: An O with an H on each side, a single line to each H, a pair of dots above the O and a pair of dots below it.)Answer: 8 electrons. Source: Wikipedia, Lone pair, and the UCLA Illustrated Glossary of Organic Chemistry, Lone pair. Read 2026-10-01.
Counting electrons and the rules 20
An ion's charge is 1−. What happens to the electron count of its Lewis structure?Answer: One electron is added. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many electrons do two atoms share in a double bond?Answer: 4 electrons. Source: Purdue University chemistry review, The Covalent Bond, and the Chem1 text, Lewis dot structures. Read 2026-10-01.
How many electrons does a hydrogen atom have around it in a Lewis structure?Answer: 2 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of carbon tetrachloride, CCl₄?Answer: 32 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of chlorine, Cl₂?Answer: 14 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of ethene, C₂H₄?Answer: 12 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of ethyne, C₂H₂?Answer: 10 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of hydrogen chloride, HCl?Answer: 8 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of hydrogen sulfide, H₂S?Answer: 8 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of methane, CH₄?Answer: 8 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of nitrogen, N₂?Answer: 10 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of oxygen, O₂?Answer: 12 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of the ammonium ion, NH₄⁺?Answer: 8 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of the chlorate ion, ClO₃⁻?Answer: 26 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
How many valence electrons go into the Lewis structure of the hydroxide ion, OH⁻?Answer: 8 electrons. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
In a finished Lewis structure, how many electrons surround most atoms other than hydrogen?Answer: 8 electrons. Source: Wikipedia, Octet rule, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
In a Lewis structure, what does one line between two atoms stand for?Answer: One pair of electrons that the two atoms share. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
In an electron dot diagram, what does each dot stand for?Answer: One valence electron. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
What is a lone pair?Answer: Two valence electrons on one atom that are not shared. Source: Wikipedia, Lone pair, and the UCLA Illustrated Glossary of Organic Chemistry, Lone pair. Read 2026-10-01.
Which electrons of an atom are left out of a dot diagram?Answer: The inner electrons, below the outermost shell. Source: Wikipedia, Lewis structure, and the Purdue University chemistry review, Lewis Structures. Read 2026-10-01.
This Lewis dot diagram quiz starts with single atoms: a symbol with one dot for each valence electron. Name the element, find its group, catch a diagram with a dot missing, then read four small Lewis structures.
Read the full guide
Three sets
Atoms shows a dot diagram and asks for the element, the group, or what is wrong with it. Molecules shows the Lewis structure of hydrogen, water, ammonia or carbon dioxide and asks for its lone pairs and shared pairs. Counting asks how many valence electrons a formula brings.
An electron dot diagram quiz too
Electron dot diagram is another name for the same picture. Here the dots go one to a side before any side gets a second, and the questions ask only how many there are.
Play or print
Tap a choice and the answer shows at once. A round is ten questions. After a round, Print lists its questions to trim or add to; the worksheet prints with the diagrams and, on a tick, a key.
Count the dots first: the number is the last digit of the group.
A line counts as two electrons, one shared pair.
Questions and answers
How many dots go in a Lewis dot diagram?
One dot for each valence electron: the group number in groups 1 and 2, its last digit in groups 13 to 18. Helium, with two, is the one exception. Oxygen, in group 16, gets six dots.
Is an electron dot diagram the same as a Lewis dot diagram?
Yes. Both names mean a chemical symbol with its valence electrons drawn as dots. A Lewis structure goes one step further and adds lines for the pairs of electrons that bonded atoms share.
What is a lone pair?
A pair of valence electrons that belongs to one atom and is not shared in a bond. It is drawn as two dots beside the atom. Water has two lone pairs, both on the oxygen.
Why does hydrogen have only two electrons in a Lewis structure?
Hydrogen's shell is full with two electrons, so it forms one bond and has no lone pairs. Most other atoms in these structures end up with eight electrons around them, which is the octet rule.
How do you count the valence electrons of an ion?
Add the valence electrons of every atom, then add one for each negative charge or take one away for each positive charge. The ammonium ion, NH₄⁺, has 5 + 4 − 1 = 8.