Valence electrons and electron dot diagrams for atoms
Grade 10 Science Worksheet
Circle the best answer, or write your answer on the line.
Nitrogen has 5 valence electrons and oxygen has 6. How many valence electrons go into the Lewis structure of nitrate, NO₃⁻, Ari?
Nitrogen has 5 valence electrons and hydrogen has 1. How many valence electrons go into the Lewis structure of ammonium, NH₄⁺, Bo?
Sulfur and oxygen each have 6 valence electrons. How many valence electrons go into the Lewis structure of sulfate, SO₄²⁻, Esme?
CO₂ has 16 valence electrons. Which Lewis structure uses all 16 and gives every atom an octet, Jun?
- O–C–O, with three lone pairs on each oxygen, so carbon has just 4
- O=C=O, with two lone pairs on each oxygen
- O=C=O, with one lone pair on each oxygen, so just 12 are used
NH₃ has 8 valence electrons. How many lone pairs does the nitrogen atom hold in its Lewis structure, Kira?
- 1: three N–H bonds use 6 electrons, leaving one pair
- 3, one lone pair for each bond
- 0, because nitrogen's electrons are used up in the bonds themselves
In H₂O, which statement about electrons around each atom is right, Luz?
- Each atom needs 8 electrons, so each hydrogen atom has 8 as well
- Oxygen has 8 electrons around it, and each hydrogen has 2
- Oxygen has 6 electrons around it, its valence count
Aluminum (2-8-3) and oxygen (2-6) form an ionic compound. What is its formula, Milo?
- Al₂O₃: 2 Al give away 6 electrons and 3 O take 6
- AlO: each Al gives 1 electron and O takes 1 electron
- Al₃O₂: three Al and two O balance the charges
Calcium (2-8-8-2) and nitrogen (2-5) form an ionic compound. What is its formula, Noah?
- Ca₃N₂: three Ca give 6 electrons and two N take 6
- CaN: one Ca gives 2 electrons to one N atom, so they balance
- Ca₂N₃: two Ca and three N balance the charges
Read this first
First ionization energy of group 1 metals (real data, CRC)
metal energy (kJ/mol) lithium 520 sodium 496 potassium 419 rubidium 403 cesium 376 Group 1 metals react more fiercely down the group. What explains it, Ren?
- Each has 1 valence electron, but it sits farther out and is easier to remove
- Each nucleus has more protons, so it holds its outer electron less tightly
- Each metal has more valence electrons down the group, so more of them can react
Oxygen and sulfur both have 6 valence electrons. What does that predict about their ions, Zee?
- Oxygen forms 2− but sulfur forms 6−, since sulfur is bigger
- Both form 2− ions, since each needs 2 electrons to reach 8
- Both form 6− ions, since each has 6 valence electrons