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1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

2. Atoms & Elements

Ions

General Chemistry

2. Atoms & Elements

Ions

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Multiple Choice

How many electrons are present in an O^{2-} ion?

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Identify the atomic number of oxygen (O), which represents the number of protons and, in a neutral atom, also the number of electrons. For oxygen, the atomic number is 8.

Understand that the O^{2-} ion has gained 2 extra electrons compared to the neutral oxygen atom, because the negative charge indicates additional electrons.

Calculate the total number of electrons in the O^{2-} ion by adding the 2 extra electrons to the 8 electrons of the neutral oxygen atom.

Write the expression for the total electrons as: $8 + 2$.

Conclude that the number of electrons in the O^{2-} ion is the sum from the previous step.