How to calculate molecular mass easily?
For example, what's the molecular mass of H₂O?
Why is valency important in writing formulas?
Why do we write H₂O, not HO₂?
What happens if we mix 1 mole of hydrogen with 1 mole of oxygen?
Do we directly get H₂O?
Why are chemical symbols universal?
Couldn't we just write “water” instead of H₂O?
What's the difference between atoms and molecules?
Are oxygen and O₂ the same thing?
Why is ozone O₃ instead of O₂?
Oxygen is O₂, so why does ozone have three atoms?
How to find the number of moles in a sample?
Example: How many moles in 36 g of water?
Why does rusting increase the mass of iron?
Isn't rust just corroded iron?
What are the main subatomic particles of an atom?
We hear about protons, neutrons, and electrons, but what exactly are they?
Why is an atom electrically neutral?
If atoms contain charges, why aren't they charged overall?
What is an isotope?
Why is carbon sometimes written as C-12 or C-14?
How is atomic number different from mass number?
Students often mix these up—what's the difference?
Why do different elements emit different colors in flame tests?
Sodium glows yellow, copper gives green — why?
What are energy shells or orbitals?
Why do electrons “orbit” at fixed distances?
What's the difference between an ion and an atom?
Why does sodium become Na⁺ in compounds?
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