Why isn't the mass number just the neutrons?
An atom with 17 protons and 18 neutrons: is its mass number 35 or 18? And what is its charge? Work through the counting rules one blank at a time.
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1 lesson for “Atoms, ions and isotopes”
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Does sodium share its electron with chlorine?
NaCl is table salt, but is it held together by sharing or by moving an electron? Trace the transfer and the attraction.
Try this lessonWhat is the second product of acid plus base?
Acid and base do not vanish. Their ions trade partners and become a salt and water. Fill in the two products.
Try this lessonIs pH 3 more acidic than pH 5?
pH 7 is the midway point. Learn which direction means acid strength, and why pH 3 and pH 5 differ by a hundred times.
Try this lessonIs carbon ever created or destroyed?
You said burning makes new carbon. The atoms were already here; burning just moves stored carbon back into the air.
Try this lessonIs it sodium chloride or sodium chlorine?
Two words and two numbers stand between you and a correct ionic name or formula. Learn the rule, then balance the charges.
Try this lessonWhen two nonmetals meet, do they share or transfer?
Hydrogen cannot pull an electron away from hydrogen, so the two atoms do something smarter: they share. Count the pairs.
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