How many protons does a hydrogen have?

Expert Answers

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A hydrogen atom has one proton. The atomic number of an element is its number of protons. 

You can use information from the periodic table to determine the number of protons, electrons and neutrons in an atom.  A neutral atom has the same number of electrons as protons, so the number of electrons also equals the atomic number. The mass number of an atom equals the sum of protons and neutrons. (A periodic table usually gives the average mass of the isotopes. When rounded to the nearest whole number it's usually the mass of the most abundant isotope.) 

Here's an example:

The periodic table tells us that the atomic number of lithium is 3 and the mass is 6.94. A lithium atom has 3 protons and 3 electrons. The number of neutrons in the most abundant isotope is 7-3 = 4.

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