What is the mass number of a potassium (K) atom that has 20 neutrons?

Consider the following table showing symbols, the number of protons, electrons, and neutrons, and the mass number. Each column represents a neutral atom.

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Fill in the third column of this table.

Mercury is in the 80th position in the periodic table. how many protons does it have?

Which subatomic particles contribute to an atom's mass number but not its atomic number?

What type of atomic particles will you find inside of the nucleus of an atom?

If an atom has 35 protons in the nucleus, how many electrons will it have orbiting the nucleus?

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?