Use Proton Count to Identify Atomic Number - Practice 2

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Atomic number is the number of protons in an atom's nucleus. Changing electron count makes an ion but does not change this atomic number. Neutron count distinguishes isotopes of the same element.

Worked example

A nucleus with 6 protons has atomic number 6, whether it contains 6 or 7 neutrons.

A nucleus count model labels 6 protons P and 6 neutrons N. Atomic number is 6; mass number is 12. Electrons are omitted and the layout is not a physical scale model.

Question 1 A model atom has 8 protons and 9 neutrons. What is its atomic number? Answer

Question 2 A model atom has 9 protons and 10 neutrons. What is its atomic number? Answer

Question 3 A model atom has 10 protons and 11 neutrons. What is its atomic number? Answer

Question 4 A model atom has 11 protons and 12 neutrons. What is its atomic number? Answer

Question 5 A model atom has 12 protons and 13 neutrons. What is its atomic number? Answer