Given the following, how many protons are in an atom of chlorine? What is the atomic number of sodium?

Question

An atom of chlorine (Cl) has 6 more protons than an atom of sodium (Na). The atomic number of chlorine is 5 less than twice the atomic number of sodium. The atomic number of an element is equal to the number of protons per atom.

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Answer 1 · 2017-05-14T08:50:28

For #Cl#, #Z=17#.

#Z="the atomic number"#, the number of massive, positively charged nuclear particles. #Z# defines the identity of the element. For #Cl#, #Z=17#.

We are given that #Z_"Na"+6=Z_"Cl"#, and thus #Z_"Na"=11#.

And #2xxZ_"Na"-5=22-5=17=Z_"Cl"# as required.