4. Atoms and Elements

An atom has $17$ protons and $18$ neutrons. Which element (and isotope) is it?

Gold has atomic number 79. How many neutrons are in an atom of the most common isotope, $A^u$ with mass number 197?

Which element is described by an atom that has 19 protons and 20 neutrons?

Which statement best defines a radioactive isotope?

Which element is represented by an atom with 20 protons and 20 neutrons?

Thallium has atomic number 81. How many neutrons are in an atom of thallium-205 (Tl-205)?

Which of the following best describes isotopes?

For an atom with mass number $A$ and atomic number $Z$, how do you determine the number of neutrons ($N$) in the atom?

Which isotope is described by an atom with 11 protons and 12 neutrons?

Which element has a most common isotope that contains 5 neutrons?

Which term describes atoms of the same element that have different numbers of neutrons?

Argon’s most abundant isotope is argon-40. How many neutrons are in one atom of ${}_{40}{}^{18}\mathrm{Ar}$?

What is the mass number of the isotope lithium-7?

Which element has 16 protons and 16 neutrons in its nucleus?

Which isotope of platinum contains 118 neutrons? (Platinum has atomic number $78$.)