4. Atoms and Elements

Argon has three naturally occurring isotopes, with mass numbers 36, 38, and 40.a. Write the atomic symbol for each of these atoms.

How many neutrons are in an atom of magnesium-25 (${\mathrm{Mg}}^{25}$)? (Assume magnesium has atomic number $12$.)

Which nuclide has 18 neutrons?

Consider the following atoms in which X represents the chemical symbol of the element: (4.4, 4.5) ¹⁶₈X ¹⁶₉X ¹⁸₁₀X ¹⁷₈X ¹⁸₈Xc. Which atoms have the same mass number?

Copper has two naturally occurring stable isotopes, $C_{29}{u}^{63}$ and $C_{29}{u}^{65}$. Which statement correctly compares these two isotopes?

How many neutrons are in a neutral atom of sodium-23, $N_{23}^{11}$?

Isotopes of an element differ in the number of which subatomic particle?

An atom has 25 protons and 30 neutrons. Which element is it?

Complete the following table for the three naturally occurring isotopes of silicon, the major component in computer chips: (4.4, 4.5)

Consider the following atoms in which X represents the chemical symbol of the element: (4.4, 4.5) ¹⁶₈X ¹⁶₉X ¹⁸₁₀X ¹⁷₈X ¹⁸₈Xa. What atoms have the same number of protons?

Argon has three naturally occurring isotopes, with mass numbers 36, 38, and 40.b. How are these isotopes alike?

Consider the following atoms in which X represents the chemical symbol of the element: (4.4, 4.5) ¹⁶₈X ¹⁶₉X ¹⁸₁₀X ¹⁷₈X ¹⁸₈Xd. What atoms have the same number of neutrons?

Write the atomic symbol for the isotope with each of the following characteristics:c. 25 electrons and 28 neutrons