Question

Fill in the gaps in the following table, assuming each column represents a neutral atom: $$ \begin{array}{|l|c|c|c|c|c|} \hline \text { Symbol } & { }^{65} \mathrm{Zn} & & & & \\ \hline \text { Protons } & & 44 & & & 92 \\ \hline \text { Neutrons } & & 57 & 49 & & \\ \hline \text { Electrons } & & & 38 & 47 & \\ \hline \text { Mass no. } & & & & 108 & 235 \\ \hline \end{array} $$

Short answer

} & {?} & \mathrm{U} \\\ \hline \text { Protons } & 30 & 44 & {?} & {?} & 92 \\\ \hline \text { Neutrons } & 35 & 57 & 49 & {?} & 143 \\\ \hline \text { Electrons } & 30 & 44 & 38 & 47 & 92 \\\ \hline \text { Mass no. } & 65 & 101 & {?} & 108 & 235 \\\ \hline \end{array} $$

Step-by-step solution

Identify the element based on the number of protons

Given the element symbol and number of protons, we can identify the name of the element. Here we have: - 65^Zn: This element is Zinc, and the atomic number (number of protons) is 30. - 44 protons: The element with 44 protons is Ruthenium (Ru). - 92 protons: The element with 92 protons is Uranium (U).

Fill in the missing proton values based on the element symbols

Now that we've identified the elements, let's fill in the missing proton information: - 65^Zn: Since Zinc(Zn) has 30 protons, we can fill in 30 protons for the first column. - Ru: Since Ruthenium(Ru) has 44 protons, we can leave that value as is. - U: Since Uranium(U) has 92 protons, we can leave that value as is.

Calculate the number of neutrons using the mass number

We can compute the number of neutrons using the mass number and the number of protons: - 65^Zn: Mass number is 65 and has 30 protons, so the number of neutrons is 65 - 30 = 35. - Ru: Mass number is not given. - U: Mass number is 235 and has 92 protons, so the number of neutrons is 235 - 92 = 143.

Calculate the mass number using the number of neutrons and protons

For given neutrons and protons, we can calculate the mass number: - Ru: 44 protons and 57 neutrons, so the mass number is 44 + 57 = 101. - Next element: Protons are not given, so we can't calculate the mass number.

Calculate the number of electrons using the number of protons

Since the number of electrons is equal to the number of protons in a neutral atom, we can fill in the missing electron values: - 65^Zn: 30 protons, so 30 electrons. - Ru: 44 protons, so 44 electrons. - U: 92 protons, so 92 electrons.

Combine all the calculated information in the table

Here's the completed table with the missing information filled in: $$ \begin{array}{|l|c|c|c|c|c|} \hline \text { Symbol } & { }^{65} \mathrm{Zn} & \mathrm{Ru} & {?} & {?} & \mathrm{U} \\\ \hline \text { Protons } & 30 & 44 & {?} & {?} & 92 \\\ \hline \text { Neutrons } & 35 & 57 & 49 & {?} & 143 \\\ \hline \text { Electrons } & 30 & 44 & 38 & 47 & 92 \\\ \hline \text { Mass no. } & 65 & 101 & {?} & 108 & 235 \\\ \hline \end{array} $$

Key concepts

Understanding Atomic Number

The atomic number is a fundamental property of an atom that determines the identity of an element. More simply, it’s the number of protons found in the nucleus of an atom. Since each element has a unique number of protons, the atomic number is crucial for distinguishing one element from another.

For instance, in the exercise, Zinc (Zn) has an atomic number of 30, which means it contains 30 protons. This atomic number is critical for the chemical properties and the place of Zinc in the periodic table. In a neutral atom, the atomic number also tells us the number of electrons. Therefore, with an atomic number of 30, a neutral Zinc atom also has 30 electrons, balancing the positive charge of the protons with an equal number of negative charges.

Mass Number and Its Significance

The mass number, unlike the atomic number, is not fixed for an element -- it is the total number of protons and neutrons in an atom's nucleus. The significance of the mass number lies in its ability to tell isotopes of the same element apart.

Calculating is simple: just add the number of protons to the number of neutrons. The mass number is important because it gives us the 'weight' of the nucleus and, by extension, the atom. In the given exercise, for instance, the mass number of Uranium (U) is mentioned as 235, indicating it has a combined total of 235 protons and neutrons in its nucleus.

Isotopes Explained

Isotopes are variants of a particular chemical element that have the same number of protons (and thus the same atomic number) but different numbers of neutrons. This means that while they are the same element, they have different mass numbers.

Isotopes can be stable or radioactive, with the latter having a propensity to decay over time, emitting radiation. For instance, in the exercise, if another isotope of Zinc had more or less than 35 neutrons, it would still be Zinc because the atomic number (30 protons) remains unchanged, but it would be a different isotope of Zinc, with a different mass number.

Neutral Atoms: Balancing Charges

Neutral atoms maintain a balance between protons and electrons, which means they carry no net charge. The number of electrons, negatively charged, equals the number of protons, positively charged, in a neutral atom. This balance ensures the overall electric neutrality of the atom.

For example, the Zinc atom from our exercise contains 30 electrons, the same as its atomic number of protons, thus keeping it neutral. If an atom loses or gains electrons, it becomes an ion, carrying a positive or negative charge, respectively. Understanding the concept of neutral atoms is essential because it plays a critical role in chemical reactions, where elements often react to achieve a neutral state.