Question

For each of the following numbers of electrons, give the formula of a positive ion that would have that number of electrons, and write the complete electron configuration for each ion. a. 10 electrons b. 2 electrons c. 18 electrons d. 36 electrons

Short answer

a. \(Ne^{0}\) - \(1s^2 2s^2 2p^6\) b. \(He^{0}\) - \(1s^2\) c. \(Ar^{0}\) - \(1s^2 2s^2 2p^6 3s^2 3p^6\) d. \(Kr^{0}\) - \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2\)

Step-by-step solution

Determine the element with the given number of electrons

Look up the element that has the same number of electrons in its neutral state, considering that the number of protons equals the number of electrons in a neutral atom. The atomic number of an element represents its number of protons. a. 10 electrons: Neutral atom - Neon (Ne), atomic number 10 b. 2 electrons: Neutral atom - Helium (He), atomic number 2 c. 18 electrons: Neutral atom - Argon (Ar), atomic number 18 d. 36 electrons: Neutral atom - Krypton (Kr), atomic number 36 Step 2:

Determine the number of electrons lost and the corresponding ion

Find how many electrons have been lost by comparing the atomic number with the given number of electrons, and then write the formula for the positive ion. a. 10 electrons: Ne, atomic number 10 - No electrons lost - \(Ne^{0}\) b. 2 electrons: He, atomic number 2 - No electrons lost - \(He^{0}\) c. 18 electrons: Ar, atomic number 18 - No electrons lost - \(Ar^{0}\) d. 36 electrons: Kr, atomic number 36 - No electrons lost - \(Kr^{0}\) Since no electrons were lost in any of the cases, all these ions are simply the neutral atoms. Step 3:

Write the electron configuration for each ion

To write the electron configuration for each ion, follow the order of energy levels and orbitals as dictated by the periodic table and use the Aufbau principle. a. 10 electrons (Neon): Electron configuration: \(1s^2 2s^2 2p^6\) b. 2 electrons (Helium): Electron configuration: \(1s^2\) c. 18 electrons (Argon): Electron configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6\) d. 36 electrons (Krypton): Electron configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2\) In conclusion, the positive ions and their corresponding electron configurations are: a. \(Ne^{0}\) - \(1s^2 2s^2 2p^6\) b. \(He^{0}\) - \(1s^2\) c. \(Ar^{0}\) - \(1s^2 2s^2 2p^6 3s^2 3p^6\) d. \(Kr^{0}\) - \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2\)

Key concepts

Chemical Elements

A chemical element is a pure substance consisting entirely of one type of atom, distinguished by its atomic number, which is the number of protons in its nucleus. Elements are the building blocks of all matter in the universe, and they vary in properties, which allow them to combine in various ways to create compounds.

For instance, when the exercise asks for a 10-electron ion, we consider the element neon (Ne), which is the 10th element on the periodic table. This atomic numbering ties directly to its unique physical and chemical properties caused by its constituent protons and electrons.

Understanding Ions

An ion is an atom that has lost or gained electrons, resulting in a net electric charge. In the given solution, we are asked to consider positive ions, which would result from an atom losing electrons. However, as noted in the solutions, each provided electron number corresponds to a noble gas element that has not lost electrons, hence they remain as neutral atoms rather than ions.

Atomic Structure

The atomic structure is what defines an element and determines its chemical behavior. An atom is composed of a nucleus containing protons and neutrons, with electrons orbiting the nucleus in various energy levels or shells.

The electron configuration of an atom or ion details the distribution of electrons among the energy levels. The step-by-step solution provided uses the Aufbau principle, which translates to 'building up' in German, to correctly fill orbitals with the electrons in increasing order of energy.

The Aufbau Principle

According to the Aufbau principle, electrons fill lower-energy orbitals before filling higher-energy ones. For example, helium with two electrons has the configuration of 1s², filling the lowest energy orbital first. Although no ions were formed in the exercises, understanding the atomic structure helps us predict how an atom might interact to form compounds or ions and its implications in chemical reactions.

Periodic Table

The periodic table is an organized chart of elements arranged by increasing atomic number, where each element is placed according to its chemical properties. The table is structured in rows called periods and columns known as groups or families. Elements with similar electron configurations and characteristics are in the same group.

The solutions to the exercise show that the noble gases (neon, helium, argon, and krypton) have no charge and fully filled electron shells corresponding to their positions on the periodic table.

Noble Gases

Noble gases are found in Group 18 of the periodic table and are known for their stability and lack of reactivity due to their complete valence electron shells. This is why they are often found in a neutral state, without the formation of ions, as indicated by the '0' charge after their symbols in the exercise (e.g., Ne⁰). The periodic table not only helps us determine electron configurations but also understand the trends and reactivities of various elements.