Question

Given the valence electron orbital level diagram and the description, identify the element or ion. a. A ground state atom b. An atom in an excited state (assume two electrons occupy the \(1 s\) orbital) c. A ground state ion with a charge of -1

Short answer

For case a, identify the element by counting the number of electrons in the given valence electron level diagram and finding the corresponding element on the periodic table. For case b, calculate the total number of electrons by counting those in the level diagram and adding two assumed \(1s\) electrons. Identify the element by finding the corresponding one on the periodic table. For case c, count the number of electrons in the given valence electron level diagram, add one to account for the -1 charge, and identify the element or ion by finding the corresponding one on the periodic table.

Step-by-step solution

Case a: Ground State Atom

Since the atom is in its ground state, all electrons will occupy the lowest possible energy levels. Each energy level can be represented as \(n\), where \(n=1,2,3, ...\). The number of electrons that each energy level can hold is given by the formula \(2n^2\). Based on the given valence electron level diagram and the description, we can write down the electron configuration: 1. Count the number of electrons in the valence electron level diagram. 2. Determine the element that corresponds to this electron configuration on the periodic table. For case a, identify the element with the electron configuration provided in the valence electron orbital level diagram.

Case b: Excited State Atom

Since the atom is in an excited state, at least one electron will occupy a higher energy level than its normal ground state. However, we are assuming there are two electrons occupying the \(1s\) orbital. Therefore, we need to determine the total number of electrons, including these two \(1s\) electrons, as follows: 1. Count the number of electrons in the valence electron level diagram. 2. Add the two assumed \(1s\) electrons. 3. Determine the element that corresponds to this electron configuration on the periodic table. For case b, identify the element with the corrected electron configuration.

Case c: Ground State Ion with a Charge of -1

In this case, we have a ground state ion with a charge of -1. A negative charge means that the ion has gained one electron. All the electrons will occupy the lowest possible energy levels. We can determine the total number of electrons as follows: 1. Count the number of electrons in the valence electron level diagram. 2. Add one electron to account for the -1 charge. 3. Determine the element that corresponds to this electron configuration on the periodic table. For case c, identify the element or ion with the corrected electron configuration and take into account the -1 charge.

Key concepts

Ground State Atom

A ground state atom represents an atom in its most stable, energy-efficient configuration. Electrons within a ground state atom occupy the lowest available energy levels, following the principle known as the Aufbau principle. This principle lays the foundation for understanding the electron configuration of atoms.

In a ground state atom, the number of electrons corresponds directly to the atomic number of the element. This means that we can identify an element by its electron configuration. For example, if an atom has two electrons in the 1s subshell (the innermost shell) and no other electrons, it will be a helium atom because helium's atomic number is 2. To elucidate this, let's imagine viewing an orbital level diagram. Each energy level can be symbolized by an 'n', where 'n' could be 1, 2, 3, and so forth - representing the principal quantum number. According to the rule given by the formula \(2n^2\), these levels dictate how many electrons they can house. Generally, you should see electrons paired up in orbitals, signifying their spin-opposite nature.

For students, recognizing and writing down the electron configuration of ground state atoms is an essential skill. It aids in visualizing the structural framework of an atom and understanding how electron transitions work.

Excited State Atom

In contrast to a ground state atom, an excited state atom has electrons that have absorbed energy and 'jumped' to higher energy levels. These configurations are less stable than their ground state counterparts and tend to return to a ground state, releasing energy in the process.

An atom is considered excited when at least one electron moves to a higher energy orbital than expected. Excited states are typically generated by energy absorption, either through heat, light, or electrical energy. For instance, when an atom absorbs a photon, an electron can get enough energy to move from the 1s to the 2s orbital, creating an excited state. This state is temporary, and the electron will eventually fall back down, emitting energy, often as light. This is the basic mechanism behind phenomena such as neon lights and lasers.

In solving problems related to excited state atoms, you must carefully consider the given information, as an excited state electron configuration will look different from a ground state one. Counting the electrons accurately and keeping track of their placements is vital, especially when unusual situations are described, such as having more than the typical number of electrons in a specific orbital.

Valence Electrons

Valence electrons are the electrons that reside in the outermost shell of an atom and play a pivotal role in chemical bonding and the physical properties of elements. These are the electrons involved in forming bonds with other atoms because they have more space to interact since they are farthest from the nucleus.

Understanding valence electrons is important for understanding how elements interact and combine to form chemical compounds. The group (vertical column) on the periodic table can quickly tell you how many valence electrons an element has. For instance, elements in Group 1 have one valence electron, resulting in certain chemical properties like reactivity with water. Likewise, the noble gases in Group 18 have full valence shells, making them generally unreactive.

Determining the number of valence electrons helps predict how an atom will bond, whether it will share electrons (covalent bonds), donate electrons (ionic bonds), or exhibit some other form of chemical interaction. For students, mastering this concept means being able to determine how elements interact and what kinds of molecules or ionic compounds they can form.

Periodic Table

The periodic table is not just a table with elements; it is a comprehensive map that reveals the underlying principles of elemental properties and behaviors. It effectively categorizes all known elements into groups and periods based on their atomic structures and properties.

Within this table, elements are listed in order of increasing atomic number (the number of protons in the nucleus). Elements that share common properties are arranged in the same column, known as a group, while rows are referred to as periods. The position of an element on the periodic table can reveal a wealth of information about it, including its valence electron configuration. This is because elements in the same group generally have the same number of valence electrons.

Understanding how to read and interpret the periodic table is crucial for students as it assists in predicting how elements will behave in chemical reactions. It also helps when deducing the electron configuration of atoms, as highlighted in the previous exercises. By knowing which group and period an element is in, you can make educated guesses about its properties and how it will interact with other elements.