Problem 71 - Chemistry: The Central Science

Question

Identify the specific element that corresponds to each of the following electron configurations: (a) \(1 s^{2} 2 s^{2}\), (b) \(1 s^{2} 2 s^{2} 2 p^{4}\), (c) \([\mathrm{Ar}] 4 s^{1} 3 d^{5}\), (d) \([\mathrm{Kr}] 5 s^{2} 4 d^{10} 5 p^{4}\) (e) \(1 s\).

Step-by-Step Solution

Answer

The elements corresponding to the given electron configurations are: (a) Beryllium (Be) for \(1 s^{2} 2 s^{2}\) (b) Oxygen (O) for \(1 s^{2} 2 s^{2} 2 p^{4}\) (c) Chromium (Cr) for \([\mathrm{Ar}] 4 s^{1} 3 d^{5}\) (d) Tellurium (Te) for \([\mathrm{Kr}] 5 s^{2} 4 d^{10} 5 p^{4}\) (e) Hydrogen (H) for \(1 s\)

Step 1: (a) Identify the element with the electron configuration: \(1 s^{2} 2 s^{2}\)

Count the total electrons in this configuration: \(2 + 2 = 4\). Now, look for the element with 4 electrons in the periodic table, which is Beryllium (Be).

Step 2: (b) Identify the element with the electron configuration: \(1 s^{2} 2 s^{2} 2 p^{4}\)

Count the total electrons in this configuration: \(2 + 2 + 4 = 8\). Now, look for the element with 8 electrons in the periodic table, which is Oxygen (O).

Step 3: (c) Identify the element with the electron configuration: \([\mathrm{Ar}] 4 s^{1} 3 d^{5}\)

Argon has 18 electrons. Now add the extra electrons in this configuration: \(18 + 1 + 5 = 24\). Look for the element with 24 electrons in the periodic table, which is Chromium (Cr).

Step 4: (d) Identify the element with the electron configuration: \([\mathrm{Kr}] 5 s^{2} 4 d^{10} 5 p^{4}\)

Krypton has 36 electrons. Now add the extra electrons in this configuration: \(36 + 2 + 10 + 4 = 52\). Look for the element with 52 electrons in the periodic table, which is Tellurium (Te).

Step 5: (e) Identify the element with the electron configuration: \(1 s\)

There is only 1 electron in this configuration. Look for the element with 1 electron in the periodic table, which is Hydrogen (H).

Key Concepts

Periodic Table

The periodic table is like a map of the elements. It organizes all known chemical elements in a way that makes it easy to identify an element's properties and see how they relate to others. Elements are arranged in order of increasing atomic number, which means the number of protons in an atom's nucleus. This arrangement not only helps in identifying the elements but also shows their recurring (or "periodic") chemical properties.
Elements in the same column, or group, have similar chemical behaviors because they have the same number of electrons in their outermost shell. For instance, all elements in the first column (which includes hydrogen and lithium) have one electron in their outer shell and are highly reactive. This structure is immensely helpful in identifying elements based on their properties or an electron configuration, which is essentially a snapshot of an element's "map location."
The periodic table is divided into rows, called periods, and columns called groups or families. The atomic structure and the elements' chemical identity can be determined by their position in this table, making it a central tool in chemistry.

Element Identification

Identifying an element involves understanding its electron configuration, which is like its unique code. Electron configuration shows where electrons exist around the nucleus of an atom. These electrons fill up "shells" or "orbitals" in a specific order. A basic understanding of this order helps unearth the true identity of any element.
To identify an element, sum up all the electrons described by its electron configuration. The total number of electrons equals the atom's atomic number, which directly points to its identity on the periodic table. For example, an electron configuration of

• \(1s^{2} 2s^{2} 2p^{4}\) indicates Oxygen, as adding up these electrons gives 8.
• \(1s^{2} 2s^{2}\) points to Beryllium with 4 electrons.

Each element's configuration maps out its electron placement, thus revealing its chemical traits and making identification straightforward.

Atomic Structure

Atomic structure refers to the essence of what makes up an atom and how the arrangement of its core components—protons, neutrons, and electrons—defines a specific element. The nucleus, located at the center of the atom, contains protons and neutrons. The number of protons, known as the atomic number, dictates the identity of the element.
Electrons orbit around the nucleus in regions called electron shells or energy levels. These shells fill up with electrons in a specific sequence, known as their electron configuration. The configuration shows the distribution of electrons among the available levels and orbitals.

• Each shell can hold a certain number of electrons before moving to the next: the first shell can hold 2, the second can hold up to 8, and so on.
• The number of electrons in an atom usually matches the number of protons, making the atom electrically neutral.
• A full valence shell (outermost shell) leads to an element being chemically inert, like the noble gases.

Understanding atomic structure is vital for grasping why elements behave the way they do and how they interact with one another in chemical reactions.