Question

Write the expected ground-state electron configuration for the following: a. the element with one unpaired \(5 p\) electron that forms a covalent with compound fluorine b. the (as yet undiscovered) alkaline earth metal after radium

Short answer

The expected ground-state electron configurations are: a. Antimony (Sb): \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^3\) b. Undiscovered alkaline earth metal after radium: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^6 7s^2 5f^{14} 6d^{10} 7p^6\)

Step-by-step solution

Identify the element in part a

An element with an unpaired 5p electron would belong to Group 15 of the periodic table. The element in this group having a 5p electron is Antimony (Sb). We also know that this element forms a covalent compound with fluorine, which is a property of non-metals, further supporting our identification of Antimony.

Write the electron configuration for Antimony

Now that we have identified Antimony, we can write its electron configuration. Since Antimony has an atomic number of 51, we begin filling the orbitals with electrons from the lowest energy up. The electron configuration of Antimony in ground-state is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^3\]

Identify the next alkaline earth metal after radium

Alkaline earth metals are found in Group 2 of the periodic table. Radium (Ra) has atomic number 88. To find the next alkaline earth metal after radium, we move down the group and determine the atomic number of the new element. The new element would have an atomic number of 88 + 32 = 120 (it's 32 since you are skipping a period of 7f elements).

Write the electron configuration for the alkaline earth metal after radium

For the undiscovered alkaline earth metal with atomic number 120, we will again fill the orbitals with electrons starting from the lowest energy up. The electron configuration of this alkaline earth metal in ground-state is: \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^6 7s^2 5f^{14} 6d^{10} 7p^6\]

Key concepts

Understanding the Periodic Table

The periodic table is a comprehensive chart that arranges all known chemical elements in an organized way based on their atomic number, electron configurations, and recurring chemical properties. Elements are listed in order of increasing atomic number, which is the number of protons in an atom's nucleus. Each row on the table is known as a 'period', and each column is known as a 'group' or 'family'.

The structure of the periodic table reflects the electron configurations of the elements, showing how these configurations change as the atomic number increases. For instance, elements in the same group typically have similar valence electron configurations, leading to their similar chemical behaviors. Understanding how to read the periodic table is crucial when predicting the properties of elements, including their ability to form certain types of compounds, such as covalent compounds.

The Alkaline Earth Metals

Alkaline earth metals represent the elements located in Group 2 of the periodic table, which includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These metals are characterized by having two electrons in their outermost energy level, or shell, which they can lose to form compounds.

The general electron configuration for an alkaline earth metal is \[ns^2\], where 'n' represents the period of the element. They are highly reactive, though less so than the alkali metals in Group 1, and tend to form ionic compounds. For example, when combined with halogens, they commonly form salts. The exercise illustrates the predictive power of electron configurations by discussing the hypothetical next alkaline earth metal after radium, which would similarly follow the \[ns^2\] pattern.

Covalent Compounds

Covalent compounds are chemical compounds formed by the sharing of electron pairs between atoms. These pairs are known as covalent bonds. In contrast to ionic compounds, where electrons are transferred to achieve stable electron configurations, covalent compounds stabilize by sharing electrons.

The number of covalent bonds an atom can form is usually determined by the number of additional electrons needed to achieve a full outer shell, which is often eight—known as the octet rule. The electron configuration is vital in predicting an element's ability to form covalent bonds. For example, Antimony (Sb), mentioned in the exercise, has five electrons in its outermost 'p' orbital and requires three more to complete the octet, explaining its trivalent nature and tendency to form covalent compounds, such as those with fluorine.

Electron Configuration in Ground State

Ground state refers to the lowest energy state of an atom, where its electrons are in the closest possible orbitals to the nucleus according to the Pauli exclusion principle and Hund's rule. In the ground state, the electron configuration of an atom will fill the orbitals starting from the lowest energy level, following the aufbau principle (which means 'building up' in German).

The ground state electron configuration is essential for understanding the chemical reactivity and properties of an element. As seen in the provided solution, writing out the electron configuration of an element like Antimony (Sb) or an unpresented alkaline earth metal requires knowledge of the order in which orbitals are filled. Ground state configurations are used to determine everything from the type of bonds an element will form to its magnetic properties and behavior in a chemical reaction.