Question

Element X, which has a valence shell configuration of \(\mathrm{n} s^{2} \mathrm{n} p^{4},\) was isolated in a laboratory. Which of the following statements is(are) true concerning element X? a. Element X has chemical properties similar to those of the halogens. b. Element X has six valence electrons. c. When element \(X\) is reacted with calcium, the compound formed would most likely have the formula \(\mathrm{Ca}_{2} \mathrm{X}\). d. Element X needs to gain two electrons to attain a noble gas electron configuration.

Short answer

The true statements concerning element X are: b. Element X has six valence electrons. d. Element X needs to gain two electrons to attain a noble gas electron configuration.

Step-by-step solution

Determine Element X's Number of Valence Electrons

Element X has the electron configuration $\mathrm{n} s^{2} \mathrm{n} p^{4}$. The valence electrons are the outermost electrons, which are located in the highest energy level. In this case, there are: - 2 electrons in the s orbital: \(s^2\) - 4 electrons in the p orbital: \(p^4\) Therefore, element X has a total of 2 + 4 = 6 valence electrons.

Decide whether Element X's chemical properties are similar to halogens

Halogens are elements in Group 17 in the periodic table. They all have 7 valence electrons (\(ns^2np^5\) electron configuration) and, as a result, they are highly reactive, tending to gain one electron and form a -1 anion to achieve a noble gas configuration. Since element X has 6 electrons and not 7, its chemical properties would not be similar to those of the halogens and statement a is false.

Verify if statement b is true or false

As we determined in Step 1, Element X has 6 valence electrons (\(ns^2np^4\)). Therefore, statement b is true.

Predict the formula of the compound formed between Calcium and Element X

To determine the formula of the compound, we need to find the charge of the ions that would be formed. Calcium (Ca) is an alkaline earth metal in Group 2 and typically forms a +2 cation (Ca²⁺) by losing its two valence electrons. Element X has 6 valence electrons and is likely to gain 2 electrons (as stated in statement d) to achieve a noble gas configuration, thus forming a -2 anion (X²⁻). When we pair the ions to form a neutral compound, the formula would be \(\mathrm{CaX}\). Therefore, statement c is false, as the most likely formula of the compound formed is \(\mathrm{CaX}\) and not \(\mathrm{Ca}_{2} \mathrm{X}\).

Determine if Element X needs to gain two electrons to attain a noble gas configuration

We already established that element X has 6 valence electrons (\(ns^2np^4\)). Since noble gases have a full valence shell (\(ns^2np^6\), except for helium), element X needs to gain 2 electrons to reach this configuration. Therefore, statement d is true. #Conclusion# The true statements concerning element X are: b. Element X has six valence electrons. d. Element X needs to gain two electrons to attain a noble gas electron configuration.

Key concepts

Understanding the Periodic Table

The periodic table is a crucial tool used to predict the characteristics and chemical behavior of elements. It is systematically arranged in rows, known as periods, and columns, called groups or families, based on atomic number and electron configuration.

Each row indicates a new principal energy level for electrons. As you move from left to right across a period, the number of valence electrons increases until it reaches a noble gas, which has a full valence shell. The groups, on the other hand, contain elements with similar valence electron arrangements and, correspondingly, similar chemical properties.

For example, element X with a valence shell configuration of (s^2)(p^4) is part of Group 16, also known as chalcogens. These elements typically have six valence electrons, which influences their tendency to form certain types of compounds, typically by gaining two electrons to achieve a stable configuration.

Deciphering Electron Configuration

Electron configuration specifies the distribution of electrons among the orbitals of an atom. Understanding this configuration is key to predicting how an element will react chemically. The most stable (and least reactive) electron configuration is that of a noble gas, with a full valence shell.

In the context of element X, its electron configuration (s^2)(p^4) indicates that it has 6 valence electrons. This configuration helps determine that element X is two electrons short of reaching a stable noble gas configuration, which would be represented as (s^2)(p^6). The necessity for element X to gain two electrons for stability drives many of its chemical reactions and the types of ionic compounds it forms.

Chemical Properties and Reactivity

Chemical properties are based largely on an element's ability to form bonds and its reaction to other substances. These properties are influenced by valence electrons, as they are the ones involved in chemical bonding.

An element's tendency to lose, gain, or share electrons determines its reactivity. For instance, halogens are highly reactive because they need to gain just one electron to reach a noble gas configuration. Conversely, noble gases are not reactive because their valence shell is already full.

The chemical properties of element X differ from those of halogens because it requires two electrons to reach a stable state, not just one. This means element X would more likely participate in different types of chemical reactions than the halogens would.

Ionic Compounds and Bond Formation

Ionic compounds form when atoms transfer electrons from one to another, creating charged ions that attract each other due to opposite charges. Metals often form positive ions (cations) while nonmetals form negative ions (anions).

As predicted in the exercise, when element X combines with calcium, it is likely to embark on the transfer of electrons. Calcium, being an alkaline earth metal, will typically lose its two valence electrons to form a Ca²⁺ ion. Element X, with six valence electrons, tends to gain two electrons to form an X²⁻ ion. When these ions combine, they form an electrically neutral compound: CaX.

The propensity for element X to form an anion and its resultant compound with calcium is a direct consequence of its valence electron configuration, illustrating the intimate link between electron configuration and the formation of ionic compounds.