The electronic configuration of three elements $X$, $Y$, and $Z$ are $X - 2,8,7$; $Y - 2, 8, 2$; and $Z = 2,8$. Which of the following statements is correct?
A. $Y$ and $Z$ are metals
B. $Y$ and $X$ are non-metals
C. $X$ is a non-metal and $Y$ is a metal
D. $Y$ is a non-metal and $Z$ is a metal
Answer (2)
Determine the number of valence electrons for each element based on their electronic configuration.
Identify each element as a metal, non-metal, or noble gas based on their valence electrons.
Evaluate each statement based on the metallic/non-metallic nature of X, Y, and Z.
Conclude that the correct statement is: X is a non-metal and Y is a metal .
Explanation
Analyze the problem We are given the electronic configurations of three elements X, Y, and Z, and we need to determine which statement about their metallic or non-metallic nature is correct. The electronic configurations are:
X: 2, 8, 7
Y: 2, 8, 2
Z: 2, 8
Determine the valence electrons To determine whether an element is a metal, non-metal, or noble gas, we look at its valence electrons (electrons in the outermost shell).
X has 7 valence electrons. Elements with 7 valence electrons are typically non-metals (halogens).
Y has 2 valence electrons. Elements with 1, 2, or 3 valence electrons are typically metals.
Z has 8 valence electrons. Elements with 8 valence electrons have a complete octet and are noble gases (inert non-metals).
Evaluate the statements Now, let's evaluate the given statements:
A. Y and Z are metals. Y is a metal, but Z is a noble gas (non-metal). So, this statement is incorrect. B. Y and X are non-metals. X is a non-metal, but Y is a metal. So, this statement is incorrect. C. X is a non-metal and Y is a metal. This statement is correct. D. Y is a non-metal and Z is a metal. Y is a metal, and Z is a non-metal. So, this statement is incorrect.
Final Answer Therefore, the correct statement is C: X is a non-metal and Y is a metal.
Examples
Understanding the electronic configuration and valence electrons helps us predict the chemical properties of elements. For example, knowing that sodium (Na) has 1 valence electron (2,8,1) and chlorine (Cl) has 7 valence electrons (2,8,7) explains why they readily react to form sodium chloride (NaCl), a stable compound. Metals like sodium tend to lose electrons to achieve a stable configuration, while non-metals like chlorine tend to gain electrons. This principle is used in various applications, such as designing new materials and understanding chemical reactions.
Based on their electronic configurations, X has 7 valence electrons and is a non-metal, while Y has 2 valence electrons and is a metal. Z, with 8 valence electrons, is classified as a noble gas. The correct statement is therefore C: X is a non-metal and Y is a metal.
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