Chapter 9: Problem 50
Write full electron configurations for each element. (a) \(\mathrm{N}\) (b) \(\mathrm{Mg}\) (c) \(\mathrm{Ar}\) (d) Se
Short Answer
Expert verified
The electron configurations are: (a) N: 1s2 2s2 2p3, (b) Mg: 1s2 2s2 2p6 3s2, (c) Ar: 1s2 2s2 2p6 3s2 3p6, (d) Se: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4.
Step by step solution
01
Understanding Electron Configuration
To write an electron configuration for an element, first determine its atomic number from the periodic table. This gives the total number of electrons to distribute. The distribution follows the order of energy levels and sublevels, according to the Aufbau principle, from lower to higher energy: 1s, 2s, 2p, 3s, 3p, 4s, and so on.
02
Electron Configuration for Nitrogen (N)
Nitrogen has an atomic number of 7, therefore it has 7 electrons to distribute. Following the Aufbau principle: 1s can hold 2, 2s can hold 2 and 2p can hold up to 6 electrons. The electron configuration will be 1s2 2s2 2p3.
03
Electron Configuration for Magnesium (Mg)
Magnesium has an atomic number of 12, meaning it has 12 electrons. Distribution of these electrons follows: 1s2 2s2 2p6 3s2, filling the 3s sublevel after 2p.
04
Electron Configuration for Argon (Ar)
Argon's atomic number is 18, indicating 18 electrons. The electrons fill up to 3p sublevel: 1s2 2s2 2p6 3s2 3p6.
05
Electron Configuration for Selenium (Se)
Selenium has an atomic number of 34, which means it has 34 electrons. The electronic configuration goes up to the 4p sublevel: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Aufbau Principle
The Aufbau principle is a fundamental concept in understanding how electrons are arranged within an atom. At its core, this principle states that electrons will fill the lowest energy levels first before moving on to higher ones. An easy way to visualize it is by imagining a building being constructed from the ground up, with each new floor representing a higher energy level for the electrons.
According to the Aufbau principle, we begin by filling the 1s sublevel, because it's the lowest energy level. Once the 1s sublevel is filled with its maximum of two electrons, we proceed to the 2s sublevel, and so on. This process is crucial for determining the electron configuration of elements, as it guides us in distributing the electrons in the correct order of sublevels such as 1s, 2s, 2p, 3s, 3p, and 4s. Keep in mind that there are exceptions to the rule, primarily involving d and f sublevels, due to their very close energy levels.
According to the Aufbau principle, we begin by filling the 1s sublevel, because it's the lowest energy level. Once the 1s sublevel is filled with its maximum of two electrons, we proceed to the 2s sublevel, and so on. This process is crucial for determining the electron configuration of elements, as it guides us in distributing the electrons in the correct order of sublevels such as 1s, 2s, 2p, 3s, 3p, and 4s. Keep in mind that there are exceptions to the rule, primarily involving d and f sublevels, due to their very close energy levels.
Atomic Number
The atomic number of an element is a key concept in chemistry that reflects the number of protons in the nucleus of an atom. This number is crucial because it is also equal to the number of electrons in a neutral atom, providing the foundation for determining an element's electron configuration. For instance, nitrogen (N) has an atomic number of 7, meaning it has seven protons and, when neutral, seven electrons.
The determination of the atomic number is the first step in writing electron configurations because it tells us exactly how many electrons we need to distribute according to the rules of the Aufbau principle and energy sublevels. The atomic number also uniquely identifies an element and determines its position on the periodic table, which leads to an understanding of its chemical properties.
The determination of the atomic number is the first step in writing electron configurations because it tells us exactly how many electrons we need to distribute according to the rules of the Aufbau principle and energy sublevels. The atomic number also uniquely identifies an element and determines its position on the periodic table, which leads to an understanding of its chemical properties.
Periodic Table
The periodic table is not just a chart of elements; it's a comprehensive map that provides a wealth of information about the chemical and physical properties of elements. Understanding the layout of the periodic table helps to predict the electron configurations of elements. Elements are ordered by increasing atomic number, and this sequential order reflects the manner in which the energy sublevels are filled.
The table is arranged in rows called periods and columns called groups. Elements in the same group have similar electron configurations in their outermost shells, leading to similar chemical properties. For example, the noble gases found in Group 18 have filled valence shells, making them particularly stable. The periodic table also divides elements into blocks (s, p, d, f), corresponding to the sublevel that is being filled by the last electron added. Hence, understanding the periodic table's structure is essential for determining an element's electron configuration.
The table is arranged in rows called periods and columns called groups. Elements in the same group have similar electron configurations in their outermost shells, leading to similar chemical properties. For example, the noble gases found in Group 18 have filled valence shells, making them particularly stable. The periodic table also divides elements into blocks (s, p, d, f), corresponding to the sublevel that is being filled by the last electron added. Hence, understanding the periodic table's structure is essential for determining an element's electron configuration.
Energy Sublevels
Atoms are made up of energy levels, which can be divided further into sublevels designated as s, p, d, and f. Each sublevel has a different capacity for electrons: 's' can hold 2, 'p' can hold 6, 'd' can hold 10, and 'f' can hold 14. The energy sublevels fill in a specific order based on their increasing energy, as dictated by the Aufbau principle.
It's important to note the order in which these sublevels are usually filled: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, and so on, zigzagging between the different levels. However, the exact filling order can sometimes vary due to small differences in energy levels, causing a switch in the expected order (like 4s filling before 3d). When writing electron configurations, one must pay attention to the correct sequence of filling these sublevels to accurately represent the distribution of electrons in an atom.
It's important to note the order in which these sublevels are usually filled: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, and so on, zigzagging between the different levels. However, the exact filling order can sometimes vary due to small differences in energy levels, causing a switch in the expected order (like 4s filling before 3d). When writing electron configurations, one must pay attention to the correct sequence of filling these sublevels to accurately represent the distribution of electrons in an atom.
