Problem 182 - Introductory Chemistry Atoms First

Question

Taking all configurations to be for neutral atoms, identify the elements having the following electron configurations: (a) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{10} 4 s^{2} 4 p^{5}\) (b) \(1 s^{2} 2 s^{2} 2 p^{1}\) (c) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{10} 4 p^{6} 5 s^{1}\) (d) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{10} 4 p^{6} 5 s^{2} 4 d^{10} 5 p^{6} 6 s^{2} 4 f^{14} 5 d^{10} 6 p^{6}\) \(7 s^{2} 6 d^{1} 5 f^{3}\) (e) \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2}\)

Step-by-Step Solution

Answer

The elements with the given electron configurations are: (a) Bromine (Br) (b) Boron (B) (c) Rubidium (Rb) (d) Fermium (Fm) (e) Calcium (Ca)

Step 1: (a) Identify Element for 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵ Configuration

Find the total number of electrons in the configuration by adding the superscripts: \(2 + 2 + 6 + 2 + 6 + 10 + 2 + 5 = 35\) The atomic number of the element is 35, which corresponds to Bromine (Br) in the periodic table.

Step 2: (b) Identify Element for 1s² 2s² 2p¹ Configuration

Find the total number of electrons in the configuration by adding the superscripts: \(2 + 2 + 1 = 5\) The atomic number of the element is 5, which corresponds to Boron (B) in the periodic table.

Step 3: (c) Identify Element for 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ Configuration

Find the total number of electrons in the configuration by adding the superscripts: \(2+2+6+2+6+2+10+6+1 = 37\) The atomic number of the element with this electron configuration is 37, which corresponds to Rubidium (Rb) in the periodic table.

Step 4: (d) Identify Element for Complex Configuration

Find the total number of electrons in the configuration by adding the superscripts: \(2 + 2 + 6 + 2 + 6 + 2 + 10 + 6+ 2 + 10 + 6 + 2 + 14 + 10 + 6 + 2 + 1 + 3 = 100\) The atomic number of the element with this electron configuration is 100, which corresponds to Fermium (Fm) in the periodic table.

Step 5: (e) Identify Element for 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² Configuration

Find the total number of electrons in the configuration by adding the superscripts: \(2 + 2 + 6 + 2 + 6 + 2 = 20\) The atomic number of the element with this electron configuration is 20, which corresponds to Calcium (Ca) in the periodic table. Thus, we have identified the elements in the given electron configurations: (a) Bromine (Br) (b) Boron (B) (c) Rubidium (Rb) (d) Fermium (Fm) (e) Calcium (Ca)

Key Concepts

Atomic Number

The atomic number is fundamental in understanding an element's identity. It represents the number of protons in an atom's nucleus and is unique for every element.
For neutral atoms, the atomic number also equals the number of electrons. This number determines an element's position on the periodic table.
It's significant because it helps in identifying elements based on their electron configurations by simply summing the number of electrons (given by the superscripts in an electron configuration).
For example, an atomic number of 35 leads us directly to bromine on the periodic table. Remember, finding the total number of electrons is your key to figuring out the atomic number.

Periodic Table

The periodic table is a comprehensive chart of all chemical elements arranged according to their atomic number, electron configurations, and recurring chemical properties.
In this table, elements are placed in rows, called periods, and columns, called groups.

• Periods indicate number of electron shells.
• Groups show elements with similar chemical behaviors.

Learning the periodic table might seem daunting, but it plays a crucial role in chemistry.
It helps us understand and predict the relationships between the elements, including their chemical reactions and properties.
We can locate elements like bromine, boron, and rubidium quickly by identifying their atomic numbers and the periodic table guides us in confirming these identities.

Bromine

Bromine is a fascinating and important element, symbolized as Br. With an atomic number of 35, it's part of the halogen group in the periodic table.
Here are some interesting facts about bromine:

• It is a non-metal and one of the two liquid elements at room temperature.
• Bromine is known for its reddish-brown color and distinct smell.
• It's used in a variety of applications, such as agriculture and flame retardants.

When exploring electron configurations such as \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{10} 4 s^{2} 4 p^{5}\), we find 35 electrons, marking bromine as the element being described.

Boron

Boron is an essential trace element for plants and an interesting element in the periodic table. It is represented by the symbol \(B\) and has an atomic number of 5.
Boron is placed in group 13 of the periodic table and is a metalloid, which means it has properties of both metals and non-metals.
Some notable points about boron include:

• It has a tendency to form covalent bonds.
• Boron is often found in borax, used in laundry detergents and glass manufacturing.
• Boron's electron configuration \(1 s^{2} 2 s^{2} 2 p^{1}\) reveals its total of 5 electrons.

Understanding its electron configuration helps us identify boron and predict its chemical behavior.

Rubidium

Rubidium, symbolized as \(Rb\), is a soft, silvery-white metallic element in the alkali metal group with an atomic number of 37.
It is extremely reactive and shares similarities to other alkali metals such as potassium and cesium. Some characteristics of rubidium include:

• It's highly reactive and will ignite spontaneously in air.
• Rubidium is used in research and electronics as well as a component in fireworks.
• Its electron configuration is detailed as \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 4 s^{2} 3 d^{10} 4 p^{6} 5 s^{1}\).

This configuration shows it contains 37 electrons, matching its atomic number and confirming its place in the periodic table.