Question

A neutral atom of a certain element has 34 electrons. Consulting only the periodic table, identify the element and write its ground-state electron configuration.

Short answer

Element is Selenium (Se); configuration: \[ 1s^2 \,2s^2 \,2p^6 \,3s^2 \,3p^6 \,4s^2 \,3d^{10} \,4p^4 \]

Step-by-step solution

Identify the Element by its Electrons

A neutral atom has an equal number of protons and electrons. Given that the atom has 34 electrons, this implies it also has 34 protons. The element with atomic number 34 in the periodic table is Selenium (Se).

Determine the Electron Configuration

To write the ground-state electron configuration for Selenium, distribute the 34 electrons into subshells in the order dictated by energy levels following the Aufbau principle. The order is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p.1. 1s filled with 2 electrons: \[1s^2\]2. 2s filled with 2 electrons:\[2s^2\]3. 2p filled with 6 electrons:\[2p^6\]4. 3s filled with 2 electrons:\[3s^2\]5. 3p filled with 6 electrons:\[3p^6\]6. 4s filled with 2 electrons:\[4s^2\]7. 3d filled with 10 electrons:\[3d^{10}\]8. 4p filled with 4 electrons for the remaining electrons:\[4p^4\]

Write the Full Electron Configuration

Combine all the filled subshells to write the complete ground-state electron configuration for Selenium.\[ \text{Selenium (Se): } 1s^2 \,2s^2 \,2p^6 \,3s^2 \,3p^6 \,4s^2 \,3d^{10} \,4p^4 \]

Key concepts

Neutral Atom

A neutral atom is a fundamental concept in chemistry. It is defined as an atom that has no overall electric charge. This neutrality occurs because the number of protons, which are positively charged, is equal to the number of electrons, which are negatively charged. This balance cancels out any electric charge, stabilizing the atom.

In the original exercise, we were given a neutral atom with 34 electrons. Since the atom is neutral, we can determine that it also has 34 protons. This is a key aspect of identifying elements on the periodic table, as each element is defined by its number of protons, also known as its atomic number. Understanding the concept of a neutral atom helps us accurately determine characteristics like atomic number and identify elements.

Periodic Table

The periodic table is a comprehensive chart that organizes all known chemical elements in an informative way. Elements are arranged based on their atomic number, which denotes the number of protons in an atom. This organization allows for the visualization of trends and relationships between different elements.

When identifying an element using its atomic number, like in the original exercise, the periodic table helps us quickly find the specific element. In our specific case, we found Selenium by looking at atomic number 34. Each element's position not only represents its atomic number but also its properties, such as electron configuration and chemical behavior. Being familiar with the periodic table is essential for understanding atomic structure and chemical reactions.

Atomic Number

The atomic number is a unique identifier for each element on the periodic table. It tells us the number of protons in the nucleus of an atom and, for a neutral atom, also equals the number of electrons. This number is crucial because it determines the element's position on the periodic table and its chemical properties.

In the exercise provided, knowing the atomic number was essential to identifying Selenium. With 34 electrons, we understood that the atomic number was also 34, thereby pinpointing Selenium as the element in question. Understanding the atomic number allows scientists to predict an element's physical and chemical properties and behaviors, making it a central component of modern chemistry.

Aufbau Principle

The Aufbau Principle is a key guideline for determining the electron configurations of atoms. It states that electrons fill atomic orbitals in order of increasing energy levels. Generally, electrons populate lower energy levels before moving to higher ones.

In our solution, we used the Aufbau Principle to arrange the 34 electrons of Selenium into specific orbitals. This principle informs us about the specific order: starting with the 1s subshell, followed by 2s, 2p, and so on, up to 4p for Selenium's 34 electrons. This systematic process helps chemists understand an atom's structure and electron arrangements, which are crucial for predicting how it will interact with other atoms and molecules.