Question

Give the symbol of the atom with the following orbital diagram. \(2 \mathrm{~s}\) 1 \(2 \mathrm{p}\) \(3 \mathrm{~s}\) 1 \(-\) \(3 \mathrm{p}\) \((\uparrow \downarrow)(\quad)(\quad)(\quad)\) (b) \((\uparrow \downarrow)\) \((\uparrow \downarrow) \quad(\uparrow \downarrow)(\uparrow \downarrow)(\uparrow \downarrow)\) \((\uparrow \downarrow) \quad(\uparrow)(\uparrow)(\uparrow\) (c) \((\uparrow \downarrow)\) \((\uparrow \downarrow) \quad(\uparrow \downarrow)(\uparrow)(\uparrow\) ( ) 1

Short answer

Question: Identify the elements represented by the following electron orbital diagrams: (a) 2s^1 2p^3 3s^1 3p^1 (b) 1s^2 2s^2 2p^6 3d^2 3s^2 3p^4 (c) 1s^2 2s^2 2p^5 Answer: The elements represented by the given electron orbital diagrams are: (a) Carbon (C) (b) Argon (Ar) (c) Fluorine (F)

Step-by-step solution

Identify the electron configuration for each case

For each orbital diagram, count the number of electrons in each energy level and orbital type, using superscripts to indicate the number of electrons in each orbital. (a) \(2s^1 2p^3 3s^1 3p^1\) (b) \(1s^2 2s^2 2p^6 3d^2 3s^2 3p^4\) (c) \(1s^2 2s^2 2p^5\)

Find the total number of electrons for each case

Sum up the total number of electrons present in each given electron configuration. (a) \(1 + 3 + 1 + 1 = 6\) electrons (b) \(2 + 2 + 6 + 2 + 2 + 4 = 18\) electrons (c) \(2 + 2 + 5 = 9\) electrons

Identify the elements by their atomic number

Use the periodic table to find the elements with atomic numbers corresponding to the total number of electrons in each case. The atomic number is equal to the number of protons in the nucleus, which is also equal to the number of electrons in a neutral atom. (a) The element with 6 electrons is Carbon (C). (b) The element with 18 electrons is Argon (Ar). (c) The element with 9 electrons is Fluorine (F).

Report the symbols of the atoms

Now that we have identified the elements for each case, the symbols of the atoms are as follows: (a) Carbon (C) (b) Argon (Ar) (c) Fluorine (F)

Key concepts

Electron Configuration

Understanding electron configuration is fundamental in grasping how atoms behave chemically. The electron configuration of an atom describes the placement of electrons in atomic orbitals following specific rules. The most important rule to remember is the Aufbau principle, which states that electrons fill the lowest energy orbitals first. This is followed by Pauli’s exclusion principle, which tells us that an orbital can hold a maximum of two electrons with opposite spins, and Hund’s rule, which explains that electrons will occupy each orbital singly before doubling up.

To visualize electron configurations, chemists use an orbital diagram, a pictorial representation of the orbitals and the electrons in them. For instance, the notation \(2s^1 2p^3\) indicates that the second energy level's s orbital has one electron, and the p orbitals have three electrons spread out among them, according to Hund's rule. This concept is crucial when predicting an element's chemical behavior and reactivity.

Atomic Number

The atomic number is a fundamental property of an element that defines its identity. It is denoted by the symbol Z and refers to the number of protons in the nucleus of an atom. Since atoms are neutral, the atomic number is also equal to the number of electrons in an atom. For example, if an atom has an atomic number of 6, it will have six protons and, assuming it’s neutral, six electrons.

This concept is paramount when solving problems that involve identifying elements based on electron configurations. For instance, the atom with the electron configuration \(1s^2 2s^2 2p^5\) has 9 electrons, thus an atomic number of 9, which corresponds to fluorine (F). Knowing the atomic number allows us to use the periodic table to connect an electron configuration with a specific element.

Periodic Table of Elements

The periodic table is more than just a chart of elements; it's a comprehensive tool that reflects the systematic organization of the elements based on their atomic numbers, electron configurations, and recurring chemical properties. Elements are arranged in order of increasing atomic number in rows called periods and columns known as groups. These arrangements provide insight into the elements’ behaviors and relationships with each other.

The table's layout helps us locate an element and predict its properties. For example, the elements in the same group usually have similar chemical behaviors because they have similar valence electron configurations. If a student knows an atom's electron configuration, they can not only find the element on the periodic table but also predict the types of chemical reactions it may participate in. For instance, with the electron configuration of Argon (\(1s^2 2s^2 2p^6 3s^2 3p^4\)), we can determine its placement in the noble gas group, which is known for being chemically inert.