The key difference between hydrogen atom and hydrogen ion is that the hydrogen atom is neutral whereas the hydrogen ion carries a charge.
Hydrogen is the first and the smallest element in the periodic table and is denoted as H. It is categorized under group 1 and period 1 in the periodic table because of its electron configuration: 1s1. Hydrogen can take up an electron to form a negatively charged ion, or can easily donate the electron to produce a positively charged proton. If not, it can share the electron to make covalent bonds.
The elements in the periodic table are not stable except the noble gases. Therefore, elements try to react with other elements in order to gain the noble gas electron configuration and achieve stability. Similarly, hydrogen also has to obtain an electron to achieve the electron configuration of the noble gas, Helium. When achieving this electron configuration, it forms the hydrogen ion.
CONTENTS
1. Overview and Key Difference
2. What is a Hydrogen Atom
3. What is a Hydrogen Ion
4. Side by Side Comparison – Hydrogen Atom vs Hydrogen Ion in Tabular Form
5. Summary
What is a Hydrogen Atom?
Hydrogen atom is the first element in the periodic table. A hydrogen atom has one electron and one proton. Therefore, its electron configuration is 1s1. Moreover, it only has one electron in the s-suborbital though this orbital can accommodate two electrons. Thus, hydrogen atom is unstable and very reactive in order to obtain a stable electron configuration.
Figure 1: Structure of Hydrogen Atom
Since the number of protons and electrons in a hydrogen atom are similar, this atom does not carry a net charge. Therefore, we say it is neutral. However, there are three isotopes of hydrogen: protium-1H (no neutrons), deuterium-2H (one neutron), and tritium- 3H (two neutrons). These isotopes have varying numbers of neutrons in the atomic nucleus.
What is a Hydrogen Ion?
Hydrogen ion is the form of hydrogen element that carries a charge. The charge of this ion can be either positive or negative, depending on the way that it forms. It may form from either the removal of one electron from atomic hydrogen or from electron gaining. Therefore, hydrogen ion has either a +1 or -1 charge (monovalent). We can denote the positively charged hydrogen ion as H+ (cation) and the negative ion as H- (anion).
Figure 2: Formation of Ions from Hydrogen Atom
The cation of protium is specifically known as protons, and they are the type of hydrogen atoms we mainly consider in chemical reactions since the natural abundance of protium is very high compared to other isotopes. Further, this exists in aqueous solutions as hydronium ions (H3O+).
Hydrogen ions are responsible for acidity, and the concentration of hydrogen ions is taken to calculate pH values. When hydrogen atoms react with other nonmetals, hydrogen ions are formed, and these are released to the aqueous medium completely or partially when the molecule is dissolved. Although the formation of hydrogen anion is rare, it forms when hydrogen reacts with metals such as group 1 metals.
What is the Difference Between Hydrogen Atom and Hydrogen Ion?
Hydrogen is the smallest chemical element. It has one proton and one electron, making it neutral. However, the ions of hydrogen atom are charged species. Thus, the key difference between hydrogen atom and hydrogen ion is that the hydrogen atom is neutral whereas hydrogen ion carries a charge. Another significant difference between hydrogen atom and hydrogen ion is that hydrogen atom has one electron while cation of hydrogen has no electrons and anion of hydrogen has two electrons.
Moreover, hydrogen atom is highly reactive in order to obtain a stable electron configuration. But, hydrogen ions are less/not reactive since they have already gained the stable state. The charge of the cation is +1, and the charge of anions is -1. So, we can consider this also as a difference between hydrogen atom and hydrogen ion.
Summary – Hydrogen Atom vs Hydrogen Ion
Hydrogen is the first element in the periodic table of elements. Therefore, it is the smallest atom. It can form either positively charged or negatively charged ions. The key difference between hydrogen atom and hydrogen ion is that the hydrogen atom is neutral whereas hydrogen ion carries a charge.
Reference:
1. JOHN C. MORRISON, in Modern Physics, 2010
2. “8.1: The Hydrogen Atom.” Physics LibreTexts, Libretexts, 2 May 2019, Available here.
Image Courtesy:
1. “2750576” (CC0) via Pixabay
2. “Ions” By Jkwchui – Own work (CC BY-SA 3.0) via Commons Wikimedia