In chemistry, there are 118 known elements, also known as substances that we can’t break down by non-nuclear reactions. These elements are categorized into three main groups: metals, non-metals, and metalloids. So, which group does hydrogen belong to? Is hydrogen a metal, a non-metal, or a metalloid? If this is something you’re curious about, we’ve got you covered.
Hydrogen is a non-metal from Group 1A on the periodic table.
But why do people think that hydrogen might actually be a metal? To answer your question, this article will explain the physical and chemical properties of metals and non-metals, in general. The following sections will also discuss the properties and facts about hydrogen to make it easier for you to understand why hydrogen is considered to be a non-metal.
Physical and Chemical Properties of Metals
All metals have some common physical and chemical properties that make them easily distinguishable from non-metals. By understanding the key properties, you can easily tell if a given element is a metal or a non-metal.
The physical properties of metals include being solid at room temperature, having luster, being hard and resistant to external forces, being malleable and ductile, having high tensile strength, conducting heat and electricity, and having high density and high melting and boiling points.
In terms of chemical properties, metals have very low electronegativity, some metals react with air and corrode, metals produce metal oxides when being burnt in oxygen, soluble metals form metal hydroxides when dissolved in water, and metals react with acids to produce salts.
Be aware that these properties don’t apply to every single metal element we have in the periodic table. There are some exceptions to keep in mind.
For example, mercury is a metal but it’s liquid at room temperature. Besides, metals are hard but zinc and gallium are soft. In addition, zinc is non-malleable and non-ductile unlike other metals. While most metals have high melting points and density, sodium and potassium are the exceptions to this.
Physical and Chemical Properties of non-Metals
Just like metals, non-metals can also be characterized by certain physical and chemical properties. And these characteristics make them completely different from metals. Determining if a given element is a metal or a non-metal requires the knowledge of the properties of both types of elements.
The physical properties of non-metals are being solids, liquids, or gases at room temperature, being dull and non-lustrous, conducting heat and electricity very poorly, having no malleability of ductility and being brittle, and having lower melting and boiling points compared to metals.
When it comes to the chemical properties of non-metals, they are characterized by high electronegativity and high ionization energies, form covalent bonds when reacting with other compounds and gaining electrons, act as oxidizing agents, and react with oxygen to form non-metallic acidic oxides.
Note that there are a few exceptions to consider. For example, iodine and diamond are non-metals but they are lustrous rather than dull. Besides, diamond is also hard and ductile rather than soft and brittle. It also has higher melting and boiling points. In addition, graphite is a good conductor of heat and electricity, although it’s a non-metal.
Physical and Chemical Properties of Hydrogen
As we’ve covered the physical and chemical properties of metals and non-metals in general, let’s continue with the properties of hydrogen to determine whether it’s a metal or a non-metal.
Hydrogen is a gaseous substance, and under standard conditions, hydrogen gas is a diatomic molecule. When compared to other non-metals, hydrogen has a relatively low electronegativity of 2.2. Besides, hydrogen can either share or accept its electron when reacting with other substances. So, hydrogen can act like an alkali metal or a halogen non-metal in chemical reactions.
For more information about hydrogen and its properties, check out this video by Professor Dave Explains.
So, Is Hydrogen a Metal or a non-Metal?
The main factor that confuses students and makes it tricky to decide whether hydrogen is a metal or a non-metal is that hydrogen can act like an alkali metal or a halogen non-metal. For that reason, hydrogen is either placed above alkali metals or halogens in the periodic table. However, hydrogen is very different from both alkali metals and halogens.
Based on its physical and chemical properties, hydrogen is a non-metal that forms a diatomic molecule in a gaseous phase. Unlike other non-metals, hydrogen can produce both positively and negatively charged ions when reacting with other substances.
That being said, although hydrogen is typically placed above alkali metals in the periodic table, it’s considered to be a non-metal.
Can Hydrogen Behave as a Metal?
Under standard temperature and pressure, hydrogen is a non-metal. However, hydrogen can also change its phase from a gas to a liquid and then to a solid and show metallic behavior if the pressure is too high.
Yes, hydrogen can behave as a metal when it becomes a solid under extremely high pressure and other favorable conditions. In the solid or metallic phase, hydrogen acts as an electrical conductor.
Keep in mind that producing metallic hydrogen requires extremely high pressure, approximately 400-500 GPa.
For further information about metallic hydrogen, check out this research paper.