The vast majority of an atom's mass is hidden in its center
In short: If you could shrink down to the scale of an atom, you would find a world of extreme concentration. Almost all of an atom's weight is packed into a tiny central core, while the outer regions are nearly empty, populated by particles so light they are considered essentially weightless.
Atoms are the fundamental building blocks of all matter. While there are approximately 100 different types of atoms—ranging from the lightest, hydrogen, to the much larger uranium—they are categorized into elements when they consist of a single type of atom. When different types of atoms bond together, they form compounds. These elements are organized on the periodic table, a system constructed by Dmitri Mendeleev that groups elements with similar properties into columns.
The internal structure of an atom reveals a massive disparity in scale. At the center lies the nucleus, containing protons and neutrons. Electrons orbit this center, but they are so small that the mass of an electron is about one-thousandth the mass of a neutron or proton. Because of this significant difference, scientists treat the mass of an electron as essentially zero, meaning nearly all of an atom's mass is concentrated in the nucleus.
The identity of an atom is defined by its protons; the number of protons cannot change. In a neutral atom, this number must equal the number of electrons. However, because electrons move freely, they can be gained, lost, or shared, which drives the chemistry of the world. When an atom gains or loses electrons, it becomes an ion. Meanwhile, neutrons have no charge and do not affect chemistry, though varying numbers of neutrons in the same element create isotopes.
The stability of an atom depends on the balance of these particles. If a nucleus becomes too massive due to an excess of neutrons, it can become unstable and split, a process known as radioactivity. On the periodic table, the atomic number represents the proton count, while the atomic mass number represents the combined weight of the protons and neutrons.
Opens the Intellect+ feed with this card first. Swipe up for the next one.
Sources
- Summary by Intellect · source: What Is An Atom - Part 1 | Properties of Matter | Chemistry | FuseSchool
To cite this card, link to https://intellectplus.co.uk/app/science-what-is-an-atom-part-1-properties-of-matter-chemistry-fusesc.
How we source, check and correct cards: Editorial standards.
General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.
Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?
Related
More in Chemistry · More in Science · Latest · A–Z · All topics
