The Structure of an Atom

Core Concepts:

What is an atom? In this tutorial on atomic structure, you will learn about the different parts of the atom, along with the subatomic particles found in each region. You will also learn about the properties that can be found through the subatomic particles. These properties include atomic number, atomic mass, and net charge. You will also learn what is an electron, what is a proton, and what is a neutron.

Covered in other articles:

What is an atom?

So what is the definition of an atom? An atom is a building block of matter, used to determine the characteristics of an element. Atoms are able to interact with each other through bonding, to form more complex substances, also known as molecules. These interactions determine the state of matter the atoms are in, as they can be found as solids, liquids, or gases.

What are the parts of an atom?

Atoms are made up of 3 basic components known as subatomic particles, consisting of protons (positively charged), neutrons (no charge), and electrons (negatively charged). These are the parts of the atom.

The atomic structure of these building blocks is very interesting. The protons and neutrons are located in the center of the atom, while the electrons are quite far from the center. Let’s look at these atomic particles in more detail.

Important concepts:

  • Atoms consist of very small particles called protons, neutrons, and electrons – the parts of the atom.
  • Protons and neutrons are in the center of the atom, and they make up the nucleus.
  • Protons have a positive charge.
  • Neutrons have a neutral charge (no charge).
  • Electrons have a negative charge, and are far away from the nucleus.
  • The charge on the proton and electron are exactly the same in magnitude, but opposite in sign.
  • Protons and electrons attract each other, because they have opposite charges.

What are protons?

Protons are positively charged subatomic particles, found in the nucleus of all atoms. The charge of a proton is +1. The atomic number of an element is equal to the number of protons in the nucleus. Protons consist of two up quarks, and one down quark. It has a mass of 1.007277 amu (atomic mass units).

What are neutrons?

So what is a neutron? A neutron is a neutrally charged subatomic particle, found in the nucleus of all atoms except hydrogen. A neutron has a mass of slightly more than a proton.

A neutron is a type of hadron that consists of one up quark, and two down quarks. It has a mass of 1.008665 amu (atomic mass units). In beta decay, a neutron can transform into a proton, an electron, and an antineutrino. Protons and neutrons are both called nucleons.

Neutrons are important because they determine the isotope of an element. For example, a carbon with 6 neutrons is carbon-12, but add two more neutrons and you get carbon-14, whose presence in organic material is used in radiocarbon dating, aka carbon-14 dating.

What are electrons?

Electrons are the subatomic particles that orbit the nucleus of an atom. They are negative in charge and are much smaller than protons or neutron. In fact, they are 1,800 times smaller. They also carry electricity. The charge of an electron is -1. An electron carries a charge of 1.6 x 10-19 coulombs. They have no known components or substructure. They have a mass of .000549 amu.

What is the Nucleus

Let’s talk more about atomic structure. The center of an atom is called the nucleus and is made up of both protons and neutrons. This part of the atom is able to determine a wide range of properties, such as the atomic number and atomic mass.

The atomic number of an element is found through the number of protons present in the nucleus. Example: carbon has 6 protons in its nucleus, making it also the sixth element in the periodic table.

How to find the Atomic Mass

The easiest way to find the atomic mass of an element, is to look on the periodic table. The atomic mass can also be calculated by adding the number of neutrons and protons. This is due to electrons having a really small mass, therefore not significantly contributing to the atomic mass. Example: An oxygen atom containing 8 protons and 8 neutrons, has an atomic mass of 16 amu (protons and neutrons have a mass of approximately 1 amu). You can also calculate the average atomic mass, known as the atomic weight, if you know the abundance of each isotope.

You can learn about how the nucleus was discovered.

What are Electron Shells

The electron shells are located on the outermost region of an atom surrounding the nucleus. This region contains only electrons and is able to determine the net charge of an atom.

The net charge of an atom is determined by the difference in the total number of electrons and protons. If an atom contains more protons than electrons, the net charge is positive and vice versa. Example: An atom containing 5 protons and 3 electrons, has a +2 net charge.

what is an electron? proton, neutron? learn the struture of an atom


Protons: Positively charged subatomic particles that reside in the nucleus.

Neutrons: Neutrally charged subatomic particles that reside in the nucleus.

Electrons: Negatively charged subatomic particles found in the electron shells surrounding the nucleus.

Nucleus: The region located in the center of an atom, containing both protons and neutrons.

Electron Shells: The region located on the outermost area of the atom only containing electrons.

Atomic Structure: How protons, neutrons, and electrons are arranged in an atom

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