Uploaded August 2025 | Updated September 2026, 2 weeks ago
Overview of the Main Components of an Atom
Dr. DeBacco
Main Components of an Atom
Protons
Neutrons
Electrons
The Proton
A proton is a subatomic particle found in the nucleus of an atom.
Charge: Protons carry a positive electric charge, equal in magnitude but opposite to the negative charge of an electron
Mass: A proton has a mass of about 1.6726 × 10⁻²⁷ kg, roughly 1,836 times the mass of an electron but slightly less than that of a neutron.
Location: Protons reside in the atomic nucleus, surrounded by a cloud of electrons orbiting at a distance.
Proton Composition
Composition: Protons are not fundamental particles but are made up of smaller fundamental particles called quarks.
Specifically, a proton consists of two up quarks held together by the strong nuclear force mediated by gluons.
The two quarks each with a charge of +2/3 and one down quark with a charge of -1/3.
This gives the proton its net positive charge (+1).
Role of The Proton
Role in the Atom: Protons, along with neutrons, form the nucleus of an atom.
The number of protons in an atom’s nucleus determines the atomic number, which defines the element
1 proton = hydrogen
6 protons = carbon
The Electron
An electron is a subatomic particle that orbits the nucleus of an atom.
Charge: Electrons carry a negative electric charge, equal in magnitude but opposite to the positive charge of a proton.
Mass: An electron has a mass of about 9.109 × 10⁻³¹ kg, approximately 1/1,836 the mass of a proton or neutron, making it extremely light.
Location: Electrons exist in orbitals outside the nucleus, at varying energy levels.
Electron Composition
Composition: Electrons are considered fundamental particles, meaning they are not made up of smaller constituents
Role of the Electron
Role in the Atom: Electrons occupy regions around the nucleus called orbitals, forming an electron cloud.
The number and arrangement of electrons determine an atom’s chemical properties, such as its reactivity and bonding behavior.
The Neutron
A neutron is a subatomic particle found in the nucleus of an atom.
Charge: Neutrons are electrically neutral, carrying no electric charge (0 elementary charge).
Mass: A neutron has a mass slightly greater than that of a proton but much greater than an electron’s mass (approximately 1,839 times heavier).
Location: Neutrons reside in the atomic nucleus, alongside protons, at the core of the atom.
Neutron Composition
Composition: Neutrons are not fundamental particles but are composite, made up of smaller fundamental particles called quarks.
Specifically, a neutron consists of one up quark and two down quarks held together by the strong nuclear force mediated by gluons.
One Up quark with a charge of +2/3), and two down quarks each with a charge of -1/3)
The charges of the quarks cancel out, resulting in the neutron’s neutrality.
Role of the Neutron
Role in the Atom: Neutrons, along with protons, form the nucleus of an atom.
The number of neutrons determines the isotope of an element
Ex. carbon-12 has 6 neutrons, carbon-14 has 8
Neutrons contribute to the nucleus’s mass and stability, helping to counterbalance the repulsive electromagnetic forces between positively charged protons.
Quarks- Combine to Form Protons and Neutrons
A quark is a fundamental subatomic particle that forms the building blocks of protons, neutrons, and other particles.
Quarks- Charge and Mass
Charge: Quarks carry fractional electric charges, either +2/3 or -1/3 of the elementary charge (approximately 1.602 × 10⁻¹⁹ coulombs).
Up quark: +2/3 charge
Down quark: -1/3 charge
Other types (charm, strange, top, bottom) also have fractional charges.
Mass: Quarks have extremely small masses, but their exact masses are complex to define due to quantum effects.
Quarks Composition
Composition: Quarks are fundamental particles in the Standard Model of particle physics, meaning they are not made of smaller constituents.
They combine to form composite particles like…
Protons (two up quarks, one down quark)
Neutrons (one up quark, two down quarks)
Role of the Quarks
Role in the Atom: Quarks are not directly found in atoms but are the constituents of protons and neutrons, which form the atomic nucleus.
Leptons
A lepton is a fundamental subatomic particle belonging to a family distinct from quarks.
Location: Electrons exist in orbitals around the atomic nucleus.
Other leptons, like muons, taus, and neutrinos, are typically produced in high-energy processes (ex. cosmic rays, particle accelerators, or nuclear reactions) and are not part of stable atoms.
Link to Lecture Slides: drive.google.com/file/d/16U_qxTVaQs1QUWWNzrvvHghXj57bQDl3/view?usp=drive_link
*Due to the description character limit the full work cited for "Overview of the Main Components of an Atom" can be viewed at... docs.google.com/document/d/1WzSw2gX8MVf5r-OF3MvwqaGEQxK8xlu_/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
Overview of the Main Components of an Atom
Dr. DeBacco
Main Components of an Atom
Protons
Neutrons
Electrons
The Proton
A proton is a subatomic particle found in the nucleus of an atom.
Charge: Protons carry a positive electric charge, equal in magnitude but opposite to the negative charge of an electron
Mass: A proton has a mass of about 1.6726 × 10⁻²⁷ kg, roughly 1,836 times the mass of an electron but slightly less than that of a neutron.
Location: Protons reside in the atomic nucleus, surrounded by a cloud of electrons orbiting at a distance.
Proton Composition
Composition: Protons are not fundamental particles but are made up of smaller fundamental particles called quarks.
Specifically, a proton consists of two up quarks held together by the strong nuclear force mediated by gluons.
The two quarks each with a charge of +2/3 and one down quark with a charge of -1/3.
This gives the proton its net positive charge (+1).
Role of The Proton
Role in the Atom: Protons, along with neutrons, form the nucleus of an atom.
The number of protons in an atom’s nucleus determines the atomic number, which defines the element
1 proton = hydrogen
6 protons = carbon
The Electron
An electron is a subatomic particle that orbits the nucleus of an atom.
Charge: Electrons carry a negative electric charge, equal in magnitude but opposite to the positive charge of a proton.
Mass: An electron has a mass of about 9.109 × 10⁻³¹ kg, approximately 1/1,836 the mass of a proton or neutron, making it extremely light.
Location: Electrons exist in orbitals outside the nucleus, at varying energy levels.
Electron Composition
Composition: Electrons are considered fundamental particles, meaning they are not made up of smaller constituents
Role of the Electron
Role in the Atom: Electrons occupy regions around the nucleus called orbitals, forming an electron cloud.
The number and arrangement of electrons determine an atom’s chemical properties, such as its reactivity and bonding behavior.
The Neutron
A neutron is a subatomic particle found in the nucleus of an atom.
Charge: Neutrons are electrically neutral, carrying no electric charge (0 elementary charge).
Mass: A neutron has a mass slightly greater than that of a proton but much greater than an electron’s mass (approximately 1,839 times heavier).
Location: Neutrons reside in the atomic nucleus, alongside protons, at the core of the atom.
Neutron Composition
Composition: Neutrons are not fundamental particles but are composite, made up of smaller fundamental particles called quarks.
Specifically, a neutron consists of one up quark and two down quarks held together by the strong nuclear force mediated by gluons.
One Up quark with a charge of +2/3), and two down quarks each with a charge of -1/3)
The charges of the quarks cancel out, resulting in the neutron’s neutrality.
Role of the Neutron
Role in the Atom: Neutrons, along with protons, form the nucleus of an atom.
The number of neutrons determines the isotope of an element
Ex. carbon-12 has 6 neutrons, carbon-14 has 8
Neutrons contribute to the nucleus’s mass and stability, helping to counterbalance the repulsive electromagnetic forces between positively charged protons.
Quarks- Combine to Form Protons and Neutrons
A quark is a fundamental subatomic particle that forms the building blocks of protons, neutrons, and other particles.
Quarks- Charge and Mass
Charge: Quarks carry fractional electric charges, either +2/3 or -1/3 of the elementary charge (approximately 1.602 × 10⁻¹⁹ coulombs).
Up quark: +2/3 charge
Down quark: -1/3 charge
Other types (charm, strange, top, bottom) also have fractional charges.
Mass: Quarks have extremely small masses, but their exact masses are complex to define due to quantum effects.
Quarks Composition
Composition: Quarks are fundamental particles in the Standard Model of particle physics, meaning they are not made of smaller constituents.
They combine to form composite particles like…
Protons (two up quarks, one down quark)
Neutrons (one up quark, two down quarks)
Role of the Quarks
Role in the Atom: Quarks are not directly found in atoms but are the constituents of protons and neutrons, which form the atomic nucleus.
Leptons
A lepton is a fundamental subatomic particle belonging to a family distinct from quarks.
Location: Electrons exist in orbitals around the atomic nucleus.
Other leptons, like muons, taus, and neutrinos, are typically produced in high-energy processes (ex. cosmic rays, particle accelerators, or nuclear reactions) and are not part of stable atoms.
Link to Lecture Slides: drive.google.com/file/d/16U_qxTVaQs1QUWWNzrvvHghXj57bQDl3/view?usp=drive_link
*Due to the description character limit the full work cited for "Overview of the Main Components of an Atom" can be viewed at... docs.google.com/document/d/1WzSw2gX8MVf5r-OF3MvwqaGEQxK8xlu_/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
