Are you having challenges when it comes to the atomic theory and atoms in general? If so, then this article is all you need to improve in this section. Through research, we have combined a cheat sheet that you can use to enhance your knowledge in atomic theory and atoms. Hence if you wish to learn more about this topic, follow along as we unravel this fantastic mystery.


Matter is composed of tiny particles known as atoms. Atoms merge to create elements. These elements consist of only one type of atom. When atoms of contrasting elements combine, they form:

  1. Objects
  2. Compounds
  3. Molecules

Key take away on the atomic model

  1. The matter’s basic building block is an atom. You cannot break an atom using chemical means, it is at its lowest level. However, atoms can be altered by nuclear reactions.
  2. Atoms consist of 3 different parts:
    • Protons (charges positively)
    • Neutrons (charged negatively)
    • Electrons (charged negatively)
  3. Neutrons and protons form the nucleus of the atoms. Protons attract electrons to the atom’s nucleus. However, due to their fast movement, they orbit the nucleus instead of sticking onto the protons.
  4. An atom’s identity is based upon the number of protons it contains, or you can simply call it the atomic number.

Atomic parts extended

As discussed above, an atom consists of 3 parts: neutrons, protons, and electrons.

Protons – protons form the atom’s basis. Even though atoms lose and gain electrons and neutrons, they are identified according to the number of protons they contain. Capital Z is the letter used to represent the “proton number.”

Neutrons – when you add neutrons and protons, you get the so-called atomic mass number of a specific atom. N is the symbol used to identify the Neutron number in a particular atom. Hence the N + Z = atomic mass. A nuclear force that is pretty strong is used to bind neutrons and protons together, thus forming the atom’s nucleus.

Electrons – They are pretty small compared to neutrons and protons. Electrons orbit around the nucleus of the atom.

Basics of atoms that are a must know

Every electron contains an electrical charge that is negative. Every proton on an atom has an electrical charge that is positive. The amount of charge in an electron matches the magnitude of the amount of charge in a proton, hence the attraction. Just like in physics, like charges repel, and opposite charges attract. Therefore, protons repel other protons, and electrons repel other electrons. The opposite is true as electrons are attracted by protons.

Every neutron is neutral electrically. What that means is that neutrons don’t contain any charge. They are hence not attracted to neutrons and protons electrically.

Neutrons and protons are almost equal in size. They are also large compared to electrons. Neutron mass essentially equals proton mass. The proton mass is about 1840 times larger than the electron mass. 

An atom’s nucleus contains neutrons and protons. Since the neutrons bear no charge, that means that the nucleus carries the proton’s positive charge; it is hence positively charged.

Atoms are small. Their average size is 100 picometers, that is, one-tenth of a billion meters – rather small, right.

An atom’s mass is mainly concentrated on its nucleus. However, electrons occupy most of its volume.


Atoms are fun and interesting to study. We hope that this article has helped you understand atoms and the atomic theory to ace that chemistry test.

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