4.1.1 The Structure of an Atom

In this lesson, we will explore the basic components and arrangement of an atom. We will discuss the size of atoms, the composition of the nucleusA membrane-bound organelle in eukaryotic cells that contains DNA., the distribution of electrons, and how electron arrangements can change.

Size of Atoms

Atoms are incredibly small, with an approximate radius of about 1 × 10^-10 metres. The radius of a nucleus is less than 1/10 000 of the radius of an atom, and most of the mass of an atom is concentrated in the nucleus.

Composition of an Atom:

• Nucleus: At the centre of an atom, there is a positively charged nucleus composed of protons and neutrons. Protons carry a positive charge, while neutrons are neutral.
• Electrons: Surrounding the nucleus are negatively charged electrons.

Electron Arrangement

Electrons are arranged at various distances from the nucleus, occupying different energy levels or shells. They carry a negative charge, balancing the positive charge of the protons in the nucleus.

The electron arrangement can change through the absorption or emission of electromagnetic radiation.

• Higher Energy Level: When electrons absorb electromagnetic radiation, they move to higher energy levels, moving further away from the nucleus.
• Lower Energy Level: Conversely, when electrons emit electromagnetic radiation, they transition to lower energy levels, moving closer to the nucleus.

Conclusion

We explored the structure of an atom. Atoms consist of a positively charged nucleus composed of protons and neutrons, surrounded by negatively charged electrons. The nucleus is much smaller than the atom itself and contains most of the atom's mass. Electrons are arranged at various distances from the nucleus in different energy levels, and their arrangements can change through the absorption or emission of electromagnetic radiation.