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Don't get confused between orbits and orbitals - they mean two very different things when it comes to electron theory.


An orbit is a well-defined circular path.

Electrons don't travel in orbits as shown in Bohr model.

It is used by Bohr model to describe electrons energy levels.

Each orbit is represented by an energy level.

The bigger the orbit, the higher the energy level and the electrons are more charged up and they move further away from the nucleus.

The innermost shell or orbit has the lowest energy level. The furthest orbit has the highest electron energy level.

Each orbit has a certain capacity and can hold only a certain number of electrons.

The inner shells must be filled first being going to the next level.

An atom in its lowest possible energy state (called the ground state).





An orbital is different to an orbit.

While an orbit is a path, an orbital is a region or a space.

Electrons in an atom are placed in specific energy levels (1, 2, 3, etc. denoted by the orbits mentioned above). Within each energy is a volume of space where electrons are located.

The Heisenberg Uncertainty Principle says you can't really tell where an electron is at any given time, but you can only hope to locate it in a volume of space it occupies.

  • Electrons can gain and lose energy. When they gain energy, they move further from the nucleus and occupy a different volume of space.
  • The volumes of space electrons occupy are called orbitals. Orbitals have strange shapes and they are labelled as s, p, d & f orbitals.
  • The s-orbital is a spherical shape and as the energy level gets larger, the s-orbital volume also gets larger and occupies more energy level or shells.
  • The p-orbital looks like an 8 or dumbbell shape. The p-orbital starts from energy level 2. It is not found in level 1 shell.
  • In the p-orbital, the shapes are found in the x,y,z plane so you'd get px, py and pz orbitals.
  • If they occupy the 2nd energy level, you'd get 2px, 2py and 2pz orbitals.
  • If they move up to another energy level, you'd get 3px, 3py and 3pz orbitals, and so forth.
  • Bearing in mind, electrons must fill the lower energy level first before the next. So, in electron configuration, you must feed the lower guys first before feeding the higher guys.

The strange orbital shapes (s, p, d and z) are derived from the mathematics of wave function. Electrons, as you know, are not particles, they exist as a wave and a particle at the same time. This is a hard concept to grasp if you're new to chemistry, but it's essential to get this concept right at the beginning or it can interfere with higher level learning.

  • Light also has a wave-particle dual nature and experiments have proven this.
  • They shine light through tiny double slits and when light hits the observing screen, a wave pattern is produced.
  • Likewise, they also do this experiment with electrons.
  • They shoot electrons through thin double slits and expect the electrons on the other side to show up as double lines like this || but instead, they show up as wave patterns like this | | ||| ||