Unit 4 3 orbital filling diagrams
- 2. Purpose • In the previous lesson we learned that the electrons are arranged in sublevels within an atom. We can further separate electrons within a sublevel into different orbitals. In this lesson, we will learn about orbitals and how to assign electrons to them.
- 3. Orbital Definition • An orbital is the region in space where you are most likely to find an electron. • Each orbital can hold up to two electrons • Misconception Alert: – An orbital is not an orbit. Electrons do not orbit a nucleus like planets orbit the sun on a fixed path. Rather, an orbital simply defines the space where you are most likely to find the electron.
- 4. Orbital Shapes • Orbitals can take different shapes depending on the type of sublevel they belong to. • s-type orbital are spherical in shape: • p-type orbital are considered dumbbell shaped: • d-type orbitals can have one of the following shapes: • f-type – do not worry about their shape
- 5. s-type sublevels have a single orbital • Each s-sublevel can only hold two electrons. Since an orbital holds two electrons, every s sublevel has only one orbital. • Electrons in an s-sublevel occupy spherically shaped orbitals. 1s 2s 3s 4s • Note: Notice that each p sublevel has similar orbitals, but as one gets higher in energy level, the orbitals get larger.
- 6. p-type sublevels have 3 orbitals to hold the 6 electrons • Each p-sublevel can only hold six electrons. Since an orbital holds two electrons, every p sublevel has three orbitals. • Electrons in a p-sublevel occupy dumbbell shaped orbitals. • Note: Notice that each p sublevel has similar orbitals, but as one gets higher in energy level, the orbitals get larger. 2p orbitals 3p orbitals
- 7. d-type sublevels have 5 orbitals to hold the 10 electrons • Each d-sublevel can only hold ten electrons. Since an orbital holds two electrons, every d sublevel has five orbitals. • Electrons in a d-sublevel occupy orbitals with the following shapes: – 4 of the 5 orbitals look like this: – 1 of the 5 orbitals looks like this:
- 8. f-type sublevels have 7 orbitals to hold the 14 electrons • We will not be concerned with the shapes of the f-type orbitals. Just know that each f sublevel will have 7 orbitals.
- 9. We can now break our energy level diagram down further by separating the orbitals within a sublevel • To do this one simply breaks each p sublevel into 3 pieces, each d into 5, and each f into 7 as shown on the energy diagram below. Energy 1 2 3 4 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f
- 10. To save space and put the sublevels in order, we use boxes to designate orbitals • Each box represent an orbital. The order of sublevels is the same that we learned in our previous lesson. • Note: The color was used so that it is clear which orbitals go with which sublevel. Notice how each s has a single orbital, each p has three, and the d has five. 1s 2s 2p 3s 3p 4s 3d 4p
- 11. Assigning electrons to orbitals is easy as long as you follow these rules. • When filling orbitals – Make sure you know the electron configuration first: 1s2 2s2 … – No more than two electrons can go in a box – An arrow will represent the electron – Electrons in the same box have opposite spins – this is shown with one arrow up and one arrow down. – Electrons stay unpaired within a sublevel if possible – Unpaired electrons will have the same spin
- 12. Examples • Show the orbital filling diagram of carbon. – Electron configuration: • 1s2 2s2 2p2 – Orbital filling diagram: • Note: A few things to notice – The electrons in 2p were kept separated. A third one would go in the third box. The fourth will pair up with the first. – The two unpaired electrons have arrows pointing the same way. – Even though the third orbital in 2p does not have an electron, we still show the box. 1s 2s 2p
- 13. Pause and Practice • Write the complete orbital filling diagram for O. • Write the orbital filling diagram for just the 3d electrons in Fe. • Write the orbital filling diagram for just the 5p electrons in Br.
- 14. Pause and Practice Answers • Write the complete orbital filling diagram for O. • Write the orbital filling diagram for just the 3d electrons in Fe. 3d • Write the orbital filling diagram for just the 5p electrons in Br. 5p 1s 2s 2p