Chapter 5: Electrons in Atoms Electron Arrangement in Atoms

Learning Target You will determine You will determine the electron configuration and orbital notation for atoms and ions.

Electron Configuration The atomic number tells us the number of electrons in an atom. The electrons fill each energy level, sublevel and orbital like an ice tray. Once a sublevel is filled, the next energy level and sublevel are filled and so on. You will determine the electron configuration and orbital notation for atoms and ions. Principal Energy Level Number of sublevels Type of sublevelMaximum number of electrons n = 111s (1 orbital)2 n = 222s (1 orbital), 2p (3 orbitals) 8 n = 333s (1 orbital), 3p (3 orbitals), 3d (5 orbitals) 18 n = 444s (1 orbital), 4p (3 orbitals), 4d (5 orbitals), 4f (7 orbitals) 32

Draw this on the back of your periodic table You will determine the electron configuration and orbital notation for atoms and ions.

s sublevel note on periodic table You will determine the electron configuration and orbital notation for atoms and ions.

p sublevel note on periodic table You will determine the electron configuration and orbital notation for atoms and ions.

d sublevel note on periodic table You will determine the electron configuration and orbital notation for atoms and ions.

f sublevel note on periodic table You will determine the electron configuration and orbital notation for atoms and ions.

Energy Levels note on periodic table You will determine the electron configuration and orbital notation for atoms and ions.

Energy Levels and Orbitals You will determine the electron configuration and orbital notation for atoms and ions.

Electron Configuration Let’s write electron configurations for the following atoms: 1. hydrogen 2. nitrogen 3. aluminum Answers: 1. hydrogen – 1s 1 2. nitrogen – 1s 2 2s 2 2p 3 3. Aluminum - 1s 2 2s 2 2p 6 3s 2 3p 1 You will determine the electron configuration and orbital notation for atoms and ions.

Electron Configuration Let’s write electron configurations for the following atoms (cont.): 1. helium 2. oxygen 3. silicon Answers: 1. helium - 1s 2 2. oxygen - 1s 2 2s 2 2p 4 3. silicon - 1s 2 2s 2 2p 6 3s 2 3p 2 You will determine the electron configuration and orbital notation for atoms and ions.

Try some on your own Write the electron configuration for the following atoms: sodiumphosphoruspotassium You will determine the electron configuration and orbital notation for atoms and ions.

Answers Write the electron configuration for the following atoms: sodium – 1s 2 2s 2 2p 6 3s 1 phosphorus - 1s 2 2s 2 2p 6 3s 2 3p 3 potassium - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 You will determine the electron configuration and orbital notation for atoms and ions.

Orbital Notation Orbital notation is a way of drawing electron configurations. A box or blank indicates the space for an orbital. Remember an orbital can hold two electrons. An orbital will correspond to each energy level and sublevel in the configuration # Orbitals Max # e- s12 p36 d510 f714 You will determine the electron configuration and orbital notation for atoms and ions.

Orbital Notation The last property of orbitals to talk about is electron spin. Spin is represented with an arrow: ↑ or ↓ Two electrons must have opposite spins to occupy the same orbital (Pauli exclusion principle) You will determine the electron configuration and orbital notation for atoms and ions.

Examples of orbital notations You will determine the electron configuration and orbital notation for atoms and ions.

Orbital Notation Look at these examples of orbital notations. Let’s go through how they got these: hydrogen nitrogenhelium You will determine the electron configuration and orbital notation for atoms and ions.

Try some on your own Write the orbital notation for the following atoms: sulfursiliconmagnesium You will determine the electron configuration and orbital notation for atoms and ions.

Electron Configuration Electron Configuration and Orbital Notation change for elements after the first 20. This is because instead of going in order of each energy level and sublevel, we jump from the 4s to 3d An example of an electron configuration with this: Se - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 4 Notice the jump from 4s to 3d then back to 4p You will determine the electron configuration and orbital notation for atoms and ions.

Electron Configuration Let’s try some examples together. Give the electron configuration for gallium (Ga), bromine (Br) and hafnium (Hf). Ga – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 1 Br - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Hf - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 2 You will determine the electron configuration and orbital notation for atoms and ions.

Try these on your own Give the electron configurations for the following elements: –tin (Sn) –lead (Pb) –polonium (Po) –iodine (I) You will determine the electron configuration and orbital notation for atoms and ions.

Answers Give the electron configurations for the following elements: tin (Sn) - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 2 lead (Pb) - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 2 pollonium (Po) – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 4 iodine (I) - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 5 You will determine the electron configuration and orbital notation for atoms and ions.

Orbital Notations Give the orbital notations for the following elements: tin (Sn) lead (Pb) pollonium (Po) iodine (I) You will determine the electron configuration and orbital notation for atoms and ions.

Noble Gas Shortcut Notice the noble gases fill energy levels entirely, filling all the valence electrons. –This is why there is little to no reactivity with other atoms. Since the energy level is filled entirely we can use a noble gas shortcut when writing electron configurations. You will determine the electron configuration and orbital notation for atoms and ions.

Noble Gas Shortcut An example of this (Gallium): full: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 1 noble gas short cut: [Ar] 4s 2 3d 10 4p 1 noble gas short cut: [Ar] 4s 2 3d 10 4p 1 The noble gas that precedes the element is the noble gas used in the shortcut. Its electron configuration is replaced with the noble gas in brackets. Then the remaining electron configuration is written after. You will determine the electron configuration and orbital notation for atoms and ions.

Examples: Write the electron configuration using the noble gas shortcut for bromine (Br), tin (Sn), Pollonium (Po), and fluorine (F). Br: [Ar]4s 2 3d 10 4p 5 Sn: [Kr]5s 2 4d 10 5p 2 Po: [Xe]6s 2 4f 14 5d 10 6p 4 F: [He]2s 2 2p 5 You will determine the electron configuration and orbital notation for atoms and ions.

Try on your own Write the electron configuration using the noble gas shortcut for silicon (Si), lead (Pb), Iodine (I) and cesium (Cs). Si: [Ne]3s 2 3p 2 Pb: [Xe]6s 2 4f 14 5d 10 6p 2 I: [Kr]5s 2 4d 10 5p 5 Cs: [Xe]6s 1 You will determine the electron configuration and orbital notation for atoms and ions.

Isoelectronic Ions Ions can have same electronic configurations as other elements and ions. When this happens ions and/or elements are "isoelectronic" with one another. s/chemical-bond/isoelectronic.html s/chemical-bond/isoelectronic.html You will determine the electron configuration and orbital notation for atoms and ions.

Practice/Try on your own 1. Write the electron configuration for the magnesium ion. 2. Write the electron configuration for the phosphorus ion. Write the electron configuration for neon. Name one positive ion and one negative ion with the same configuration. You will determine the electron configuration and orbital notation for atoms and ions.