Electron Configurations Wrap Up

The Layout of the Periodic Table Elements in the same families have very similar electron configurations. Elements in the same families have very similar electron configurations. All Alkali Metals end in s 1 All Alkali Metals end in s 1 All Alkaline Earth Metals end in s 2 All Alkaline Earth Metals end in s 2 Different chunks of the Periodic Table all have end in the same subshells Different chunks of the Periodic Table all have end in the same subshells The period number determines the highest shell that is occupied. The period number determines the highest shell that is occupied.

Lanthanum, Actinium, Lutetium, Lawrencium These don’t quite fit into our nice neat blocks These don’t quite fit into our nice neat blocks Think of Lanthanum and Actinium being in the f block Think of Lanthanum and Actinium being in the f block Think of Lutetium and Lawrencium being in the d block Think of Lutetium and Lawrencium being in the d block

Losing and Gaining Electrons Ion – an atom that has gained or lost electrons. Ion – an atom that has gained or lost electrons.

Patterns in Forming Ions Lots of atoms form ions that allow them to get close to a noble gas electron configuration. Lots of atoms form ions that allow them to get close to a noble gas electron configuration. Noble gas configurations are especially stable Noble gas configurations are especially stable Will lose or gain electrons depending on which way it is easier to go. Will lose or gain electrons depending on which way it is easier to go.

Patterns in Forming Ions Alkali Metals (Sodium) Alkali Metals (Sodium) Easiest to lose one electron Easiest to lose one electron Alkaline Earth Metals (Magnesium) Alkaline Earth Metals (Magnesium) Easiest to lose two electrons Easiest to lose two electrons Group 13 (Aluminum) Group 13 (Aluminum) Easiest to lose three electrons Easiest to lose three electrons Group 14 (Carbon) Group 14 (Carbon) Can go both ways Can go both ways Can lose four electrons or gain four electrons Can lose four electrons or gain four electrons In reality does a variety of different things and is not always predictable In reality does a variety of different things and is not always predictable

Patterns in Forming Ions Group 15 (Nitrogen) Group 15 (Nitrogen) Easiest to gain 3 electrons Easiest to gain 3 electrons Chalcogens (Oxygen) Chalcogens (Oxygen) Easiest to gain 2 electrons Easiest to gain 2 electrons Halogens (Fluorine) Halogens (Fluorine) Easiest to gain 1 electron Easiest to gain 1 electron Noble Gasses (Neon) Noble Gasses (Neon) Usually don’t react Usually don’t react

Chemistry Always has Exceptions! Some elements do not make it to a noble gas configuration. Some elements do not make it to a noble gas configuration. Ga 3+ - is actually 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 Ga 3+ - is actually 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 Gallium ions do not follow the diagonal line diagram. Gallium ions do not follow the diagonal line diagram. Pseudo-noble gas configurations – stable configurations with all occupied subshells completely filled. Pseudo-noble gas configurations – stable configurations with all occupied subshells completely filled.

Other Examples of Exceptions Copper Copper Expect 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 9 Expect 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 9 Actually 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 Actually 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 Copper gains stability with a full d-subshell Copper gains stability with a full d-subshell Chromium Chromium Expect 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4 Expect 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4 Actually 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 Actually 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 Chromium gains stability with a half-full d- subshell Chromium gains stability with a half-full d- subshell

Transition Metal Ions Gets complicated because of the d-orbitals Gets complicated because of the d-orbitals Typically form +2 ions but can have many different charges Typically form +2 ions but can have many different charges

Stable Electron Configurations Least stable configuration Least stable configuration Partially filled subshell Partially filled subshell Half filled subshell Half filled subshell Full subshell Full subshell Noble Gas Configuration Noble Gas Configuration Most Stable Configuration Most Stable Configuration

Predicting Common Ion Charges You can predict charges on ions formed from elements close to the Noble Gasses You can predict charges on ions formed from elements close to the Noble Gasses Groups 1 and 2, and the nonmetals Groups 1 and 2, and the nonmetals You are unlikely to be able to predict the charge on anything else You are unlikely to be able to predict the charge on anything else

The Octet “Rule” Most stable ions have noble gas configurations Most stable ions have noble gas configurations Xe = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 Xe = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 Usually making the most stable ion leaves 8 electrons in the outermost n shell Usually making the most stable ion leaves 8 electrons in the outermost n shell For example: 5s 2 and 5p 6 For example: 5s 2 and 5p 6 Valence electrons - the number of electrons in the outermost n shell Valence electrons - the number of electrons in the outermost n shell Core electrons – non-valence electrons Core electrons – non-valence electrons All d and f electrons are core electrons. Why? All d and f electrons are core electrons. Why?

Valence Electrons How many valence electrons does each family have? How many valence electrons does each family have? Group 1 (Alkali Metals) have 1 valence electron Group 1 (Alkali Metals) have 1 valence electron Group 2 (Alkaline Earth Metals) have 2 valence electrons. Group 2 (Alkaline Earth Metals) have 2 valence electrons. Transition Metals and F-Blocks have 2 valence electrons. Transition Metals and F-Blocks have 2 valence electrons. Group 13 has 3 valence electrons Group 13 has 3 valence electrons Group 14 has 4 valence electrons Group 14 has 4 valence electrons Group 15 has 5 valence electrons Group 15 has 5 valence electrons Group 16 (Chalcogens) has 6 valence electrons Group 16 (Chalcogens) has 6 valence electrons Group 17 (Halogens) has 7 valence electrons Group 17 (Halogens) has 7 valence electrons Group 18 (Noble Gases) has 8 valence electrons Group 18 (Noble Gases) has 8 valence electrons

Even More Shorthand Based on the stability of the noble gas configurations Based on the stability of the noble gas configurations Noble gas becomes the “core” of the configuration. Noble gas becomes the “core” of the configuration. Leave the outermost electrons alone because this is where the reactions happen. Leave the outermost electrons alone because this is where the reactions happen.

Condensed Electron Configurations For silicon the electron configuration is normally written 1s 2 2s 2 2p 6 3s 2 3p 2 For silicon the electron configuration is normally written 1s 2 2s 2 2p 6 3s 2 3p 2 Find the previous noble gas Find the previous noble gas Put it in brackets in place of the electron configuration of the noble gas. Put it in brackets in place of the electron configuration of the noble gas. For silicon the previous noble gas is Neon. For silicon the previous noble gas is Neon. Neon’s configurations is 1s 2 2s 2 2p 6 Neon’s configurations is 1s 2 2s 2 2p 6 Silicon = [Ne] 3s 2 3p 2 Silicon = [Ne] 3s 2 3p 2

Condensed Electron Configurations Antimony, Sb Antimony, Sb Mercury, Hg Mercury, Hg Fermium, Fm Fermium, Fm Darmstadium, Ds, #110 Darmstadium, Ds, #110

MORE Shorthand? AAAHHH! Lewis Dot Diagrams – using dots to represent the valence electrons of an atom. Lewis Dot Diagrams – using dots to represent the valence electrons of an atom. Write the symbol of the element in the middle. Write the symbol of the element in the middle. Draw dots to represent the valence electrons only. Draw dots to represent the valence electrons only. One side is used to represent the valence s orbital. One side is used to represent the valence s orbital. Other three sides are used for valence p orbitals. Other three sides are used for valence p orbitals. Must use Hund’s Rule for placing the electrons in p orbitals. Must use Hund’s Rule for placing the electrons in p orbitals.

Lewis Dot Diagrams Practice Potassium Potassium Calcium Calcium Chromium Chromium Gallium Gallium

Lewis Dot Diagram Practice Germanium Germanium Arsenic Arsenic Selenium Selenium Bromine Bromine Krypton Krypton