Electron Configurations for the Electron Configurations for the Ions of Transition Metals & Main Ions of Transition Metals & Main Group ElementsGroup Elements

Chemistry 11Chemistry 11

The Order of Orbital “Filling”The Order of Orbital “Filling”

1.1. Lowest energy to higher energy.Lowest energy to higher energy.2.2. Adding electrons can change the energy of Adding electrons can change the energy of

the orbital.the orbital.3.3. Half filled orbitals have a lower energy.Half filled orbitals have a lower energy.4.4. Makes them more stable.Makes them more stable.5.5. Changes the filling orderChanges the filling order

PracticePractice: Writing Electron Configurations: Writing Electron Configurations

TitaniumTitanium - 22 electrons - 22 electrons

1s1s222s2s222p2p663s3s223p3p664s4s223d3d22

VanadiumVanadium - 23 electrons - 23 electrons

1s1s222s2s222p2p663s3s223p3p664s4s223d3d33

ChromiumChromium - 24 electrons - 24 electrons1s1s222s2s222p2p663s3s223p3p664s4s223d3d44 is expectedis expected

But this is But this is wrongwrong!! Why?!! Why?

True Configuration of ChromiumTrue Configuration of Chromium 1s1s222s2s222p2p663s3s223p3p664s4s113d3d55

Why?Why? This gives us two half filled orbitals.This gives us two half filled orbitals. Slightly lower in energy.Slightly lower in energy. The same principal applies to copper.The same principal applies to copper.

Copper’s Electron ConfigurationCopper’s Electron Configuration Copper has 29 electrons so we expectCopper has 29 electrons so we expect

1s1s222s2s222p2p663s3s223p3p664s4s223d3d99

But the actual configuration isBut the actual configuration is1s1s222s2s222p2p663s3s223p3p664s4s113d3d1010

This gives one filled orbital and one half filled This gives one filled orbital and one half filled orbital.orbital.

Remember these exceptionsRemember these exceptions

Valence ElectronsValence Electrons Are the electrons in the highest occupied energy level Are the electrons in the highest occupied energy level

of an element’s atom.of an element’s atom. Are usually the only electrons used in the formation of Are usually the only electrons used in the formation of

chemical bonds.chemical bonds.Note:Note:

Many of the Many of the similarsimilar chemical properties of elements chemical properties of elements in the same group (vertical column) are related to the in the same group (vertical column) are related to the numbernumber of “ of “ss” and “” and “pp” electrons in the highest occupied ” electrons in the highest occupied energy level. These electrons are energy level. These electrons are valencevalence electrons. electrons.

Example 1:Example 1: Sodium Sodium

1111Na Na

1s1s222s2s222p2p663s3s11

HighestHighest energy level = 3 energy level = 3 Single “s” electronSingle “s” electron No “p” electrons for this elementNo “p” electrons for this element Na has 1 Na has 1 valencevalence electron electron Ion: Ion:

Example 2:Example 2: Phosphorus Phosphorus

1515PP

1s1s222s2s222p2p663s3s2 2 3p3p33

HighestHighest energy level = 3 energy level = 3 Two “s” electronsTwo “s” electrons Three “p” electrons Three “p” electrons 5 5 valencevalence electrons electrons Ion: Ion:

Example 3:Example 3: Potassium Potassium

1919KK

Electron ConfigurationsElectron Configurations 1s1s222s2s222p2p663s3s2 2 3p3p6 6 4s4s11

HighestHighest energy level = 4 energy level = 4 1 1 valencevalence electron electron Ion:Ion:

Example 4:Example 4: Carbon Carbon

66CC

Electron ConfigurationElectron Configuration 1s1s222s2s222p2p22

HighestHighest energy level = 2 energy level = 2 4 4 valencevalence electrons electrons Ion: Ion:

Example 5:Example 5: Magnesium Magnesium

1212MgMg

Electron ConfigurationElectron Configuration 1s1s222s2s222p2p663s3s22

HighestHighest energy level = 3 energy level = 3 2 2 valencevalence electrons electrons Ion:Ion:

Example 6:Example 6: Oxygen Oxygen

88OO

Electron ConfigurationElectron Configuration 1s1s222s2s222p2p44

HighestHighest energy level = 2 energy level = 2 6 6 valencevalence electrons electrons Ion:Ion:

Transition MetalsTransition Metals Do not form ions with noble gas configurationsDo not form ions with noble gas configurations If they did, they would have to lose 4 or more If they did, they would have to lose 4 or more

electrons, and the energy needed to do this electrons, and the energy needed to do this would be too high.would be too high.

These metals do form cations (“+” charged ion) These metals do form cations (“+” charged ion) with more than one charge (multi-valent)with more than one charge (multi-valent)

Electrons are first moved from the outer “s” and Electrons are first moved from the outer “s” and then inner “d” sublevels.then inner “d” sublevels.

Example 1:Example 1:

2525Mn Mn ((1818Ar)4sAr)4s223d3d55

MnMn2+2+ losesloses 2 electrons from the “ 2 electrons from the “ss” ” sublevelsublevel

MnMn2+2+ ((1818Ar)4sAr)4s003d3d55

Example 2:Example 2:

2626FeFe ((1818Ar)4sAr)4s223d3d66

FeFe2+2+ losesloses 2 electrons from the “ 2 electrons from the “ss” ” sublevelsublevel

FeFe2+2+ ((1818Ar)4sAr)4s003d3d66

FeFe3+3+ ((1818Ar)4sAr)4s003d3d55

Question 1Question 1Read the following electron configurations todetermine the identities of the following elements:a) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

b) 1s2 2s2 2p6 3s2 3p3

c) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f 5d10 6p6

d) 1s2 2s2 2p2

e) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5

Question 2Question 2Explain what is meant by the term“isoelectronic”.Answer:The prefix “iso” means “the same”, soisoelectronic means that two atoms or ions havethe same number of electrons or the sameelectron configuration.

Question 3Question 3 What are four ions, with their charges, that are isoelectronic with each of the following:a) neon: N3– O2– F1– Na1+ Mg2+ Al3+ b) argon: P3– S2– Cl1– K1+ Ca2+ Sc3+

c) krypton: As3– Se2– Br1– Rb1+ Sr2+ Y3+

d) an S2– ion: P3– Cl1– K1+ Ca2+ Sc3+

Question 4Question 4A calcium ion, Ca2+ , is isoelectronic with argon. Does thismean that calcium has “turned into” argon?Explain.Answer:No, calcium has not turned into Argon. Remember, it is the atomic number (number of protons) that determines what typeof element an atom is. The calcium ion has the same numberof electrons as an Argon atom. This just means that they are Both stable octet with 18 electrons.

Question 5Question 5

Write the electron configuration for the element with atomic number 117. In whichchemical group does it belong? Predict thecharge on the ion that it will form.

Question 5Question 51s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2

4f14 5d10 6p6 7s2 5f14 6d10 7p5

This element belongs to the Halogen family or Group 17 (VIIB). It will gain one electron to havethe same configuration as a Noble Gas, so it willform ions with a charge of 1-.