Electron ConfigurationElectron Configuration

Electron ConfigurationElectron Configuration

In atomic physics and quantum chemistry, In atomic physics and quantum chemistry, electron configurationelectron configuration is the is the arrangement of arrangement of electronselectrons of an atom. of an atom.

Electron ShellsElectron Shells

Electron configuration was first conceived Electron configuration was first conceived of under the of under the Bohr modelBohr model of the atom. of the atom.

What does Bohr’s model look like?What does Bohr’s model look like?

8P8N

Valence ElectronsValence Electrons

How many electrons are in the valence How many electrons are in the valence shell of this atom?shell of this atom?

What is the “magic number”?What is the “magic number”? 88

Element GroupsElement Groups Let’s take a look at the different Groups on the Periodic Let’s take a look at the different Groups on the Periodic

Table.Table. Each Each GroupGroup has a specific number of electrons in its outer has a specific number of electrons in its outer

shell (we won’t look at the transition metals, as they are a bit shell (we won’t look at the transition metals, as they are a bit more complicated).more complicated).

Do you remember the names of each of the Periodic Table Do you remember the names of each of the Periodic Table Groups?Groups?

Group 1 = Group 1 = Alkali MetalsAlkali Metals Group 2 = Alkaline Earth MetalsGroup 2 = Alkaline Earth Metals Group 3-12 = Group 3-12 = Transition MetalsTransition Metals Group 13 = Boron FamilyGroup 13 = Boron Family Group 14 = Group 14 = Carbon FamilyCarbon Family Group 15 = Nitrogen FamilyGroup 15 = Nitrogen Family Group 16 = Oxygen FamilyGroup 16 = Oxygen Family Group 17 = Group 17 = Halogen FamilyHalogen Family Group 18 = Noble GasesGroup 18 = Noble Gases

Group 1 – Alkali MetalsGroup 1 – Alkali Metals

This Group of elements has This Group of elements has 11 electron electron in its outer shell.in its outer shell. How can we remember this?How can we remember this?

Is it going to want to gain or lose an Is it going to want to gain or lose an electron to be stable?electron to be stable? Each will choose to Each will choose to loselose an electron an electron

becoming a positive ion.becoming a positive ion.

1H

3Li

11Na

19K

37Rb

55Cs

87 Fr

Group 2 – Alkaline Earth MetalsGroup 2 – Alkaline Earth Metals

This Group of elements has This Group of elements has 22 electrons electrons in its outer shell.in its outer shell. How can we remember this?How can we remember this?

Will they gain or lose electrons and Will they gain or lose electrons and how many?how many? They will They will lose 2lose 2 electrons to become electrons to become

positive ions.positive ions.

4Be

12Mg

20Ca

38Sr

56Ba

88Ra

Group 13 – Boron FamilyGroup 13 – Boron Family

The Boron Group has The Boron Group has 33 electrons in the electrons in the outer shell.outer shell. How can we remember this?How can we remember this? Are you starting to see a pattern?Are you starting to see a pattern?

What will the elements choose to do What will the elements choose to do about attaining their 8 valence electrons?about attaining their 8 valence electrons? The elements of this Group will choose again The elements of this Group will choose again

to to lose 3lose 3 electrons becoming positive ions. electrons becoming positive ions.

5B

13Al

31Ga

49In

81Tl

Group 14 – Carbon FamilyGroup 14 – Carbon Family How many electrons does this Group How many electrons does this Group

have in its outer shell?have in its outer shell? 44

What will each choose to do with those What will each choose to do with those electrons?electrons? Since there are 4 electrons, half of 8, in the Since there are 4 electrons, half of 8, in the

outer shell, this Group is more flexible in its outer shell, this Group is more flexible in its gaining and losing. gaining and losing.

The atoms will The atoms will gain or losegain or lose electrons as electrons as needed to form compounds.needed to form compounds.

This is the This is the onlyonly Group that will do this to Group that will do this to become either cations or anions.become either cations or anions.

6

C

14Si

32Ge

50Sn

82Pb

114Uuq

Group 15 – Nitrogen FamilyGroup 15 – Nitrogen Family

How many electrons are in the outer shell How many electrons are in the outer shell of each of these atoms?of each of these atoms? 55

How do you think the atoms of this Family How do you think the atoms of this Family will attain their stable configuration of will attain their stable configuration of valence electrons?valence electrons? This group will This group will gain 3gain 3 electrons to become electrons to become

negative ions.negative ions.

7N

15P

33As

51Sb

83Bi

115Uup

Group 16 – Oxygen FamilyGroup 16 – Oxygen Family

The atoms of this Group have how many The atoms of this Group have how many electrons in the outer shell?electrons in the outer shell? 66

Describe what the elements of this Group Describe what the elements of this Group will do to attain their stable valence will do to attain their stable valence electron configuration?electron configuration? The atoms will The atoms will gain 2gain 2 electrons to become electrons to become

negative ions.negative ions.

8O

16S

34Se

52Te

84Po

116Uuh

Group 17 – Halogen FamilyGroup 17 – Halogen Family Tell me how many electrons the atoms Tell me how many electrons the atoms

from this Group have in the outer shell?from this Group have in the outer shell? 77

What will the atoms of this Group do to What will the atoms of this Group do to attain the stable valence electron attain the stable valence electron configuration?configuration? The atoms from this Group will again choose The atoms from this Group will again choose

to to gaingain electrons. electrons. How many will they gain?How many will they gain?

• 11

9F

17Cl

35Br

53I

85At

(117)(Uus)

Group 18 – Noble GasesGroup 18 – Noble Gases

How many electrons are in the outer shell How many electrons are in the outer shell of this Group’s atoms?of this Group’s atoms? 88

Will this Group gain or lose electrons?Will this Group gain or lose electrons? NeitherNeither, this Group’s valence electron , this Group’s valence electron

configuration is stable; and, the elements do configuration is stable; and, the elements do not react to form compounds as a result.not react to form compounds as a result.

2He

10Ne

18Ar

36Kr

54Xe

86Rn

118Uuo

Let’s PracticeLet’s Practice

What element does this Bohr model What element does this Bohr model represent?represent? OxygenOxygen

8P8N

More Practice…More Practice…

What element does this Bohr model What element does this Bohr model represent?represent? ChlorineChlorine

17P18N

More Practice…More Practice…

What element does this Bohr model What element does this Bohr model represent?represent? MagnesiumMagnesium

12P12N

Electron Shell Configuration…Electron Shell Configuration… Each shell has a Each shell has a set set

number of electrons.number of electrons. For those atoms that For those atoms that

have electrons in the have electrons in the 33rdrd or higher shells: or higher shells: the the nextnext to the last to the last shell needs to have 8 shell needs to have 8 in it if the atom is in it if the atom is going to going to loselose the the electrons in its outer electrons in its outer shell (there are a few shell (there are a few exceptions to this exceptions to this rule).rule).

ShellShell Max # e-Max # e-

11stst 22

22ndnd 88

33rdrd 1818

44thth 3232