Modern Atomic Model. Periodic Law When elements are arranged in order of increasing atomic number,...

Modern Atomic Modern Atomic ModelModel

Periodic LawPeriodic Law

When elements are arranged in When elements are arranged in order of increasing atomic order of increasing atomic number, the elements with number, the elements with similar properties occur at similar properties occur at periodic (regular) intervals.periodic (regular) intervals.

The periodic table is a graphical The periodic table is a graphical representation of the periodic representation of the periodic law.law.

Periodic TablePeriodic Table

Periods are the rows across – look at Periods are the rows across – look at your gold periodic table – there are 7 your gold periodic table – there are 7 periodsperiods

Groups or Families are the columns – Groups or Families are the columns – look at your gold periodic table – there look at your gold periodic table – there are 2 sets of numbers above the are 2 sets of numbers above the columns – some regular and some columns – some regular and some Roman numerals. We will use the Roman numerals. We will use the regular numbers so there are Groups 1 regular numbers so there are Groups 1 – 18.– 18.

Neils Bohr had Neils Bohr had electrons in electrons in energy levels. energy levels. His planetary His planetary model had model had electrons in electrons in orbits.orbits.

Electron orbitsElectron orbits

Electron orbitsElectron orbits Orbits are Orbits are

predictable paths. predictable paths.

Great for Great for planets but it planets but it doesn’t work doesn’t work for electrons.for electrons.

Electron orbitsElectron orbits Can’t know with any certainty Can’t know with any certainty

where an electron is or where it where an electron is or where it will be an instant later.will be an instant later.

CanCan’’t plot the path of an electron. t plot the path of an electron.

Electrons are not in Electrons are not in orbits!orbits!

The modern quantum The modern quantum mechanical model has mechanical model has electrons in energy levels that electrons in energy levels that have sublevels with have sublevels with orbitals.orbitals.

We need a new model!We need a new model!Atomic OrbitalsAtomic Orbitals

orbital - region around nucleus where an electron of particular energy is likely to be.

Orbital for a hydrogen atom Think of the places where you would find a

firefly in the dark.

It’s not really that It’s not really that hard.hard.

Get out your laminated Get out your laminated gold periodic table.gold periodic table.

Refer to it as we go Refer to it as we go through a whole bunch through a whole bunch of mind-boggling of mind-boggling slides!!!!!slides!!!!!

We are going to look at We are going to look at

the the atomic numbersatomic numbers on the table as on the table as electron electron numbersnumbers—each electron —each electron added to an atom occupies added to an atom occupies a space on the table.a space on the table.

H Periodic TableOrganization of Sublevels

He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Lr Rf Db Sg Bh Hs Mt

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb

Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No

s-block

p-block

d-block

f-block

Let’s look at the periodic table as Let’s look at the periodic table as

a a “block diagram”“block diagram” Each block is a Each block is a sublevel sublevel

within an energy levelwithin an energy level

s p d fs p d f

Sublevels have Sublevels have orbitalsorbitals

Each orbital can hold a maximum Each orbital can hold a maximum ofof

2 electrons2 electrons


He

Li Be B C N O F Ne








s-block

p-block

d-block

f-block

Go across any row in an Go across any row in an s s sublevelsublevel – how many numbers – how many numbers (electrons) across? (electrons) across?

At At 2 electrons/orbital2 electrons/orbital how how

many orbitals in an many orbitals in an s sublevels sublevel? ?

Go across any row in a Go across any row in a p p sublevelsublevel – how many numbers – how many numbers (electrons) across? (electrons) across?


many orbitals in a many orbitals in a p sublevelp sublevel? ?

Go across any row in a Go across any row in a d d sublevelsublevel – how many numbers – how many numbers (electrons) across? (electrons) across?


many orbitals in a many orbitals in a d subleveld sublevel? ?

Go across any row in an Go across any row in an f f sublevelsublevel – how many numbers – how many numbers (electrons) across? (electrons) across?


many orbitals in an many orbitals in an f sublevelf sublevel? ?

Energy Levels Have Sublevels

s sublevel

p sublevel

d sublevel

1 orbital

3 orbitals

5 orbitals

1 for an 1 for an ss sublevel, sublevel, 3 for a 3 for a pp sublevel, sublevel, 5 for a 5 for a dd sublevel and sublevel and 7 for an 7 for an ff sublevel. sublevel.

The maximum number of The maximum number of electrons in an orbital does electrons in an orbital does not vary. It is 2.not vary. It is 2.

Number of Orbitals Number of Orbitals /Sublevel/Sublevel

Atomic OrbitalsAtomic Orbitals

sublevsublevelel

orbitalorbitalss

electroelectronsns

ss 11 22pp 33 66dd 55 1010ff 77 1414

Energy level 1 has 1 sublevel 1sEnergy level 1 has 1 sublevel 1s Energy level 2 has 2 sublevels 2s, 2pEnergy level 2 has 2 sublevels 2s, 2p Energy level 3 has 3 sublevels 3s, 3p, Energy level 3 has 3 sublevels 3s, 3p,

3d3d Energy level 4 has 4 sublevels 4s, 4p, Energy level 4 has 4 sublevels 4s, 4p,

4d, 4f4d, 4fNumber of sublevels = Energy Level

Arrangement of Arrangement of Sublevels in Energy Sublevels in Energy

LevelsLevels

s sublevel has 1 orbitals sublevel has 1 orbital

s orbital: lowest energy holds 1 pair of electrons

1s

1s2s3s

p sublevel has 3 orbitalsp sublevel has 3 orbitals

p orbitals: hold 3 pairs of electrons

px

d sublevel has 5 orbitalsd sublevel has 5 orbitals

d orbitals: holds 5 pairs of electrons

f sublevel has 7 orbitalsf sublevel has 7 orbitals

f orbitals: hold 7 pairs of electrons

Orbital Gallery

2nd Energy Level

1st Energy Level

s

s

p

3rd Energy Level

s

p

d

4th Energy Level

s

p

d

f

It so happens that the 4s sublevel is at a lower energy state than the 3d sublevel.

Electrons will fill in the 4s sublevel before they go back and fill the 3d sublevel.

Electrons will fill in the sublevel with the lowest energy state first before filling in the next sublevel.

5th Energy Level

s

p

d

f


He

Li Be B C N O F Ne








s-block

p-block

d-block

f-block

Periodic TableSublevels1

3

4

5

6

7

2

1s

1s

2s

7s

6s

5s

4s

3p

3s

2p

6p

5p

4p

6d

5d

4d

3d

5f

4f

Getting Started:Getting Started: Each box represents an orbitalEach box represents an orbital

Orbitals are in groups according to Orbitals are in groups according to sublevelssublevels

Arrows represent electronsArrows represent electrons

Any single orbital can hold a maximum of Any single orbital can hold a maximum of 2 electrons2 electrons

A. General RulesA. General Rules Each orbital can hold TWO electrons with Each orbital can hold TWO electrons with

opposite spins.opposite spins.

A. General RulesA. General Rules

Electrons fill the Electrons fill the lowest energy lowest energy orbitals first.orbitals first.

““Lazy Tenant Lazy Tenant RuleRule””

RIGHTWRONG

A. General RulesA. General Rules Within a sublevel, place one eWithin a sublevel, place one e-- per orbital per orbital

before pairing them.before pairing them.

““I donI don’’t want to share my room if I dont want to share my room if I don’’t have t have to!to!””

O

8e-

Orbital DiagramOrbital Diagram

B. NotationB. Notation

1s 2s 2p

HomeworkHomework

Read pages 135 – 138Read pages 135 – 138

Do Orbital Diagrams Do Orbital Diagrams Worksheet – both sides.Worksheet – both sides.

Modern Atomic Model. Periodic Law When elements are arranged in order of increasing atomic number,...

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