1869 DMITRI MENDELEEV - PowerPoint Presentation

Slide1

1869 DMITRI MENDELEEVArranged the elements by increasing atomic mass, and noticed properties repeat regularlyLeft a space if an element didn’t belong in a particular column

THE PERIODIC TABLE

1H-1 (of

14)Slide2

Mendeleev stated the PERIODIC LAW

:The properties of the chemical elements are not arbitrary, but vary with their atomic masses in a systematic wayMendeleev was able to predict properties of undiscovered elements

However, accurate atomic mass determinations showed errors in the table

1H-2 (of

14)

THE PERIODIC TABLESlide3

1912 HENRY MOSELEYMeasured the frequency of x-rays from excited atoms Found they were proportional to the ATOMIC NUMBER of the atoms, not the atomic mass

1H-3 (of

14)Slide4

1912 HENRY MOSELEYThis work changed the PERIODIC LAW:The properties of the chemical elements vary with atomic number

1H-4 (of

14)Slide5

PERIOD or SERIES – A row

GROUP or FAMILY – A column

Elements in columns have similar properties because they have the same number of valence electrons

1H-5 (of

14)Slide6

PERIODIC TRENDS OF ATOMS

They involve the

attraction of either

(1)

outer shell electrons or (2) free electrons to the nucleus of an atom, and depend on

(1) The number of protons in nucleus

(2) The number of energy levels blocking or

SHIELDING

the nucleus from the outer shell or free electrons

1H-6 (of 14)Slide7

1) ATOMIC RADIUS – The distance from the nucleus to the outer shell of an atom

1H-7 (of

14)Slide8

PERIODIC TRENDS IN ATOMIC RADII

Period – The atomic radii

decrease moving to the right the outer shell electrons are attracted by an

increasing nuclear charge, while the shielding of the nuclear charge remains the sameGroup – The atomic radii increase moving down a column

even though the nuclear charge is increasing, the outer shell electrons are more shielded from the nuclear charge

Atom with the largest atomic radius ?

Atom

with the smallest atomic radius?

1H-8 (of

14)

Fr

HeSlide9

1H-9 (of

14)Slide10

Radii

V (Z = 23) 0.122 nm Nb (Z = 41)Ta (Z = 73)

EXCEPTIONS TO THE TRENDS IN ATOMIC RADII

Group

Atoms in the 5d sublevel section of the periodic table are not larger than atoms in the 4d sublevel section

0.134 nm

This is called the LANTHANIDE CONTRACTION

1H-10

(of

14)

0.134 nm

Increasing Decreasing

Factor Factor

1 more EL 18 more p

+

1 more EL

32 more p

+

Slide11

2) IONIZATION ENERGY (IE) – The energy change for the removal of an electron from a gaseous atom

X (g)

→ X+ (g) + e-

Endothermic – A process in which energy is absorbed (∆E is positive)

Exothermic – A process in which energy is released (∆E is negative) Ionization Energies are always endothermic

1H-11

(of

14)Slide12

SUCCESSIVE IONIZATION ENERGIES

Mg

(g)

→ Mg

+

(g) + e-

1

st

IE = 736 kJ/mol

Mg

+

(g)

→ Mg

2+

(g)

+ e

-

2

nd

IE = 1,451 kJ/mol

Mg

2+

(g)

→ Mg

3+

(g)

+ e

-

3

rd

IE = 7,728 kJ/mol

Mg

3+

(g)

→ Mg

4+

(g)

+ e

-

4

th

IE = 10,534 kJ/mol

Successive ionization energies always increase because successive ions have less e

-

-e

-

repulsion

1H-12

(of

14)Slide13

SUCCESSIVE IONIZATION ENERGIES

Mg

(g)

→ Mg

+

(g) + e-

1

st

IE = 736 kJ/mol

Mg

+

(g)

→ Mg

2+

(g)

+ e

-

2

nd

IE = 1,451 kJ/mol

Mg

2+

(g)

→ Mg

3+

(g)

+ e

-

3

rd

IE = 7,728 kJ/mol

Mg

3+

(g)

→ Mg

4+

(g)

+ e

-

4

th

IE = 10,534 kJ/mol

Successive ionization energies always increase because successive ions have less e

-

-e

-

repulsion

7,728 kJ/mol

10,534 kJ/mol

Small ionization energies occur when removed e

-

s are valence e

-

s, which are the most shielded from the nuclear charge

1H-13

(of

14)Slide14

Determine which atom is sodium and which atom is aluminum

1

st

IE = 578 kJ/mol

2

nd

IE = 1,817 kJ/mol

3

rd

IE = 2,745 kJ/mol

4

th

IE = 11,577 kJ/mol

1

st

IE = 496 kJ/mol

2

nd

IE = 4,562 kJ/

mol

3

rd

IE = 6,912 kJ/mol

4

th

IE = 9,543 kJ/mol

Na

Al

Atom 2

Atom 1

1H-14

(of

14)Slide15
Slide16

PERIODIC TRENDS IN 1st IONIZATION ENERGIES

Period – The 1st IE increases moving to the right the removed electron is attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the same

Group – The 1st IE decreases moving down a column even though the nuclear charge is increasing, the removed electron is more shielded from the nuclear charge

Atom with the highest 1

st

IE ?He

Atom with the lowest 1

st

IE?

Fr

1I-1

(of

19)Slide17

1I-2

(of 19)Slide18

EXCEPTIONS TO THE TRENDS IN 1st IONIZATION ENERGIESPeriod

Li Be B C N O F Ne

519 900 1088 1406 1682 2080

519 900

799

1088 1406

1314

1682 2080

1s 2s 2p

B

↑↓ ↑↓

↑

___ ___ ___ ___ ___

The removed e

-

for B is in a p orbital, whereas the removed e

-

for Be is in an s orbital - e

-

s in p orbitals are more shielded from the nuclear charge than e

-

s in s orbitals

1I-3

(of

19)Slide19

EXCEPTIONS TO THE TRENDS IN 1st IONIZATION ENERGIESPeriod

Li Be B C N O F Ne

519 900

799

1088 1406

1314

1682 2080

The removed e

-

for O is paired and experiencing e

-

-e

-

repulsion, whereas the removed e

-

for N is not

↑↓ ↑↓ ↑

↓

↑ ↑

___ ___ ___ ___ ___

O

1s 2s 2p

1I-4

(of

19)Slide20

3) ELECTRON AFFINITY (EA) – The energy change for the addition of an electron to a gaseous atom

X (g) + e-

→ X- (g)

Electron Affinities are always exothermic

1I-5

(of

19)Slide21

PERIODIC TRENDS IN ELECTRON AFFINITIESPeriod – EA

decreases (becomes more exothermic) moving to the right a free electron is attracted by an increasing nuclear charge, while the shielding of the nuclear charge remains the same (except noble gases)

Group – EA increases (becomes less exothermic) moving down a column even though the nuclear charge is increasing, a free electron is more shielded from the nuclear charge

1I-6

(of

19)Slide22

1I-7

(of 19)Slide23

EXCEPTIONS TO THE TRENDS IN 1st ELECTRON AFFINITIESGroup In the p block of the periodic table, adding e-

s to small atoms (those in the 2nd period) results in large e--e- repulsion, so their 1st EA’s are slightly less exothermic than atoms in the 3rd period

F

Cl -349 kJ/

mol

Br -343 kJ/molI -295 kJ/mol

-328 kJ/

mol

← element with the

most exothermic EA

1I-8

(of

19)Slide24

EXCEPTIONS TO THE TRENDS IN 1st ELECTRON AFFINITIESPeriod

K Ca Ga Ge As Se Br Kr

-49 -76 -116 -195 -325

-49

~0

-76 -116

-75

-195 -325

~0

The added e

-

will go into an orbital of a new sublevel, where it will be very shielded from the nuclear charge

↑↓

___ ___ ___ ___

___ ___

___ ___ ___

Ca [Ar]

4s 3d 4p

↑↓ ↑↓

↑↓

↑

↓ ↑↓ ↑↓

↑↓

↑↓ ↑↓

___ ___ ___ ___

___ ___

___ ___ ___

Kr [Ar]

1I-9

(of

19)Slide25

EXCEPTIONS TO THE TRENDS IN 1st ELECTRON AFFINITIESPeriod

K Ca Ga Ge As Se Br Kr

-49

~0

-76 -116

-75

-195 -325

~0

The added e

-

will experience e

-

-e

-

repulsion

↑↓ ↑↓

↑↓

↑

↓ ↑↓

↑↓

↑ ↑

↑

___ ___ ___ ___

___ ___

___ ___ ___

As [

Ar

]

4s 3d 4p

1I-10

(of

19)Slide26

EXCEPTIONS TO THE TRENDS IN 1st ELECTRON AFFINITIESPeriod

K Ca Ga Ge As Se Br Kr

-49

~0

-76 -116

-75

-195 -325

~0

What other two elements in the 4

th

period would you expect to have

less exothermic EA’s than the element before them?

Mn

and Zn

1I-11

(of

19)Slide27

METALS

Physical Properties – Low number of valence electrons, metallic luster, malleable, ductile, conductors of heat

and electricity, form water solutions that are basicSolids are brilliant white (or silver) except copper (red) and gold (yellow), mercury is a liquidChemical Properties – Due to the low ionization energies of their valence electrons, they can lose their valence electrons to produce positive ions (called CATIONS)

1I-12

(of

19)Slide28

Group 1 - Alkali Metals

Group 2 - Alkaline Earth Metals

Group 11 - Coinage Metals

8, 9, 10 - Fe-Co-Ni Triad - The Ferromagnetic Metals

8, 9, 10 - Noble Metals (Ru, Rh, Pd, Os, Ir, Pt)d Block - Transition Metalsf Block - Inner Transition Metals (Lanthanides and Actinides)

1I-13

(of

19)Slide29

Metal Hardness

Group 1 metals are soft, hardness increases to Group 6, and then hardness decreases to Group 16

1I-14

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19)Slide30

Metal Activity

Group 1 metals are extremely active, and activity decreases to Group 11, with the Noble Metals, Coinage Metals, and Hg being very inactive

Al and Zn are very active, and activity decreases down and to the right

1I-15

(of

19)Slide31

NONMETALS

Physical Properties – High number of valence electrons, opposite of

metals, form acidic water solutions

Some are crystalline solids, bromine is a liquid, and some are gases

Chemical Properties – Due to their highly exothermic electron affinities, they can gain electrons until their outer shells are full to produce negative ions (called ANIONS)

1I-16

(of

19)Slide32

Group 18 - Noble Gases

Group 17 - Halogens

Hydrogen - A group of its own in that it can form 1+ and 1- ions

1I-17

(of

19)Slide33

Nonmetal Activity

Group 17 nonmetals are extremely active, and activity decreases down and to the left

H is active, and the Noble Gases are inert

1I-18

(of

19)Slide34

METALLOIDS

Intermediate number of valence electrons, properties of metals and nonmetals

1I-19

(of

19)Slide35
Slide36

Hydrogen - Colorless gas (H2)Helium - Colorless gas (He)

1J-1

(of

5)Slide37

ALLOTROPES – Forms of an element with different interatomic bonding, so different properties

Boron - Crystalline brownCarbon - Crystalline as diamond, graphite, or

buckminster-fullerene; amorphous as charcoal

1J-2

(of

5)Slide38

Nitrogen - Colorless gas (N2)Oxygen - Colorless gas allotropes dioxygen (O2) and ozone (O3)Phosphorus - Crystalline red, white (P4), and black allotropes Sulfur - Crystalline yellow (S8 rings) and other allotropes (S8 chains)

1J-3

(of

5)Slide39

Fluorine - Pale yellow-green gas (F

2)Chlorine - Yellow-green gas (Cl2)

Bromine - Orange liquid (Br2)Iodine - Crystalline black (I2), sublimes to violet vaporNoble Gases - Colorless monatomic gases

1J-4

(of

5)Slide40

Bismuth (Z = 83) – The element of highest atomic number with at least one stable isotope

Plutonium (Z = 94) – The element of highest atomic number found naturally on Earth

1J-5

(of

5)Slide41

REVIEW FOR TEST 1Metric SystemDimensional AnalysisSignificant FiguresScientists

and their WorkDalton’s Atomic TheoryElectromagnetic RadiationPhotonConversions from Wavelength to Frequency to

EnergySlide42

REVIEW FOR TEST 1Bohr Model of the AtomBohr Orbit EnergyElectronic Energy Diagram

Electron Transition and Ionization EnergiesSlide43

REVIEW FOR TEST 1Schrodinger Electron Wave ModelOrbitalElectrons per Energy Level, Sublevel, Orbital

Orbital NotationElectron Configuration NotationElectron Dot NotationElectron Filling PatternEffects of Shielding on the Electron Filling PatternExceptions to the Electron Filling

PatternSlide44

REVIEW FOR TEST 1Atomic NumberIsotopesMass NumberStable and Radioactive Isotopes

Half-LifeFusionFissonOrigin of AtomsAtomic Mass

Molar MassConversions from Atoms to Moles to MassSlide45

REVIEW FOR TEST 1Period, Series

Group or FamilyAtomic Radii Trend and ExceptionsIonization Energy

Energy Equation Trend and Exceptions Successive Ionization EnergiesElectron Affinity

Equation Trend and ExceptionsSlide46

REVIEW FOR TEST 1Metals

Trends in Physical and Chemical Properties Ion ChargesNonmetals

Trends in Physical and Chemical Properties Ion ChargesMetalloidsDescriptions of Elements

AllotropesExperiments 1-5