8756

7/30/2019 8756

1/45

Chapter 4

The Periodic Table

7/30/2019 8756

2/45

4.1 Element Organization

Patterns in Element Properties

groups of elements havemuch in common

discovery (invention) ofperiodic table

1861

7/30/2019 8756

3/45



discovery (invention) ofperiodic table

1865: John Newlands (Englishchemist) noticed repeatingchemical and physical

properties every eightelements when arranged byincreasing atomic mass

thought to be absurd

7/30/2019 8756

4/45



1869: Dmitri Mendeleev madefirst periodic table

arranged elements byincreasing atomic mass

switched problem elements

made predictions for gapshe was right

nominated for Nobel prize

7/30/2019 8756

5/45



Henry Moseley (Englishchemist) found that pattern

of table was due to atomicnumber, not atomic mass

7/30/2019 8756

6/45

7/30/2019 8756

7/45

Periodic Table

7/30/2019 8756

8/45

Symbols in Table

7/30/2019 8756

9/45


The Periodic Law

similar properties are due tosimilar electron configuration

each column (group) containselements with the samenumber of electrons in the

outer energy level (valenceelectrons)

valence electrons participate

in reactions (bonding)

7/30/2019 8756

10/45


The Periodic Law

similar properties are due tosimilar electron configuration

each row (period) containselements with the samenumber of occupied energy

levels

7/30/2019 8756

11/45

4.2 Table Tour

Main-Group Elements

elements in groups 1,2,13-18

s-and p-blocks

electron configuration variesconsistently

examples

7/30/2019 8756

12/45

Main-Group Elements

7/30/2019 8756

13/45

7/30/2019 8756

14/45

4.2 Table Tour

Main-Group Elements

Group 2: alkaline-earthmetals

also very reactive, but lessthan Group 1

usually found as compounds

harder, higher melting pointsthan alkali metals

7/30/2019 8756

15/45

7/30/2019 8756

16/45

4.2 Table Tour

Main-Group Elements

Group 18: noble gases

unreactive; full set of

electrons in outer energy levelused to be called inert, butxenon was found to react

good for electric lights

7/30/2019 8756

17/45

4.2 Table Tour

Main-Group Elements

Hydrogen

about 75% of the universe

behaves unlike any otherelement

reactive

major component in organiccompounds (carbs, proteins,lipids, nucleic acids)

7/30/2019 8756

18/45

4.2 Table Tour

Metals

excellent conductors ofelectricity

100 000 x better than mostconductive nonmetal

excellent conductors of heat

l

7/30/2019 8756

19/45

Metals

bl

7/30/2019 8756

20/45

4.2 Table Tour

Metals

often ductile (can besqueezed into a wire)

often malleable (can behammered into a sheet)

often shiny

2 bl

7/30/2019 8756

21/45

4.2 Table Tour

Metals

Transition Metals (Groups 3-12)

d-block

electron configuration is notidentical in each group

do not always lose the samenumbers of valence electronsin each reaction (depends onother element

4 2 T bl T

7/30/2019 8756

22/45

4.2 Table Tour

Metals

Transition Metals (Groups 3-12)

can be found as pureelements (e.g., gold,platinum)

good conductors (both heatand electricity)

ductile and malleable

4 2 T bl T

7/30/2019 8756

23/45

4.2 Table Tour

Metals

Lanthanides and Actinides

f-block

lanthanides: atomic numbersfollow lanthanum

actinides: atomic numbers

follow actinium

shiny metals

4 2 T bl T

7/30/2019 8756

24/45

4.2 Table Tour

Metals

Lanthanides and Actinides

reactive like alkaline-earth

metalsall actinides are radioactive(e.g., uranium)

4 2 T bl T

7/30/2019 8756

25/45

4.2 Table Tour

Metals

melting points vary widely

metals can be mixed with

other metals to form alloysexamples: brass (copper andzinc), sterling silver (silver and

copper), steel (iron, carbon,manganese, nickel, chromium)

4 3 T d i P i di T bl

7/30/2019 8756

26/45

4.3 Trends in Periodic Table

Trend: predictable change in

a particular direction Ionization Energy

Ionization: removing anelectron from an atom or ion

Ionization energy: energyrequired to remove anelectron from an atom or ion

must overcome attraction

7/30/2019 8756

27/45


7/30/2019 8756

28/45


Ionization Energy

decreases as you move downa group

due to electron shielding(inner electrons shield outerelectrons from the full

attractive force of the nucleus) increases as you moveacross a period

I i ti E T d

7/30/2019 8756

29/45

Ionization Energy Trends

I i ti E G h

7/30/2019 8756

30/45

Ionization Energy Graph


7/30/2019 8756

31/45


Atomic Radius

bond radius: half thedistance from center to

center of two like atoms thatare bonded

7/30/2019 8756

32/45

4 3 Trends in Periodic Table

7/30/2019 8756

33/45


Atomic Radius

increases as you move downa group

due partly to electronshielding

decreases as you move

across a periodlevels as electrons get close to

one another

Atomic Radii Trends

7/30/2019 8756

34/45

Atomic Radii Trends

Atomic Radii Graph

7/30/2019 8756

35/45

Atomic Radii Graph


7/30/2019 8756

36/45


Electronegativity

measure of the ability of anatom in a compound to

attract electrons is calledelectronegativity

higher electronegativity means

a stronger pull on electrons


7/30/2019 8756

37/45


Electronegativity

decreases as you move downa group

due to electron shielding increases as you moveacross a period

not adding electrons to innerlevels, so stronger effective

nuclear charge

Electronegativity Trends

7/30/2019 8756

38/45

Electronegativity Trends

Electronegativity Graph

7/30/2019 8756

39/45

Electronegativity Graph


7/30/2019 8756

40/45


Ionic Size

increases as you move downa group

due to electron shieldingdecreases as you moveacross a period

due to increasing nuclearcharge, whether the ion is

positive or negative

Ionic Radii Trends

7/30/2019 8756

41/45

Ionic Radii Trends


7/30/2019 8756

42/45


Electron Affinity

the energy change thatoccurs when a neutral atom

gains an electron is calledthe atoms electron affinity

decreases as you move down

a group due totake a guess

increases as you move

across a period Electron Affinity Trends

7/30/2019 8756

43/45

Electron Affinity Trends


7/30/2019 8756

44/45


Melting and Boiling Points

peak as dand porbitals fill

bonds are stronger with half-

filled orbitals


7/30/2019 8756

45/45


Documents

8756