Chapter 6Chapter 6

The Periodic Table The Periodic Table and Periodic Lawand Periodic Law

Section 6.1Section 6.1Development of the Development of the

Modern Periodic TableModern Periodic Table

ObjectivesObjectives

• Trace the development and Identify key features of the periodic table.

HistoryHistory• 1790s, French scientist Lavoisier

•23 elements

• 1800s: electricity and spectrometer

John NewlandsJohn Newlands• Patterns of the periodic table• Law of octaves • Elements on the eights had similarities

Meyer & MendeleevMeyer & Mendeleev

• 1869-Meyer and Mendeleev: connection between atomic mass and properties

• Mendeleev published it first– Left holes of undiscovered elements– Predicted properties of undiscovered

elements- Sc, Ga, Ge

MoseleyMoseley• Problems with Mendeleev

•Rows by increasing atomic mass

• Moseley used atomic number instead

The Periodic LawThe Periodic Law

• There is a periodic repetition of chemical and physical properties of the element when they are arranged by increasing atomic number.

The Modern Periodic TableThe Modern Periodic Table

• Horizontal rows- periods• Vertical columns- groups or families

• Groups 1A through 8A = Representative Elements – Wide range of chemical and physical

properties

• Groups 1B through 8B = Transition Elements

Metals

– shiny, smooth– solid room temperature– good conductors of heat and

electricity

Alkali MetalsAlkali Metals

• Alkali Metals= 1A (excluding hydrogen) – highly reactive

Alkaline Earth MetalsAlkaline Earth Metals

• Alkaline Earth Metals= 2A– highly reactive (not

as much as 1A)

TransitionsTransitions• Transition metals

– Group B elements contained in the D block of the table

• Inner transition metals – the lanthanide and actinide series – F block

NonmetalsNonmetals– Generally a gas or a brittle, dull-looking solids– Poor conductors

• Halogens=7A – REALLY REACTIVE

• Noble Gases= 8A – unreactive and stable (all valence electrons

are filled)

MetalloidsMetalloids

– contain the physical and chemical properties of both metals and nonmetal

HomeworkHomework•Section 6.1 Assessment

–1-6 on page 158

Reactivity TrendsReactivity Trends

• Increases down the table for the metals

• Decreases down the table for the nonmetals

                                                                                                                              

          

Section 6.2Section 6.2Classification of the Classification of the

ElementsElements

ObjectivesObjectives• Explain why elements in the same

group have similar properties• Identify the four blocks of the

periodic table based on electron configuration

Valance ElectronsValance Electrons• The properties of each element in

each group are similar because they have the same number of valence electrons

Valence Electrons and Valence Electrons and Period NumberPeriod Number

• Energy level of valence electrons = period on the table

• Example: Lithium: period 2, valence electron in 2nd energy level (1s22s1)

Valence Electrons and Valence Electrons and Group NumberGroup Number

• Group number (1A-8A) = number of valence electrons

Putting it TogetherPutting it Together• Oxygen is in the 3rd period and in

group 6A.

– Oxygen’s valence electrons are located in the ____ energy level.

– Oxygen has ___ valence electrons.

S,P,D, and F BlocksS,P,D, and F Blocks• 4 different energy sublevels:

s, p, d, and f • S block= 1A and 2A

– holds max of 2 electrons

• P block= 3A through 8A– max holds 6 electrons– S block must fill before P block can fill– Noble gases are stable because of filled

S and P blocks

S,P,D, and F Blocks S,P,D, and F Blocks Continued…Continued…

• D block = transition metals – max of 10 electron

• F block= inner transition metals– unpredictable manner of filling– max of 14 electrons

Reactivity TrendsReactivity Trends

• Increases down the table for the metals

• Decreases down the table for the nonmetals

                                                                                                                              

          

HomeworkHomework• Page 162, #10-15

Periodic Trends: Atomic Periodic Trends: Atomic RadiusRadius

• For metals, atomic radius = ½ distance between adjacent nuclei in a crystal element

• For nonmetals, atomic radius = ½ distance between nuclei of identical atoms that are chemically bonded

Periodic Trends: Atomic Periodic Trends: Atomic RadiusRadiusDECREASES

INCREASES

Atomic RadiusAtomic Radius• The increase from top to bottom

is due to adding electron shells.

• The decrease from left to right is due to increased nuclear charge as you move to the right, which draws electrons closer to the nucleus.

Periodic Trends: Ionization Periodic Trends: Ionization EnergyEnergy

• Ionization energy= energy required to remove an electron from a gaseous atom

• Octet rule = atoms tend to gain lose or share electrons to acquire a full set of 8 valence electrons

Periodic Trends: Ionization Periodic Trends: Ionization EnergyEnergyINCREASES

DECREASES

Periodic Trends: Periodic Trends: Electronegativity Electronegativity

• Electronegativity= relative ability of an atom to attract electrons in a chemical bond.

ElectronegativityElectronegativity• Arbitrary units called Paulings (after

Linus Pauling) are used to express electronegativity.

• Electronegativity increases from left to right across a period and from top to bottom down a group.

Periodic Trends: Periodic Trends: ElectronegativityElectronegativity

INCREASES

DECREASES