Pre-class Activity

How are library books classified?

Why is such a classification system valuable?

History of the Periodic Table

John Newlands (1864)Recognized that when

atoms are arranged by increasing mass, their properties repeated every eighth element which he named the “law of octaves”

Elements with similar properties were arranged in the same row

Did not work for all known elements

Dimitri Mendeleev (1869)Organized the first

periodic tableArranged elements by

increasing atomic massWas able to predict the

existence and properties of yet undiscovered elements

Modern Day Periodic Table

Henry Moseley

o Arranged elements according to increasing atomic number instead of increasing atomic mass

o Demonstrated a periodic repetition of chemical and physical properties called the periodic law

Organization of the Periodic Table

Group

Period

Questions

What is the location, by group and period, of Boron?

Group 13 Period 2

Which element is found in group 9, period 5?

Rhodium

Main Group or Representative Group Elements

s-blockp-block

1A

2A 3A 7A6A5A4A

8A

Transition Elements

d-block

f-block

Metals, Metalloids, and Nonmetals

Metalloids

Metals

Inner Transition Metals

Transition Metals

Alkali M

etal

sAlka

line

Earth

Met

als

Oth

er M

etal

s

Properties of Metals

Shiny

Smooth

Solid at room temp

Malleable

Ductible

Conduct Electricity

Metalloids (Semimetals)

13 14 15 16 17

BBoron

CCarbon

NNitrogen

OOxygen

FFluorine

AlAluminium

SiSilicon

PPhosphorus

SSulfur

ClChlorine

GaGallium

GeGermanium

AsArsenic

SeSelenium

BrBromine

InIndium

SnTin

SbAntimony

TeTellurium

IIodine

TlThallium

PbLead

BiBismuth

PoPolonium

AtAstatine

Metalloids contain physical and chemical properties of both metals and non-metals

Nonmetals

Hal

ogen

sN

oble

Gas

es

Nonmetals are generally gases or brittle, dull-looking solids. They are poor conductors of electricity.

Valence Electrons

For the Representative Elements, the group number corresponds to the number of valence electrons of atoms in that group.

classification of Elements

1

7

2

6

3

5

4

5

6

34

5

4

s block p block

d block

f block

Questions

How many valence electrons does Antimony (Sb) have? What is it’s Lewis Dot structure?

5 Sb

Which element is represented by the following electron configuration?

[Xe] 6s24f143d8

Platinum (Pt)

Periodic Trends in Atomic Radii

From one group to the next, atomic radius decreases because the the electrostatic attraction between increasingly larger nuclei increases, pulling the electrons closer to the nucleus

Decreases

Increases

From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus

Periodic Trends in Ionic Radii

Decreases

Decreases

Increases

From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus

For positive ions, charge numbers increase as more electrons are lost from the atom. The electrostatic force is greater for smaller numbers of electrons which decreases the ionic radius.

For negative ions, as the charge number increases, so does the number of electrons. Electrostatic forces decrease and the ionic radius increases in size.

Periodic Trends in Ionization Energy

Increased nuclear charge that occurs from one group to the next accounts for electrons being held more tightly within the atom. The more tightly they are held, the greater the amount of energy that is required to remove and electron from an atom.

The amount of energy required to remove an electron from an atom

Increase

Decrease

From one row to the next, ionization energy increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus

Periodic Trends in ElectronegativityAbility of an atom to attract electrons

Increase

Decrease