1. History, Groups, and Info on the Periodic Table
9/4/08

2. Almost a Decade Later Part I: History of the PT
by 1860, more than 60 elements had been discovered (this is almost 40 years before the Thomson model debuted).
however, there was no uniform way established to measure atomic masses accurately, and therefore…
chemical formulas were almost impossible to determine correctly.
September 1860—Germany—group of chemists assembled to settle the issue of atomic mass (and other misunderstood atomic matters).
Cannizarro, Stanislao—presented accurate method to measure atomic mass.
Mendeleev, Dimitri—1869—used this new information to organize and arrange the elements (this is the 1st time it was attempted).
Almost a Decade Later
Cannizarro

3. Mendeleev, Dimitri—1869—used this new information to
organize and arrange the elements (this is the 1st time
it was attempted).
arranged the elements according to known properties
and in order of increasing atomic weight
he noticed a trend—by arranging elements in 6 rows, he noticed a repeat in their properties down each column (this is known as a periodic pattern).
Mendeleev

4. he noticed a trend—by arranging elements in 6 rows, he noticed a repeat in their properties down each column (this is known as a periodic pattern).
some elements had not yet
been discovered, so he left
spaces for them. He also
predicted what properties
these undiscovered
elements would have.
later on, the elements that would fit in those spaces were discovered, and their properties matched what he predicted.
some discrepancies existed (iodine and tellurium).

5. Part II: Groups of the PT
Moseley, Henry—1911—used Mendeleev’s PT to write the
periodic law.
periodic law: the physical and chemical properties of the elements are periodic functions of their
atomic numbers.
he arranged elements in order of atomic number,
not weight.
Today’s PT is arranged by atomic number, thanks to
Moseley.
Part II: Groups of the PT
on the PT, a horizontal row is called a period, and a vertical column is a group.
sometimes, other parts (other than single columns) are referred to as “groups.”
each group of the PT shares similar chemical and physical properties.
intensity of these properties tends to increase down a group.
Moseley

6. each group of the PT shares similar chemical and physical properties.
Family
Period

7. alkali metals = very reactive with most substances, especially water and air. Form oxides easily, have a silvery appearance. Soft in pure form —can be cut with knife. Stored under kerosene or mineral oil.
(e- config ends in s1) Na H
Na reacting with H2O
alkali metals

8. alkaline-earth metals
alkaline-earth metals = not as reactive as alkali metals. Harder, denser, and stronger. Have higher melting points. Form alkaline solutions when dissolved in water (pH >7). (e- config ends in s2) Mg H
Ba in oil
alkali metals
alkaline-earth metals

9. alkaline-earth metals
transition metals = good conductors of electricity and heat. High luster. Less reactive than first 2 groups. Some exist as free elements (Pd, Pt, Au, Cu, Ag). Ductile (can be pulled into a wire), malleable (can be hammered, rolled into thin sheets). (e- config ends in d1-10) H Mn
alkali metals
alkaline-earth metals
transition metals Cu

10. alkaline-earth metals
The p-block is divided into three types of elements:
p-block metals: elements below the metalloid line. Very similar to the s- and d-block metals.
nonmetals: elements above the metalloid line. Are brittle, non-conductors, some gases (includes H). Ga H
nonmetals
alkali metals
alkaline-earth metals
transition metals
p-block metals P

11. alkaline-earth metals
metalloids: on the metalloid line = B, Si, Ge, As, Sb, Te. Have properties of metals and nonmetals. Semiconductors.
halogens = highly reactive nonmetals. React with metals to form salts. Used in halogen lighting. (e- config ends in s2p5) H
nonmetals Si
metalloids
halogens
alkali metals
alkaline-earth metals
transition metals
p-block metals I

12. alkaline-earth metals
noble gases: unreactive. Very rarely form compounds with any element. Used in neon signs. (e- config ends in s2p6)
lanthanides = top row of f-block. Very similar in chemical properties. Mostly natural. (e- config ends in 6s24f1-14).
actinides = bottom row of f-block. Very similar in chemical properties. Mostly synthetic. Some used in nuclear chemistry.
(e-config. ends in 7s25f1-14). Xe H Nd
nonmetals
metalloids
noble gases
halogens
alkali metals
alkaline-earth metals
p-block metals U
transition metals
lanthanides
actinides