During the 19th century, chemists began to categorize

the elements according to similarities in their physical and

chemical properties.

The end result of these studies was our modern periodic table.

Dmitri Mendeleev

1834 - 1907

In 1869 he published a table of the elements organized by increasing atomic mass.

Henry Moseley

1887 - 1915

In 1913, through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements*. He rearranged the elements in order of increasing atomic number.*“There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

Periodic Law

When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

The horizontal rows of the periodic table are called PERIODS.

The vertical columns of the periodic table are called GROUPS, or FAMILIES.

The elements in any group of the periodic table have similar physical and chemical properties!

Atomic number is the key to the

organization of the periodic table!!!

Elements are listed by atomic number!

Metals

•Conductors

• Ductile (can be drawn into wires)

• Malleable (can be hammered out)

Form cations (+ charged ions)

Nonmetals

•Poor Conductors

•Good Heat Insulators

•Nonductile

Form anions (- charged ions)

Metalloids

•Show properties of metal and nonmetals

•“Semiconductors” POLONIUM NOT A METALLOID!

Alkali Metals – Group 1

Group 1 - The Alkali Metals

A. Group one is the first column of the periodic table on the left. The alkali metals group consists of the elements lithium, sodium, potassium, rubidium, cesium, and francium.

NaCl

Group 1 - The Alkali Metals

B. The alkali metals are very reactive metals that do not occur freely in nature.

C. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements.

Group 1 - The Alkali Metals

D. All of the group 1 elements are silvery-colored metals. They are soft, and can be cut easily with a knife.

E. The alkali metals are malleable and good conductors of heat and electricity. They have low densities - Li, Na, and K are less dense than water.

Group 1 - The Alkali Metals

F. Alkali metals can explode if they are exposed to water.

Alkaline Earth Metals Group 2

Group 2 -The Alkaline Earth Metals

A. The alkaline earth metals are elements found in the second group of the periodic table. The alkaline earth metals consist of the elements beryllium, magnesium, calcium, strontium, barium, and radium.Yum! Calcium!

Group 2 -The Alkaline Earth Metals

B. All alkaline earth metals have 2 electrons in their outer energy shell, so they are very reactive - although not as reactive as the alkali metals.

C. Because of their high reactivity, alkaline earth metals are not found freely in nature.

Group 2 - The Alkaline Earth Metals

D. All alkaline earth metals are shiny, silvery white metals. If heated in a flame, each of the metals will give a different colored flame.

Transition Metals Group 3-12

Groups 3 –12 : Transition Metals

A. The 38 elements in groups 3 through 12 of the periodic table are called “transition metals” or d-Block elements.

B. The transition metals have different numbers of valance electrons in their outer energy level.

Groups 3-12: Transition Metals

C. The transition metals have an additional energy level, or energy shell, that fills with electrons. Transition metals have valance electrons in their outer shell and in their d-shell.

D. All transition elements are mallable, and conduct electricity and heat. All transition metals except copper and gold have a silvery appearance.

Groups 3-12: Transition Metals

E. The transition metals iron, cobalt, and nickel are the only elements known to produce a magnetic field.

Groups 13 –15 : Other Metals

A. The seven elements classified as other metals are located in groups 13, 14, and 15. The other metals include aluminum, gallium, indium, tin, thallium, lead, and bismuth.

Al Recycling

Groups 13-15: Other Metals

B. While the other metals have some similarities to transition metals, they are not the same. The other metals have valance electrons only in their outer shell.

C. All other metals are solid, have a relatively high density, and are opaque.

Stair-Step Elements: Metalloids

A. Metalloids are the elements found along the stair-step line that distinguishes the metals from non-metals. The metalloid elements are boron, silicon, germanium, arsenic, antimony, tellurium, polonium.

Stair- Step Elements: Metalloids

B. Metalloids have properties of both metals and non-metals.

C. Some metalloids, such as silicon and germanium, are semi-conductors. This means that they can carry an electrical charge under special conditions. This property makes metalloids useful in computers and calculators.

Groups 14-16: Non-Metals

A. Non-metals are the elements in groups 14-16 of the periodic table. The non-metals include hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium.

Carbon Burning

Groups 14-16: Non-Metals

B. non-metals are not able to conduct electricity or heat very well. As opposed to metals, non-metals are very brittle, and cannot be rolled into wires or pounded into sheets.

C. The non-metals exist as gasses or solids at room temperature.

Groups 14-16: Non-Metals

D. The non-metals have no metallic luster (they’re not shiny), and do not reflect light.

Oxygen tank pressure gauge

Halogens – VII- A

Group 17 - The Halogens

A. The halogens all have 7 electrons in their outer-most energy level. The halogens are very reactive, and are found in nature as diatomic molecules, which means that each atom is bonded to another atom. So halogens are found in groups of two atoms bonded together.

Group 17 - The Halogens

B. The halogen group includes fluorine, chlorine,bromine, iodine, and astatine.

Chlorinated Pool

Group 17 - The Halogens

C. The physical appearances of the halogens is very different between element.

D. Fluorine is a poisonous pale yellow gas, chlorine is a poisonous pale green gas, bromine is a toxic and caustic brown liquid, and iodine is a shiny black solid which forms a purple vapor upon heating.

Noble Gases VIII-A

Group 18 - The Noble Gasses

A. The noble gasses all have full outer electron shells. That means that noble gasses will not react with any other elements.

B. The noble gasses include helium, neon, argon, krypton, xenon, and radon.

Group 18 - The Noble GassesC. All elements in group 18 are found at room

temperature as gasses, and they have very low boiling points.

Reno, NV Neon

InnerTransition Metals

These elements are also called the rare-earth

elements.

The Rare Earth Elements

A. All of the rare earth elements are found in group 3 and periods 6 and 7 of the periodic table. The rare earth elements, or lanthanide and actinide series, are mostly man-made. One of the lanthanides (period 6) and ALL of the actinides (period 7) are man-made.

The Group “A” elementsare called

REPRESENTATIVE ELEMENTS.

The periodic table is the most important tool in the chemist’s

toolbox!