THE PERIODIC TABLEOrganized by Dmitri Mendeleev in 1871

PERIODS

A row on the table is called a PERIOD.

The boxes lie in order of increasing atomic number (# of protons) as you move from left to right.

TRENDS AMONG PERIODS

• Atomic mass generally increases from left to right.

• Metallic character decreases from left to right.

• Electrons are added one at a time as you move from left to right on the table.

• Elements in periods have different chemical properties.

GROUPS OR FAMILIES

Each column is called aGROUP or FAMILY.

Atomic mass increases asYou move down a group!

Elements in a group are knowto have the same number ofvalence electrons and similarchemical and physical properties.

VALENCE ELECTRONS

• The number electrons in the outermost shell.

• Is the same down a group and increases by one as you move from left to right.

LEWIS DOT STRUCTURES

ALKALI METALS

• The ALKALI METALS are the most reactive metals.

• Reactivity increases as you move down group 1A, wants to lose an electron.

• These metals are soft with low melting points and boiling points.

• Density increases down the group.

ALKALI EARTH METALS

• ALKALI EARTH METALS are in group 2A and are not as reactive as group 1A, but are more reactive than most metals.

• These metals are soft, but harder than group 1A metals.

• 2A melting and boiling points are much higher than 1A, but decrease down a group.

• Densities generally increase down the group.

REPRESENTATIVE METALS

• Alkali Metals and the Alkali Earth Metals make up the REPRESENTATIVE METALS or MAIN-GROUP METALS along with some nonmetals in 3A, 4A and 5A.

TRANSITION METALS• All transition elements are metals.• Densities increase greatly down a group.• Increase in reactivity down a group.• Transition metal compounds have striking colors.

copper(II) sulfate pentahydrate

INNER TRANSITION METALS

• LANTHANIDES are silvery and high melting metals. Very difficult to separate.– Used for tinting sunglasses– Adding color to TV screens

• ACTINIDES are radioactive.– Silvery– Form highly colored compounds

METALS

• Generally shiny solids at room temperature.• Mercury is the only liquid.• Conduct heat and electricity well.• Are malleable – hammered or shaped under

pressure without breaking.• And Ductile - Ductility is the physical property of

being capable of sustaining large plasticdeformations without fracture (in metals, such as being drawn into a wire).

NONMETALS• NONMETALS are located in the upper right quarter of the table.• Not shiny, with low melting points.• Gases or brittle solids at room temperature.• Typically poor conductors of heat and electricity. (Carbon in

graphite form is a good conductor but it is a nonmetal)

HALOGENS• Reactive nonmetals, wants to

gain 1 electron.

• Melting and Boiling Points increase down the group.

• Exist as diatomic molecules.

• React with most metals and nonmetals.

• Chlorine is the most industrially useful halogen. For example, NaCl.

• Density increases down a group.

NOBLE GASES

• All noble gases have the maximum number of electrons possible in their outer shell (2 for Helium, 8 for all others), making them stable, “inert”.

• Very low, if any, reactivity.

• Melting and Boiling Points are extremely low.

• Density increases as you move down the group.

METALLOIDS• Metalloids physical properties are more like that of

metals, but chemical reactivity is more like nonmetals.• Many properties are some where in between metals

and nonmetals.• Most useful b/c they vary in ability to conduct

electricity. This property makes metalloids useful in computers and calculators.

PREDICTIONS

Just like the weather data…We could predict

where on the periodic table of elements a new

element would be placed, based on it’s atomic

mass and chemical and physical properties.