Families of Elements

The Periodic Table 1871: Dmitri Mendeleev created first periodic table Arranged all the known elements by atomic mass. Noticed that the similarities in their chemical properties appeared at regular intervals (periodic). Moved elements into different groups if they had similar properties. Left gaps for elements not yet discovered. “In a dream I saw a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper.” -Dmitri Mendeleev, 1834 to 1907 Chemist

The photograph shows a giant wall Periodic Table erected in St Petersburg, Russia, in 1934. Elements in black were discovered between Mendeleev's death and 1934.

The Periodic Table 1913: Henry Moseley concluded that atomic number not atomic mass should be used to arrange the periodic table. Periodic Law: The physical and chemical properties of the elements are periodic functions of their atomic numbers.

Families on the Periodic Table Elements on the periodic table can be grouped into families bases on their chemical properties. Each family has a specific name to differentiate it from the other families in the periodic table. Elements in each family react differently with other elements.

Families on the Periodic Table Metals Nonmetals Semi-conductors/Metalloids

Metals: Left-side of table (except for Hydrogen) Shiny conducts heat and electricity well can be stretched and shaped usually solids make cations

Nonmetals: Right-side of table (except for Hydrogen) may be solid, liquid, or gas typically dull and brittle poor conductors make anions

Semi-conductors: Where the metals and non-metals meet also called metalloids nonmetals that conduct under certain conditions Only 6: Boron Silicon Germanium Arsenic Antimony Tellurium

ALKALI METALS Group 1 Hydrogen is not a member, it is a non-metal All are metals and solid at room temp 1 Valence Electron Create +1 ions Soft and silvery, shiny Very reactive, esp. with water Conduct electricity Image: http://www.learner.org/interactives/periodic/groups2.html

ALKALINE EARTH METALS Group 2 Metals Solids at room temp 2 electrons in the outer shell Create +2 ions White, silvery, and malleable Reactive, but less than Alkali metals Conduct electricity

TRANSITION METALS Metals Almost all are solids at room temp (Hg) Good conductors of heat and electricity. 1 or 2 Valence Electrons Can create up to 4 different cations Less Reactive than Alkali and Alkaline Earth Can bond with many elements in a variety of shapes.

BORON FAMILY Group 13 3 electrons in the outer shell Most are metals Boron is a metalloid Reactive Solid at room temp

CARBON FAMILY Group 14 4 electrons in the outer shell Contains 3 metals, 2 metalloids, and 1 non-metal Carbon (C) Reactivity varies Solids at room temp

NITROGEN FAMILY Group 15 5 electrons in the outer shell Can share electrons to form compounds Contains 2 metals, 2 metalloids, and 2 non-metals Reactivity Varies Nitrogen is the only gas at room temp, rest are solids

OXYGEN FAMILY Group 16 6 electrons in the outer shell Create -2 ions Contains 2 metals, 1 metalloid, and 3 non-metals Reactive Oxygen is a gas, the rest are solids at room temp

Halogens Group 17 7 electrons in the outer shell Create -1 ions Non-metals, Uus is unknown Very reactive - are often bonded with Group 1 Alkali Metals Has 2 gases, 1 liquid (Br), and 2 solids

Noble Gases Group 18 Exist as gases Non-metals 8 electrons in the outer shell = Full Helium (He) has only 2 electrons in the outer shell = Full Not reactive with other elements

Rare Earth Metals Some are Radioactive The rare earths are silver, silvery-white, or gray metals. Conduct electricity

Other Trends: Number of protons Atomic radius Atomic mass Ionic radius Valence electrons Number of energy levels Atomic radius Ionic radius Ionization energy (energy required to remove one electron from a neutral atom of an element) Electronegativity (ability of an atom in a chemical compound to attract electrons)

You may watch more videos about the elements at: http://www.periodicvideos.com/