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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).
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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 mass • 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/