“The Periodic Table”

Mendeleev’s Periodic Table By the mid-1800s, about 70 elements were known to exist Dmitri Mendeleev – a Russian chemist and teacher Arranged elements in order of increasing atomic mass Thus, the first “Periodic Table.”

Horizontal rows = periods There are 7 periods The Periodic Law says: Horizontal rows = periods There are 7 periods Same number of energy levels Vertical column = group (or family) There are 18 groups. Similar physical & chemical prop. Identified by number & letter (IA, IIA)

Areas of the periodic table Three classes of elements are: 1)metals, 2)nonmetals, and 3)metalloids Metals: electrical conductors, have luster, ductile, malleable. Are on the left side of the periodic table. Nonmetals: generally brittle and non-lustrous, poor conductors of heat and electricity

Areas of the periodic table Some nonmetals are gases (O, N, Cl); some are brittle solids (S); one is a fuming dark red liquid (Br) Are on the right side of the periodic table Notice the heavy, stair-step line? Metalloids: border the line-2 sides Properties are intermediate between metals and nonmetals Live on or below the bold line

A. Metallic Character Metals Nonmetals Metalloids

Squares in the Periodic Table The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms: Atomic number and atomic mass Black symbol = solid; red = gas; blue = liquid (from the Periodic Table on our classroom wall)

Groups of elements - family names Group IA – alkali metals Forms a “base” (or alkali) when reacting with water (not just dissolved!) have 1 electron in their outermost shell Group 2A – alkaline earth metals Also form bases with water; do not dissolve well, hence “earth metals” have 2 electrons in their outermost shell Group 3A – boron family have 3 electrons in their outermost shell Group 4A – carbon family have 4 electrons in their outermost shell

Groups of elements - family names Group 5A – nitrogen family (pnitogen) have 5 electrons in their outermost shell Group 6A –oxygen family have 6 electrons in their outermost shell Group 7A – halogens Means “salt-forming” have 7 electrons in their outermost shell Group 8A – noble gases Have 8 electrons in their outermost shell

Electron Configurations in Groups Elements can be sorted into 4 different groupings based on their electron configurations: Transition metals Filling D orbital Inner transition metals Filling F orbital Representative elements Filling S or P orbital Noble gases FULL outer orbital