Periodic Table

I. Dimitri Mendeleev 1860’s First to publish periodic table arranged by atomic mass (was changed later (1913) to arrangement by atomic number)

II Design A. Periods 1) Horizontal rows (side to side) 2) Elements in a period have the same number of energy levels B. Groups (families) 1) Vertical columns (Up and down) 2) Elements in the same group have similar properties 3) Same # outer electrons (valence e-)

Periods » Groups

II Design Cont. C. Separated into metals, non-metals and metalloids. 1) Dark, diagonal, stair step line (near the right side) divides: a. metals on the left b. nonmetals on the right c. metalloids on either side of stairs

Metals (left of zig zag) a) shiny b) malleable (bendy and can be flattened) c) good heat conductor ex) hot pan, side of toaster, car in summer d) good energy conductor ex) don’t stick a fork in a socket or toaster e) easily loses valence electrons

Nonmetals (right of zig zag) a) dull b) brittle (it breaks easily) c) poor conductor of heat ex) plastic spatula, insulated coffee mug d) poor conductor of electricity ex) electrical wires covered in plastic to protect you e) Tend to gain valence electrons C

Metalloids a) are the elements along (on either side) of that dark stair-step zig zag line. b) Have properties of both metals and nonmetals.

Periods » Groups

III Groups and Periods Group 1 – Alkali metals (Li group) –Extremely reactive metals –Easily gives away that 1 Valence electron in the outer level –Reacts violently with water –(Used to produce chemicals, metals, soap, glass, ceramics, petroleum products)

Group 2 (Be group) Alkaline-earth* Metals –2 e- in outermost shell –Very reactive metals, but not as reactive as group 1 because they have to give away two e- vs. just one. **Notice the 2 word name for group 2!**

Groups 3-12: Transition Metals A. Vary in metallic properties (all solid except Hg) B. Include the lanthanides and actinides (at the very bottom of table)

Group 17 Halogens –Extremely reactive nonmetals –Have 7 outer e- and need just 1 more to be full (so they steal it!) –Exhibit all 3 physical states at room temp.

Group 18 (8a) Noble gases Unreactive nonmetals Full outer shell of 8 e- (happiest elements of all) Also called the inert gasses Too “noble” too react with anyone else (Full shell = not interested)

Hydrogen: Odd man out –Is its own group –Does not match any other groups –1 e- in outer level so it is placed above group 1 –Behaves more like a nonmetal (other side of the table)