How can you find anything in all these numbers and letters!?! The Periodic Table How can you find anything in all these numbers and letters!?!

Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Difficult to find information. Chemistry didn’t make sense. Why do things react like they do???

Dmitri Mendeleev: Father of the Table HOW HIS WORKED… Put elements in rows by increasing atomic weight. Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He had to break his own pattern of increasing atomic weight to keep similar reacting elements together.

The Current Periodic Table Mendeleev wasn’t too far off. Now the elements are put in rows by increasing ATOMIC NUMBER!! The horizontal rows are called periods and are labeled from 1 to 7. The vertical columns are called groups are labeled from 1 to 18.

Are you with me? 1. How did Mendeleev organize his table? 2. What direction do groups go? 3. What is different about today’s periodic table than the way Mendeleev did his table? 4. What direction do periods go?

Families or Groups on the Periodic Table Columns on the P.T. are organized into families or groups. Each groups or family is represented by names rather than numbers. (Just like your family has a common last name.)

Groups…Here’s Where the Periodic Table Gets Useful!! Why?? It’s related to their electrons, specifically all atoms in a group have the same number of valence electrons. They will form the same kinds of ions. Elements in the same group have similar chemical and physical properties!!

Alkali Metals 1st column on the periodic table (Group 1) including hydrogen. Very reactive elements, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife

Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals that give off lots of different colors when burned. Several of these elements are important mineral nutrients. Which ones?

Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

Boron Family Group 13 Boron is the only metalloid in the group and has many different properties – used in fiberglass and ceramics. Plant cells use Boron to strengthen plant walls. Aluminum metal was once rare and expensive, not a “disposable metal.” Gallium used in LED lighting and used to make mirrors.

Carbon Family Group 14 Carbon is the basis for an entire branch of chemistry, used in steel production, graphite, and carbon fiber. Silicon is an important semiconductor used in computer applications. Tin used in soldering, joining metals. Most Lead is used to create batteries.

Nitrogen Family Group 15 Nitrogen makes up over ¾ of the air we breath. Also as part of our biology used in DNA and Amino Acids Phosphorus is also important in the body and used in fertilizers. Elemental Arsenic can be toxic if ingested.

Oxygen Group – AKA Chalcogens Elements in group 16 Oxygen is necessary for respiration and photosynthesis. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature . Used as disinfectants and to strengthen teeth.

The Noble Gases Elements in group 18 Very unreactive, monatomic gases Used in lighted “neon” signs Used in blimps to fix the Hindenberg problem. Have a full valence shell.

Metalloids A collection of elements that fall on the “staircase” and divide the metals from the nonmetals Because these elements are between metals and nonmetals, they are described as having properties of both metals and nonmetals!

Lanthanide Contains 14 different elements Are used as catalyst in petroleum products, as well as lasers, magnets, and motion picture projectors. Many scientific and industrials uses

Actinides All of these elements are radioactive. Uranium and Plutonium used in Nuclear power plants and bombs They react with water and acids to produce Hydrogen. Many of these were created by scientist.