The Periodic Table of Elements

The First Periodic Table The periodic table was first discovered by Dmitri Mendeleev He arranged the elements according to similar chemical properties.

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 broke the pattern of increasing atomic weight to keep similar reacting elements together.

‘Maybe one day we’ll understand why Dmitri always lays out his blocks this way!’

The Modern Periodic Table Henry Moseley determined the atomic number of the atoms of the elements This is how he arranged the periodic table we use today.

Arrangement of the Periodic Table Periods-horizontal rows Properties of the elements within the period changes as you move across from element to element. Group-vertical rows Elements in a group have similar chemical and physical properties Each group is identified as either A or B.

Groups Group A Group B Made up of groups 1-8 Called the representative metals because the exhibit a wide range of physical and chemical properites. Group B Called the transition metals and inner transition metals.

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.

Groups…Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons. They will form the same kinds of ions.

Families on the Periodic Table Columns are also grouped into families. Families may be one column, or several columns put together. Families have names rather than numbers. (Just like your family has a common last name.)

Group A Group 1A Group 2A Group 7A Group 0A Alkali Metals Alkaline Earth Metals Group 7A Halogens Group 0A Noble gases

Group B Transition Metals Inner Transition Metals Lanthanide Series Actinide Series

Non- Metals Metals

X Properties of Metals Metals have the following properties : They conduct electrical energy well They conduct thermal energy well They are shiny They are malleable (can be hammered into shape) They are ductile (can be drawn out into wires) They are sonorous (make a ringing sound when hit) All except mercury are solids at room temperature Only a few metals are magnetic. Magnetism is not a property of most metals! X

Other elements Non metals Metaloids Intermediate properties of metals and non-metals.

Properties of Non-Metals Non-metals have the following properties : They are poor conductors of electrical energy They are poor conductors of thermal energy Many of them are gases They are brittle if they are solid Both a diamond and a pencil ‘lead’ are made of the same element – carbon.

Label the periodic table As I show you a part of the periodic table, we are going to color code it and label it.

Hydrogen Hydrogen belongs to a family of its own. Hydrogen is a diatomic, reactive gas. Hydrogen was involved in the explosion of the Hindenberg. Hydrogen is promising as an alternative fuel source for automobiles

Alkali Metals 1st column on the periodic table (Group 1) not including hydrogen. Very reactive metals, 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 are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

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

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

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.

Periodic trends Effective Nuclear Charge In a many-electron atom, electrons are both attracted to the nucleus and repelled by other electrons. The nuclear charge that an electron experiences depends on both factors. http://prezi.com/to5idg9l9qvd/periodic-table-trends/