Unit 2 The Periodic Table

History of the Table Is an organized chart of all the elements known to science. * most elements occur naturally [91] * some have been created in labs [27]

First Periodic Table was created in the late 1800’s by a Russian chemists named Dmitri Mendeleev.

Mendeleev put his table in order by increasing atomic mass.

It is called a periodic table because of the repeating pattern of elements. * a calendar is an example of a periodic table of days

Because of this pattern, Mendeleev predicted the discovery of 3 new elements. * he predicted their approximate mass, properties, chemical activity based on their location * he was right

* Today’s table is in order by increasing atomic numbers .

The Format of the Periodic Table Period = a row across the table * it shows the repeating pattern * each period represents an energy level * 7 periods on the table

1 2 3 4 5 6 7 6 7

The Format of the Periodic Table Family (Group) = a column up and down on the table * they have similar properties * they will react the same way * 18 families (groups) on the table

1 18 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12

Some Families have names given to them. Family 1 = Alkali Metals Family 2 = Alkaline Earth Metals Families 3 – 12 = Transitional Metals (a.k.a.: transitional elements) Family 17 = Halogens Family 18 = Noble Gases

3 Categories of Elements Metals Non-Metals Metalloids

The Format of the Periodic Table Metals are located on the left side. * solids at room temperature * mostly shiny * good conductors * malleable and ductile

The Format of the Periodic Table What makes a METAL a METAL? * its properties

The Format of the Periodic Table Non-Metals are located on the far right side. * mostly gases at room temperature * some are brittle solids * do not conduct electricity * not malleable or ductile

The Format of the Periodic Table What makes a NON-METAL a NON-METAL? * its properties

Only MERCURY (metal) and BROMINE (non-metal) are liquids at room temperature.

The Format of the Periodic Table Metalloids are located on the Stair-Step Line. * have properties of metals and non-metals * will react differently based on the situation

The Format of the Periodic Table What makes a METALLOID a METALLOID? * its properties

Color code your Periodic Table. Page 164 of the Chemistry textbook.

Information found in the Periodic Table Element name Element symbol Atomic number (# of protons) also electrons Atomic mass State of matter Family Number Period (# of energy levels)

15 Nitrogen 7 N 14.007 Family # Name Atomic # State of Symbol Matter protons & electrons 7 State of Matter Symbol N Atomic Mass 14.007 Period is found by following the row to the left. # of energy levels

Information not found in the Periodic Table # of Neutrons Mass number * the table would be TOO large * each isotope would need its own box

The Periodic Table has hidden information about each element. * you just have to know how to read what it tells you

An elements reactivity is based on the number of electrons in its outer energy (valence) level. * to be stable they need 8 electrons in their O.E.L.

How to tell how many electrons are in the outer energy level. Look at the Family (Group) Number / / / / 01 = 1 02 = 2 13 = 3 14 = 4 15 = 5 16 = 6 17 = 7 18 = 8 Does not hold true for families 3 - 12

Dot Diagram Uses the element’s symbol and a dot to represent EACH electron in its outer energy level.

Examples of Dot Diagrams Li Ca Aℓ Br Kr

Family (Group) 18 = The Noble Gases Rarely will react with other elements. Can combine under extreme circumstances.

Synthetic Elements Created in a laboratory; are not naturally occurring. * created by colliding elements and other particles together and forcing them to stick * most are radioactive

Radioactive Element An unstable element whose nucleus breaks down and gives off particles, radiation and energy.

The End