THE PERIODIC TABLE

Elements

Science has come along way since Aristotle’s theory of Air, Water, Fire, and Earth.

Scientists have identified 90 naturally occurring elements, and created about 28 others.

Pre-Periodic Table Chemistry …

…was a mess!!! No organization of

elements. Imagine going to a

grocery store with no organization!!

Difficult to find information.

Chemistry didn’t make sense.

Why is the Periodic Table important to me?

The periodic table is a most useful tool for the chemist.

It organizes lots of information about all the known elements.

You get to use it on every Physical Science test.

Dmitri Mendeleev: Father of the Periodic Table

HOW HIS WORKED in 1869…

Put elements in rows by increasing atomic mass.

Put elements in columns by the way they reacted or their properties.

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.

Mendeleev's Periodic Table

(1871)

                                                                     

The Current Periodic Table

Mendeleev wasn’t too far off. Now elements are put in rows by

increasing ATOMIC NUMBER!! Number of Protons

The horizontal rows are called periods and are labeled from 1 to 7

The vertical columns called groups or families are chemically similar and labeled from 1 to 18.

Quick quiz

1. Name the two properties that Mendeleev used to arrange his Periodic Table?

2. When was Mendeleev working on his Periodic Table?

3. How did the answer of #1 change as we moved to the Modern Periodic Table?

Valence Electrons

The valence electrons are the electrons in the last shell or energy level of an atom. They show a repeating or periodic pattern. The valence electrons increase in number as you go across a period.

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 and bonds.

Metals vs Non-Metals

Metals are found to the left of the staircase

All will lose e-’s to form +IONS

Good conductors of heat and electricity

Malleable and ductile

Shiny & hard High MP/BP React with Acids

producing Hydrogen

Non-metals are right of the staircase

All will gain e-’s to form - IONS

Poor conductors of heat and electricity

Brittle Not shiny & softer Low MP/BP Don’t react w/ Acids

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.)

Hydrogen FamilyThe First Family and Element

Hydrogen belongs to a Family of its own because it does not react like the others in the 1st column

Hydrogen is a diatomic, VERY REACTIVE GAS and involved in many chemical reactions.

Hydrogen was involved in the Hindenburg explosion

Hydrogen is promising as an alternative fuel source for the future

1 valence e- Forms a +1 or -1 ion http://video.google.com/videosea

rch?q=Hindenburg#

Alkali Metal Family 1st column on the periodic table

(Group 1) not including Hydrogen. Very reactive METALS, always

combined with something else in nature (like in salt, NaCl). Never found as individual atoms.

These metals explode in water http://www.periodictable.com/Stories/011.2/index.html

Soft enough to cut with a butter knife. Low MP/BP.

1 valence e-, Forms a +1 Ion

Quick Quiz

1. Why is Hydrogen not included in the Alkali Family?

2. Are Alkali Metals known for their lack of chemical activity?

3. Are Alkali Metals stored underwater so they cannot come in contact with the Oxygen in the air and begin to oxidize?

4. If Hydrogen becomes a substitute for petroleum fuels, will cars become much less safe than today’s vehicles?

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 in bones and Ca in teeth and bones.

2 valence e-’s Form a +2 Ion

Transition Metals

Elements in groups 3-12

Less reactive harder metals

Includes metals used in jewelry, coins and construction.

Metals used “as metal.”

Valence e-’s don’t count

Boron Family Elements in group 13 Aluminum metal was once rare

and expensive as Gold. Not a “disposable metal.” Aluminum is very strong yet light weight. Used in aircraft “skin” and Coke cans.

Has now been discovered in a very common ore called Bauxite therefore Aluminum is less expensive now

Family has 3 valence e-’s Forms a +3 ion

Rare Earth Elements

Lanthanide Series

Atomic Numbers 57-71 Not periodic Unpredictable Most are Radioactive Most have few useful

purposes

Actinide Series

Atomic Numbers 90-103

Uranium is heaviest natural element (92)

Heavier elements are man-made ONLY

All element above 92 are Radioactive

Also not very useful

Carbon Family Elements in group 14 Contains CARBON which is

the basis of all living things

Carbon is the basis for Organic Chemistry.

Silicon and Germanium are important in computers as

semiconductors. Form the most, strongest

bonds 4 valence e-’s

Journal of Chemical EducationDOI: 10.1021/ed200142g

Nitrogen Family Elements in group 15 Nitrogen makes up 78% of the

atmosphere. (Stable form) Nitrogen and phosphorus are

both important in living things (proteins and amino acids).

Most of the world’s nitrogen is not available to living things.

Nitrogen in some forms is unstable and found in explosives (TNT) and fertilizers

The red stuff on match heads is Phosphorus

5 valence e-

Oxygen Family

Elements in group 16 Oxygen is necessary

for respiration and combustion(burning)

Many things that stink, contain Sulfur (rotten eggs, garlic, skunks,etc.)

6 valence e-

Halogens - Deadly

Elements in group 17 F, Cl, Br, I

Very reactive, volatile, diatomic, nonmetals

VERY TOXIC, THEY WILL KILL YOU

Always found combined with other elements in nature .

Used to kill bacteria and to strengthen teeth.

7 valence e-’s

Quick Quiz

1. What element is most often associated with explosives?

2. What element is frequently associated with bad smelling products?

3. If your toothpaste has Sodium Fluoride, what is it doing for you?

4. What properties of Carbon cause it to be the “Basis of Life”?

The Noble Gases

Helium, Neon, Argon, Krypton, Xenon, Radon and UnUnoctium(118)

The Noble Gases Elements in group 18 VERY UNREACTIVE

monatomic gases Used in lighted “neon” signs

and light bulbs Helium is used to fix the

Hindenburg problem and balloons.

Have a full outer shell 2, 8 or 18 valence e-’s.