the periodic table valence electrons electrons farthest away from the nucleus are most loosely held....

The Periodic Table

Valence Electrons

• Electrons farthest away from the nucleus are most loosely held.

• Ranges from 1 to 8 valence electrons

• Many properties of the atom, and therefore of an element, are determined by the number of valence electrons.

http://www.tutorvista.com/content/science/science-i/structure-atom/valence-shell-electron.php

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.

Dmitri Mendeleev: Created The Periodic Table

HOW HIS WORKED… Elements arranged in

rows (periods) by increasing atomic mass.

Elements arranged in columns (families) by the way they reacted.

SOME PROBLEMS… Left blank spaces for

what he said were undiscovered elements. (Turned out he was right!)

Pattern of increasing atomic mass was broken to keep similar reacting elements together.

http://upload.wikimedia.org/wikipedia/commons/b/b3/Medeleeff_by_repin.jpg

The Current Periodic Table

In 1913, Henry G.J. Moseley, an English scientist, arranged the elements based on increasing atomic number.

http://www.chemistryexplained.com/Ma-Na/Moseley-Henry.html

Groups

Vertical columns are called groups or families Groups are numbered 1 to 18.

Groups…Here’s Where the Periodic Table Gets Useful!!

Elements in the same group have similar chemical and physical properties!!

Example: Elements in Group 1 are highly reactive and can be explosive in water.

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They have the same number of valence electrons.

http://www.tutorvista.com/content/science/science-i/structure-atom/valence-shell-electron.php

Why?

Periods

• Horizontal rows numbered 1 to 7.

• Elements in the same period have the same number of electron rings or energy levels.

Metals:Metals:

•Left/Middle of Periodic Table•Give up valence electron in a reaction• Shiny, metallic• Conduct heat and electricity• Malleable and ductile (reshape)

Copper

Nickel

Aluminum

Gold

Silver

Mercury

Metalloids:Metalloids:

• Zigzag on Periodic Table where metals and nonmetals meet

• Mostly shiny, metallic looking• Only semi-conductive• Often combined with non-metals

Non-Metals:Non-Metals:

•Right side of Periodic Table•Gain or share electrons in a chemical reaction•Dull, not shiny, many are GAS• Do not conduct heat or electricity• Crumble or break if solid

(non-malleable/ductile)

NeonHelium

Iodine Chlorine Carbon Sulfur

Properties of Elements on the Periodic Table An element’s physical and chemical properties

can be predicted from its location in the periodic table Example: Sodium is more reactive than Aluminum

Reactivity in metals decreases as you go from left to right.

For nonmetals, the opposite is true. Nonmetals in Groups 13 through 17 become more reactive from left to right. Group 18, the Noble Gases, are an exception.

• Metals: Orange

• Metalloids: Yellow

• Nonmetals: Purple

• Lanthanide & Actinides: Green

Pre-APPeriodic Trends

• Atomic Radius – related to the atom’s volume.

− Period – atomic radius decreases as you go from left to right

− Group – atomic radius increases as you go down a group

Pre-APPeriodic Trends

• Electronegativity – the atoms “desire” to grab another atom’s electrons.

− Period – electronegativity increases as you go from left to right

− Group – electronegativity decreases as you go down a group

Pre-APPeriodic Trends

• Ionization Energy – amount of energy needed to remove the outermost electron. Closely related to electronegativity.

− Period – Ionization energy increases as you go from left to right

− Group – Ionization energy decreases as you go down a group

Pre-APPeriodic Trends

• Reactivity – how likely or how vigorously an atom is to react with another substance.• Non-Metals

− Period - reactivity increases as you go from left to right, except for Group 18

− Group – reactivity decreases as you go down the group

• Metals − Period – reactivity decreases as you go from left to

right− Group – reactivity increases as you go down a group

Pre-APPeriodic Trends

• Melting Point• Metals – the melting point for metals

decreases as you go down a group• Non-Metals – the melting point for

non-metals increases as you go down a group

Hydrogen Belongs to a family of its own.

Diatomic, reactive gas.

Was involved in the explosion of the Hindenburg aircraft.

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

1 valence electron

Alkaline Earth Metals Second column on the periodic

table. (Group 2)

Reactive metals

Always combined with nonmetals in nature.

Several are important mineral nutrients (Mg and Ca)

2 valence electrons

Transition Metals

Elements in groups 3-12

Less reactive harder metals

Includes metals used in jewelry and construction.

Boron Family

Elements in group 13

Aluminum metal was once rare and expensive, not a “disposable metal.”

Carbon Family Elements in group 14

Contains elements important to life and computers.

Carbon is the basis for an entire branch of chemistry.

Silicon and Germanium are important semiconductors.

Nitrogen Family Elements in group 15

Nitrogen makes up over ¾ of Earth’s atmosphere.

Nitrogen and phosphorus are both important in living things.

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

The red stuff on the tip of matches is phosphorus.

Oxygen Family Elements in group 16

Oxygen is necessary for respiration.

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 (STABLE), monatomic gases

Used in lighted “neon” signs

Used in blimps to fix the Hindenburg problem.

Have a full valence shell.

One of two rows that “sits off” to the bottom of the periodic table

Reactive

Fairly soft metals

Lanthanide Series

Also towards bottom of periodic table

All are radioactive, some are not found in nature

Some with higher atomic numbers have only been made in labs

Actinide Series