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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.
Elements
The elements, alone or in combinations, make up our bodies, our world, our sun, and in fact, the entire universe.
The “Father” of the Periodic Table
Dimitri Mendeleev was the first person to publish an organization of the elements.
Mendeleev organized the known elements in order of their atomic mass.
He correctly predicted the existence of unknown elements (Si, Al, Ga)
Dimitri Mendeleev 1834-1907
Periodic Table
The modern periodic table organizes the elements according to their atomic number.
Physical and chemical properties of an element can be predicted simply by its position in the periodic table.
The atomic number is determined by the number of protons an element has
No two elements have the same atomic number
Symbols
All elements have their own unique symbol.
It can consist of a single capital letter, or a capital letter and one or two lower case letters.
C Carbon
CuCopper
Common Elements and Symbols
What are the symbols for the following elements?
1. sodium 2. silver
3. beryllium 4. iron
5. lead 6. hydrogen
7. oxygen 8. gold
9. copper 10. phosphorus
Common Elements and Symbols
What are the symbols for the following elements?
1. sodium Na 2. silver Ag
3. beryllium Be 4. iron Fe
5. lead Pb 6. hydrogen H
7. oxygen O 8. gold Au
9. copper Cu 10. phosphorus P
Common Elements and Symbols
What are the names of the elements with the following symbols?
1. K 2. N
3. Li 4. Ne
5. Ca 6. C
7. Ar 8. Sn
9. Zn 10. Cl
Common Elements and Symbols
What are the names of the elements with the following symbols?
1. K potassium 2. N nitrogen
3. Li lithium 4. Ne neon
5. Ca calcium 6. C carbon
7. Ar argon 8. Sn tin
9. Zn zinc 10. Cl chlorine
Structure of the Periodic Table
There are three types of elements on the periodic table: metals, non-metals and metalloids
Metals are found on the left side of the zig-zag line.
Non-metals are found on the right side of the zig-zag line
Metalloids are found on the zig-zag line
a) sodium b) nitrogen
c) bromine d) calcium
e) xenon f) zinc
Which of the following are metals?
a) sodium d) calcium f) zinc
Families or groups on the Periodic Table
Elements that are in the same family or group have similar physical and chemical properties.
It was these properties that Mendeleev used to create the table.
Hydrogen
Hydrogen sits at the top of Group 1, but it is not a member of that family.
Hydrogen is in a class of its own.
It is a non-metal, not a metal.
Group 1 – Alkali Metals
The alkali family is found in the first column.
They are shiny, soft metals that are highly reactive.
Alkali Metals
Alkali metals react violently with water and air.
They are never found as free elements in nature, they are always in compounds with another element.
Group 2 – Alkaline Earth Metals
They are rarely found as single elements in nature.
Alkaline earth metals include magnesium and calcium.
Groups 3-12: Transition Metals
Transition Elements are probably the metals you are most familiar with: copper, tin, zinc, iron, nickel, gold, and silver.
They are good conductors of heat and electricity.
Group 17 – Halogen Family
Halogens are the most reactive non-metals.
They are never found free in nature.
They react easily with alkali metals.
Group 18 – Noble Gases
Noble Gases are colorless gases that are extremely un-reactive.
Because they do not form compounds with other elements, they are called inert.
All the noble gases are found in small amounts in the Earth's atmosphere.
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