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Organization in the periodic table, abstract-stripes-gradient-black-white…
Organization in the periodic table
Mendeleev's arrangemnet
The elements were arranged by Mendeleev according to the increasing atomic weight of each but also in a way in which the similar element's properties shared a vertical column.
He called the vertical column "groups" and the horizontal rows "periods."
He also predicted the properties of the missing elements such as: density, atomic weight, color and melting point.
His periodic table was quickly approved by scientists, however the table has been modified. New dicoveries led scientist to realize that the elements must be arranged by proton number, and that table is the same one the we use nowdays.
Groups
Elements with similar properties share a column called groups.
There are 8 groups of elements.
First column: Group I
Second column: Group II
And so on until: Group VII
The last column is called: Group 0 (VIII)
Some of the groups have names.
Group I: "Alkali metals" Group II: "Alkine earth metals Group VII: "The halogens"
Group 0: "Noble gases"
Between Group II and III, there is a BLOCK of elements called "Transition elements."
Group I: The Alkali metals
Consists of 5 metals
potassium
rubidium
sodium
Available for usage in schools
caesium
Lithium
They are all reactive metals
Stored under oil to prevent they coming in contact with water or air.
Properties:
Good conductors of electricity and heat
Soft metals
Low densities
Shiny surfaces
Low melting points
Burn in oxigen or air to form solid oxides
Dissolve in water to form alkali solutions as well as producing hydrogen gas.
React with halogens to form metal halides.
Group II: The alkaline earth metas:
Consists of 5 metals
Calcium
Available for usage in schools
Strontium
Magnesium
Barium
Beryllium
Properties:
Harder than elements in Group I
Silvery-grey colored, however with contact in air they form a metal oxide in its surface.
Good conductors of heat and electricity
Burn in oxygen to form solid white oxides
React in water
Group VII: The halogens
elements:
Fluorine
chlorime
bromine
iodine
Astatine
Radioactive element
Properties:
colored and darken going down the group
exist as diatomic molecules
Gradual change from a gas to a liquid to a solid as the denisty increases
Form molecular compound with non-metalic elements
React with Hydrigen to produce Hydrogen halides
React with metals to produce ionic metal halides
Group 0: The noble gases
elements:
Neon
Argon
Helium
Krypton
xenon
radon
Radioactive element
The noble gases were discovered after Mendeleev published his periodic table.
Properties:
unreactive
They exist as individual atoms
monatomic gases
colorless gases
Uses of halogens: Fluoride in toothpaste, chlorine in households to kill bacteria, iodine to photographic reproduction and bromine as a fire retardant. Neon is used to light up extensive signs and lasers.
Transition elements
Properties:
Harder and stronger than metals in groups I and II
Higher densities than elements in groups I and II
High melting points, exept mercury
Less reactive metals
Brightly colored compounds
Good conductors of heat and electricity
show catalitic activity
Don't react quickly with oxygen and water
They form simple ions with more than one oxidation state
They form complicated ions with high oxidation states
The position of hydrogen:
Hydrogen is placed by himself in the periodic table
Hydrogen's properties are unqiue
It is often shown at the top of the group I or VII
It can't fit easily into the trends in each group
Metals in the Periodic Table
The periodic table is divided into two.
Metals
They are on the left side of the line
Metalic character of the element in a group increases as you go down the group.
Electrons become easier to loose.
There is less atraction between the nucleus and the outer energy level because of the increase distance between them.
The dividing line is found beneath Boron
Those elements which lie in the dividing line are called metaloids
Non-Metals
They are located on the right side of the line
There is a gradual change in the periodic table from metal to non metals.
Periods
Horizontal rows
numbered from 1 to 7
They go down the Periodic Table
Structures
Electronic Structure
The number of electrons in the outer energy level corresponds with the number of the group in the periodic table where the element is found.
Example: Elements in the Group I, have 1 electron in their outer energy level.
Elements in Group 0 are an exeption of this rule. They have 2 or 8 electrons in their outer shells.
Outer electrons are mainly responsable for the chemical properties of the elements. Elements in the same group have similar chemical properties.
Bibliography:
Bryan Earl, Doug Wilford. (2014). Chemistry. Italy: Hobber Education. (Online chemistry book: pages 135 to 146)
(All images have the link from where I got them, you just have to click on the image.)
Metals
Non-metals
