The Main Groups
in the Modern Periodic Table
in the Modern Periodic Table
Lesson objectives
- At the end of this lesson, The student should be able to :
1-Determine the valency of alkali metals.
2-Describe the behaviours of alkali elements in the chemical reactions.
3-Deduce the general properties of alkali metals.
4- Determine the valency of alkali Earth metals.
5-Describe the behavior of alkali Earth metals in chemical reactions.
6-Deduce the general properties of alkali Earth metals.
7-Compare between the properties of alkali metals and alkali Earth metals.
8- Define halogen group.
9- Deduce the general properties of halogens.
11-Appreciate the importance of alkali metals and alkali Earth metals in our life.
12- Describe the properties of elements and their uses.
13-Appreciate the role of scientists and their efforts in studying elements and their uses in our life
Some of the main groups in the periodic table are characterized by names as explained in this lesson:
1- Alkali metals group (Group 1A)
1-They are mono-valent elements because their outermost shells contain (1) electron.
2-They tend to lose their valency electron forming positive ions that carries one positive ion.
3-They are chemically active elements so they are kept under kerosene or paraffin to prevent their reaction with the moist air.
4-Their chemical activity increases by the increase of atomic size.
Cesium (Cs) is considered as the most active metal in general.
5-They are good conductors of heat and electricity.
6-Most of them have low density .
* For more information about alkali metals group, please visit these sites:
* This sites for chemical properties of group (1A)
2- Alkaline Earth metals (Group 2A)
1-They are divalent elements because they contain 2 electrons in their outermost (valency) shells.
2- They tend to lose their valency electrons forming positive ions that carry two positive charges.
3-They are less active than alkali metals.
4-Their chemical activity increases by the increase of the atomic size because the loss of the valency electrons becomes easier
5- They are good conductors of heat and electricity.
6- They have more density than alkali metals.
* For more information about alkali earth metals group, please visit these sites:
* This sites for chemical properties of group (2A)
3- Halogens group (7A)
1-They are mono-valent nonmetals
2-They exist as diatomic molecules F2 , Cl2 ,
3- They are chemically active elements, so they do not exist individually in nature but they exist in chemical compounds ,except astatine which is prepared artificially.
4- Each element in the group replaces the element below it in their solutions.
Cl2 + 2KBr 2KCl + Br2
Clorine Potassium bromide Potassium chloride Bromine
Br2 + 2KI 2KBr + I2
5-Bromine
Potassium Iodine Potassium bromide Iodine
6- The physical state is graduated from the gaseous state (Flourine , Chlorine)
to the liquid state (Bromine) to solid
state (Iodine).
* For more information about halogens group, please visit these sites:
* This sites for chemical properties of group (7A)
The properties of elements and their uses
1- Sodium is used in liquid state as it is a good conductor of heat , it is used also in transferring heat
from inside the nuclear reactor to outside to obtain vapor energy required to generate electricity core of
nuclear reactor
2-Silicon slides are used in the manufacture of computers because they are semi conductor which their
conductivity of electricity depends on the temperature.
2-Liquified nitrogen is used in preservation of the cornea of the eye because it has a low boiling point electronic slide
3- The radioactive cobalt 60 is used in food preservation
because gamma rays which come out from it prevent
the reproduction of microbial cells without an effect on
human.
please visit this video because it shows this lesson in detail:
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