Question

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Answer 1

Answer:

Na (Sodium), Mg (Magnesium) and Al(Aluminium) are metals. Si (Silicon) is a metalloid. P (Phosphorus), S (Sulphur) and Cl (Chlorine) are non-metals. As we go from left to right across the third period, metallic character decreases and non-metallic character increases.

Explanation:

first question answer

Answer 2

Answer:

1)Metals:Sodium(Na) , Magnesium(Mg), Aluminium(Al)                          

 Non Metals:Phosporus (P), Sulphur(S),  Chlorine(Cl)        

2)Neon, Fluorine, Oxygen, Nitrogen, Carbon, boron, Berillium, Lithium

3)Lithium, Berillium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon

Explanation:

First twenty elements of periodic table

H                                 He

Li   Be  B  C  N  O  F  Ne

Na Mg Al  Si P  S  Cl  Ar

K   Ca

*Rows are known as periods and Columns are known as groups.

*Imagine there is an invisible staircase along (B) Boron and Silicon.

*Elements just to the right of the staircase exhibit properties of both metals and nonmetals and are termed metalloids or semimetals (Boron,Silicon). Elements to the far right of the periodic table are nonmetals (C,P..). Elements to the left side are metals(Be,Al...).

*Last group elements are noble gases.

*The exception is hydrogen (H). At ordinary temperatures and pressures, hydrogen behaves as a nonmetal.

Qs 1) Third period

Na Mg Al  Si P  S  Cl  Ar

*Elements to right side of Silicon are non metals.

* Elements to the left side of Silicon are metals.

*Last element (Belongs to last group) Argon is a noble gas

Metals                        Non Metals

Sodium(Na)                Phosporus (P)

Magnesium(Mg)         Sulphur(S)

Aluminium(Al)             Chlorine(Cl)

Qs 2) second period

Li   Be  B  C  N  O  F  Ne

Tendency to lose electrons - first ionisation energy

*Across a period from left to right, the ionisation energy increases.

*Since noble gases have completely filled valence shells that are highly stable, they have highest first ionisation energy.

*Thus Helium has the least tendency to lose electrons as it has highest first ionisation energy.

So, if we want to write the ascending order of elements that have the tendency to lose electrons, we have to write starting from a noble gase to alkali element.

Answer: Neon, Fluorine, Oxygen, Nitrogen, Carbon, boron, Berillium, Lithium

Qs 3) second period

Li   Be  B  C  N  O  F  Ne

*The radii generally decrease rightward along each period (row) of the table, from the alkali metals to the noble gases; and increase down each group (column)

So, decreasing order is same as the order in periods.

Ans: Lithium, Berillium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon