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Question
State the number of elements in periods 1, Periods 2, and Period 3 of the periodic table. Name them.
Solution
Period 1 has two elements: Hydrogen (H) and Helium (He).
Period 2 has 8 elements: Lithium (Li), Beryllium (Be), Boron (B), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F), and Neon (Ne).
Period 3 has 8 elements: Sodium (Na), Magnesium (Mg), Aluminium (Al), Silicon (Si), Phosphorus (P), Sulphur (S), Chlorine (Cl), and Argon (Ar).
RELATED QUESTIONS
How does the valency of elements vary in going down a group of the periodic table?
Name the element which is in seventeenth group and second period.
The atomic numbers of three elements A, B and C are given below:
| Element | Atomic number |
| A | 5 |
| B | 7 |
| C | 10 |
(i) Which element belongs to group 18?
(ii) Which element belongs to group 15?
(iii) Which element belongs to group 13?
(iv) To which period/periods do these elements belong?
Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element. 
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The following questions refer to the Periodic Table.
What is the common feature of the electronic configurations of the elements in group 7?
With reference to the variation of properties in the Periodic table, which of the following is generally true?
Atomic numbers of elements A, B, C, D, E, F are 8, 7, 11, 12, 13 and 9 respectively. State the type of ions they form.
The position of elements A, B, C, D and E in the periodic table are shown below:
|
Group 1 |
Group 2 |
Group 17 |
Group 18 |
|
|
|
|
D |
|
|
B |
C |
|
|
A |
|
|
E |
Which type of ion will be formed by elements A, B, and C.
An element belongs to the third period and Group IIIA (13) of the periodic table. State: if it is a metal or non-metal?
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
