In the periodic table, there is a size trend.
The trend occurs horizontally and vertically on the table.
- From right to left, the atomic radius gets larger.
- From top to bottom, the atomic radius gets larger.
The reasoning for this is the additional energy levels and electrons being added as you go from right to left or top to bottom.
We can see that Magnesium is higher and more right in the periodic table than sodium and calcium.
Thus, Magnesium has a smaller atomic radius than both sodium and calcium
The given question is incomplete. The complete question is :
Which of the following Group 17 elements is the least reactive
a) Flourine
b) Chlorine
c) Astatine
d) Iodine
Answer: c) Astatine
Explanation:
Halogen is the name given to Group 17 family with general electronic configuration of 
which have 7 valence electrons and thus easily gain one electron to attain stable configuration.
As we move down the group from flourine to chlorine to bromine to iodine to astatine , the valence shell moves farther from nucleus and thus tendency to accept the electron decreases and thus reactivity also decreases.
Thus Astatine is the least reactive of all.
Answer:
Chlorine can be found in Period 3.
Explanation:
Periods on the periodic table are the rows (horizontal sections) that group elements together. By looking across Period 3, you will find Cl (chlorine).
Answer:
The amount of thermal energy stored in an object depends on three things.
- The mass of the object.
- The temperature of the object.
- The amount of energy that the particular material stores per degree of temperature.
