Trends in Atomic Radius
* Across a Period (Left to Right): Atomic radius generally *decreases* as you move from left to right across a period. This is because the number of protons in the nucleus increases, which attracts the electrons more strongly, pulling them closer to the nucleus.
* Down a Group (Top to Bottom): Atomic radius generally *increases* as you move down a group. This is because you're adding electron shells, making the atom larger.
To determine the order of decreasing atomic radius, you need to consider both trends:
1. Identify the elements: You haven't provided a list of elements, so I can't give you a specific answer.
2. Locate them on the periodic table: Find the positions of the elements on the periodic table.
3. Apply the trends:
* Elements in the same period but further to the right will have smaller atomic radii.
* Elements in the same group but lower down will have larger atomic radii.
Example
Let's say you have the elements: Li, Na, K, F, Cl.
1. Location: Li, Na, and K are in Group 1 (alkali metals). F and Cl are in Group 17 (halogens).
2. Trends:
* Na and K are larger than Li because they are lower in the group.
* Cl is larger than F because it is lower in the group.
* Li, Na, and K are all larger than F and Cl because they are further to the left on the periodic table.
Therefore, the order of decreasing atomic radius would be: K > Na > Li > Cl > F.
Let me know the specific elements you're working with, and I can help you determine the correct order!
