Increases order of atomic radii is

Options

A. `Ca lt Na lt Mg`
B. `Mg lt Ca lt Na`
C. `Mg lt Na lt Ca`
D. `Na lt Mg lt Ca`

Answer

To determine the increasing order of atomic radii among the given elements, we will follow these steps:

### Step 1: Identify the Elements
First, we need to identify the elements for which we are determining the atomic radii. For this example, let's consider the elements Sodium (Na), Magnesium (Mg), and Calcium (Ca).

### Step 2: Locate Elements in the Periodic Table
Next, we will locate these elements in the periodic table:
- Sodium (Na) is in Group 1, Period 3.
- Magnesium (Mg) is in Group 2, Period 3.
- Calcium (Ca) is in Group 2, Period 4.

### Step 3: Understand Atomic Radius Trends
Now, we need to understand the trends in atomic radii:
- Atomic radius decreases across a period from left to right due to increasing nuclear charge, which pulls the electrons closer to the nucleus.
- Atomic radius increases down a group due to the addition of electron shells.

### Step 4: Compare Atomic Radii
Using the trends:
- Sodium (Na) is in Period 3 and has a larger atomic radius than Magnesium (Mg), which is also in Period 3 but further to the right.
- Calcium (Ca) is in Period 4, which means it has an additional electron shell compared to both Sodium and Magnesium, resulting in a larger atomic radius.

### Step 5: Establish the Increasing Order
Based on the above comparisons:
- Magnesium (Mg) has the smallest atomic radius.
- Sodium (Na) has a larger atomic radius than Magnesium.
- Calcium (Ca) has the largest atomic radius.

Thus, the increasing order of atomic radii is:
**Mg < Na < Ca**

### Final Answer
The increasing order of atomic radii is:
**Magnesium (Mg) < Sodium (Na) < Calcium (Ca)**

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