Rank the elements Ca, As, K, Br from highest to lowest first ionization energy. (Type your answer using the format W>X>Y>Z.)
Would the answer be: K>Ca>As>B
Let's compare K with Ca.
K has 19+ charges and 1 outside electron.
Ca has 20+ charges and 2 outside electrons. So it should be harder to pull an electron from Ca than K and first IP should be higher for Ca than K. right?
To rank the elements Ca, As, K, and Br from highest to lowest first ionization energy, we need to compare the trends in the periodic table.
The first ionization energy generally increases from left to right across a period and decreases from top to bottom within a group in the periodic table.
Let's analyze the elements one by one:
1. K (Potassium): Located in Group 1 (Alkali Metals) and Period 4.
- It has a lower first ionization energy compared to other elements because it has a relatively large atomic radius and its valence electron is further from the nucleus.
- Therefore, the first ionization energy of K is the lowest among the given elements.
2. Ca (Calcium): Located in Group 2 (Alkaline Earth Metals) and Period 4.
- It has a higher first ionization energy compared to K because it has a smaller atomic radius and its valence electron is closer to the nucleus.
- Therefore, the first ionization energy of Ca is higher than that of K.
3. As (Arsenic): Located in Group 15 (Pnictogens) and Period 4.
- It has a higher first ionization energy compared to Ca as it is located further to the right on the periodic table.
- Therefore, the first ionization energy of As is higher than that of Ca.
4. Br (Bromine): Located in Group 17 (Halogens) and Period 4.
- It has the highest first ionization energy among the given elements.
- Bromine has a smaller atomic radius, and its valence shell electron is closer to the nucleus compared to As.
- Therefore, the first ionization energy of Br is the highest among the given elements.
Based on the explanations above, the correct ranking from highest to lowest first ionization energy is: Br > As > Ca > K.