Choose and then fill in the blank with the element that has the higher first ionization energyCa or Sr

To determine which element, Ca or Sr, has the higher first ionization energy, we need to compare their positions on the periodic table.

1. Locate Ca and Sr on the periodic table. Ca is located in the second period, while Sr is located in the third period.

2. The first ionization energy refers to the energy required to remove one electron from an atom in its gaseous state. Generally, ionization energy increases from left to right across a period and decreases from top to bottom within a group on the periodic table.

3. Since Ca is located to the left of Sr on the periodic table, it is in the same period but to the left of Sr. Therefore, Ca has a lower atomic number and a smaller atomic radius compared to Sr.

4. Based on the trend mentioned earlier, we can conclude that Ca has a higher first ionization energy than Sr. This is because Ca has a smaller atomic radius, which means that the outermost electron is held more tightly by the nucleus and requires more energy to remove.

Therefore, the element with the higher first ionization energy is Ca.