Give the symbol of the element that meets the following condition: has one electron in the 3s sublevel (Express your answer as a chemical symbol.) Solution ANSWER : Given information : Element have one electron in the 3s sublevel. Now, This data represent that, element is belong to third period of periodic table because it principal quantum number is 3. And it belongs to S-block element in periodic table. Since, only one electon is present in sublevel. That means the data represents the first element of third period in s-block that is sodium (Na). Hence, Na has one electron in the 3s sublevel. .