International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is the electronic configuration of potassium?

1. 2.8.8.1

2. 2.7.8

3. 2.8.2

4. 2.8.6

The correct answer is: 2.8.8.1

The electronic configuration of potassium is denoted as 2.8.8.1, which reflects how the electrons are distributed in the atomic orbitals of the element. Potassium, with the atomic number 19, has a total of 19 electrons. In the configuration, the first number indicates that there are 2 electrons in the first shell (which can hold a maximum of 2 electrons), the second number indicates that there are 8 electrons in the second shell (which can hold up to 8 electrons), the third number represents 8 electrons in the third shell, and the last number reflects the 1 electron in the outermost shell or fourth shell. This outermost electron configuration is significant because it determines the chemical properties of potassium, including its reactivity. As potassium is an alkali metal, it readily loses that single outer electron to form a positive ion, which is a characteristic behavior of alkali metals. The other choices do not align with the actual number of electrons in potassium's shells. For instance, 2.7.8 does not account for all 19 electrons, nor does 2.8.2 or 2.8.6 accurately represent the electron distribution in potassium. This understanding of electron