An element with an atomic number of 19 would be expected to be located in the periodic table's fourth period (row) and the third group (column).
The periodic table is organized based on the atomic number, which represents the number of protons in an atom's nucleus. In this case, the atomic number is 19, indicating that the element has 19 protons.
The periodic table's periods represent the principal energy levels or electron shells of the atoms. Since the atomic number is 19, the element would belong to the fourth period because the fourth period includes elements with atomic numbers 19 to 36.
The groups in the periodic table represent elements with similar chemical properties due to their similar electron configurations. The element with an atomic number of 19 would be located in the third group because it has three valence electrons in its outermost energy level. Elements in the same group tend to exhibit similar chemical behavior because they have the same number of valence electrons, which determines their reactivity and bonding patterns.
To be more specific, an element with atomic number 19 is potassium (K). Therefore, you would expect to find potassium (K) in the fourth period and the third group of the periodic table.