The position of an element in the Periodic Table is determined by
- A. Its atomic radius.
- B. Its density.
- C. Its relative atomic mass.
- D. The number of protons in its atom.
- E. The number of neutrons in its atoms.
Correct Answer: Option D
Explanation
The atomic number, which is essentially the number of protons in the nucleus of an atom of that element, largely determines the position of an element in the Periodic Table. Each element has its atomic number, which signifies its unique identity.
Atoms are made up of protons, neutrons, and electrons at their most fundamental level. In the nucleus, protons are positively charged particles. The number of protons determines atomic identity; for instance, an atom with one proton is hydrogen, while an atom with two protons is helium.
The Periodic Table is a methodical arrangement of the elements in ascending order of atomic number. It is organized into periods and groups in rows and columns, respectively. Along a period, the atomic number increases from left to right, and elements within a group have similar chemical properties due to having the same number of valence electrons responsible for chemical bonding.
The Periodic Table is segmented into blocks (s, p, d, and f) based on the electron configuration of the elements, further illustrating the connection between atomic structure and the table’s organization. Hydrogen and helium are included in Groups 1 and 2 of the “s block” The “p block” consists of Groups 13 through 18. The “d block” is composed of transition metals, whereas the “f block” contains lanthanides and actinides.
Hydrogen (1 proton) begins the first period, followed by helium (2 protons). Beginning with the second period, the placement of elements is determined by their atomic numbers and electron configurations. Lithium (with three protons) begins the second period with one electron in its outermost shell, followed by Beryllium (with four protons) with two outer electrons, etc.
Groups denote elements with the same number of outer shell electrons. For instance, group 1 elements (alkali metals) all have one electron in their outermost shell, contributing to their similar reactivity. Thus, an atom’s atomic number (protons) identifies the element and determines its placement on the Periodic Table and chemistry.