The periodic table in long form is divided into 4 blocks: S-block elements, P-block. elements, d-block elements, and F-block elements.
Modern periodic table
The elements are arranged in ascending order of their atomic numbers, forming a table of 18 vertical columns and 7 horizontal periods. To indicate the type of element: S, P other than group zero is a representative or main group element, group zero is a noble gas, d is a major transition element, and f is an internal transition element.
To indicate the position of an element in the periodic table, the number of periods is the highest principal quantum number in the electron configuration (period number = number of last S), and the group number is the number of valence electrons. (electrons at the outer energy level).
All elements in group VII-A are called halogens. The electronic configuration of their outer sublevel is nP 5; they are diatomic and monovalent. The seven nonmetallic elements are diatomic molecules at room temperature (H 2, N 2, O 2, F 2, Cl 2, Br 2, and I 2 ).
The elements in group zero are called noble gases ( 2 He, 10 Ne, 18 Ar, 36 Kr, 54 Xe, 86 Rn). They are monatomic, and the electron configuration of the outer sublevel in a noble gas is nP 6, except for 2. He (1S² ), the maximum number of electrons that can accept sublevels is S 2, P 6, d 10, F 14, the sequence of energy levels are:
1S <2S <2P <3S <3P <4S <3d <4P <5S <4d <5P <6S <4F <5d <6P <7S <5F <6d <7P
The electronic configuration becomes more stable when the last sublevel is filled with electrons as S 2 P 6 d 10 F 14, the last sublevel is half filled with electrons as P 3 d 5 F 7, and the last sublevel is empty as d 0 F 0 . Hund’s Rule states that At a given sublevel, no electron sharing occurs until each orbital contains one electron.
Electrons first occupy a lower energy sublevel and then a higher energy one. All elements in one group are similar in properties; nP 6 is the zero group, d 6, d 7, and d 8 are called group VIII, and d 9 is the group. IB, d 10 is called group II-B. The detailed periodic table is divided into four blocks:
S-shaped elements
S-block elements (nS 1 → 2 ) are located in the table’s left block; the outermost electrons occupy the S sublevel. It consists of two elements, IA and II-A since the S sublevel consists of a single orbit filled with 2 electrons. The electronic configuration of group IA is nS¹ and group II-A is nS², where n is the external energy level and the period number simultaneously.
P-block elements
P-block elements (nS 2, nP 1 → 6 ) are located in the right block of the table; the most distant electrons occupy the p-sublevel. These are six groups (III-A, IV-A, VA, VI-A, VII-A and the zero group of noble gases since the P sublevel consists of 3 orbitals filled with 6 electrons.
D-block elements
D-block elements [nS 2, (n − 1) d 1 → 10 ]: (Primary transition elements) are elements in which the d sublevel is sequentially filled with increasing atomic number. They lie in 10 vertical columns since the d sublevel has 5 orbitals filled with 10 electrons. The ten vertical bars are represented by 8 groups (seven of which are Group B), and the remaining three are Group VIII. They are divided into 4 series:
- The 1st series of transitions includes elements in which the 3d sublevel is sequentially filled, consists of 10 elements, is in the 4th period, begins with scandium 21 Sc (3d¹), and ends with zinc 30 Zn (3d 10 ).
- The 2nd series of transitions includes elements in which the 4d sublevel is sequentially filled, consists of 10 elements, is in the 5th period, begins with yttrium 39 Y (4d¹), and ends with cadmium 48 Cd (4d 10 ).
- The 3rd series of transitions includes elements in which sublevel 5d is sequentially filled. It consists of 10 elements. She is in the 6th period. It starts with lanthanum 57 La (5d¹) and ends with mercury 80 Hg (5d 10 ).
- The 4th series of transitions includes elements in which sublevel 6d is sequentially filled, consists of 10 elements, and is placed in the 7th period.
Group VIII does not belong to group B due to the absence of elements with similar properties in the main group. Group II-B elements are called post-transition elements.
f-block elements
F-block elements (intrinsic transition elements) are elements in which the f sublevel is sequentially filled with increasing atomic numbers and divided into two series: lanthanides and actinides.
Ionization energy
Ionization energy is the amount of energy required to completely remove the most weakly bound electron from an isolated gaseous atom (endothermic); one, two, three, or more electrons can be removed from an atom, so there is a First, Second, and Third ionization potential.
The first ionization potential is the energy required to convert an atom into an ion with one positive charge.
M → M + + e¯
The second ionization potential is the energy required to convert an ion with one positive charge to an ion with two positive charges.
M + → M +2 + e¯
The third ionization potential is the energy required to convert an ion with two positive charges to an ion with three positive charges.
M +2 → M +3 + e ¯
For the same element 3rd IP > 2nd IP > 1st IP for the same element due to the positive charge effect increases, group 2A nS² full (stable) high IP, group 5A nP 3 half filled stable high IP, Group Zero nP 6 is fully filled (stable) high IP.
Oxidation numbers
The oxidation number is the positive or negative charge of an ion or atom in a compound as an ionic or covalent compound.
- Neutral molecule: sum of oxidation states = zero
- Charged molecule (radical): sum of oxidation states = charge transferred