It’s the periodic table again. Similar to Part 1, this Part 2 of the “STPM Chemistry Form 6 notes on The Periodic Table” from Berry Berry Easy also only deals with the simpler aspects of the periodic table. No headaches expected from students. However, you’ll need to fully understand the concepts presented below and master the s,p,d,f blocks elements before you move on to the more difficult aspects of the periodic table.
It is also important that you familiarise yourself with the notions of atomic radius, ionic radius, electronegativity and the ionisation energy of an atom. It’ll come useful.
STPM Chemistry Form 6 Notes – Terminology and Concepts: The Periodic Table (Part 2)
The Modern Periodic Table
The modern Periodic Table is constructed on the basis of the proton (atomic) numbers of the elements and their electronic configuration
A) The short periods
- Period 1 – the 1s orbital is being filled.
- Period 2 – the 2s orbital is filled first, followed by the 2p orbital in the outermost shell (8 elements).
- Period 3 – the 3s orbital is filled first, followed by the 3p orbital in the outermost shell (8 elements).
B) The long periods
- Period 4 – the 4s, 3d and 4p orbitals are involved in the outermost shell (18 elements).
- Period 5 – the 5s, 4d and 5p orbitals are involved in the outermost shell (18 elements).
- Period 6 – the 6s, 4f, 5d and 6p orbitals are involved in the outermost shell (32 elements) and one series known as the lanthanides.
- Period 7 – the 7s, 5f, 6d and 7p orbitals are involved in the outermost shell (increasing due to the discovery of new elements) and one series known as the actinides.
C) The groups in the periodic table
The s-block elements:
- Group 1 – general electronic configuration ns1.
- Group 2 – ns2.
The p-block elements
- Group 13 – ns2np1.
- Group 14 – ns2 np2.
- Group 15 – ns2 np3.
- Group 16 – ns2 np4.
- Group 17 – ns2 np5.
- Group 18 – ns2 np6.
The d-block elements
- Between Group 2 and Group 13 that the d orbitals are partially occupied.
The f-block elements
- Lanthanides (15 elements) – 4f orbitals are partially filled and must have a 6s2.
- Actinides (15 elements) – 5f orbitals are partially filled and must have a 7s2. All actinide elements are radioactive.
- Atomic Radius – half the distance between the nuclei of the two closest atoms in an element.
- Atomic Radii – decrease across a period from left to right in the periodic table & increase down a group in the periodic table.
- Ionic Radius – measure of the size of an atoms ion in a crystal lattice. Cation is smaller than the corresponding metal atom and anion is larger than the corresponding nonmetal atom.
- Electronegativity – measures the ability of an atom to attract to itself the electron pair forming a covalent bond. The greater the electronegativity of an atom, the greater the atom attraction for electrons.
- Ionisation Energy of an Atom – measures of its tendency to lose electrons. The larger the ionisation energy, the more difficult it is to remove an electron.
Before we end, ask yourself too, “Why the the atomic radii decrease across a period and increase down a group in the periodic table?”. If you cannot answer it, the answers will be revealed in the Part 3.