2.3.2Additional lessons
s and p Block Elements — IB Chemistry HL Revision Notes & Topical Questions
5 min read 5 parts Lesson 43 of 172
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Section 1 of 5Blocks of the Periodic Table
The block of an element tells you which subshell holds its highest-energy electrons.
s block
- s block Groups 1 and 2, where the outermost electrons occupy an s subshell.
p block
- p block Groups 13 to 18, where the outermost electrons are filling a p subshell.
d block
- d block The transition metals between groups 2 and 13.
Hydrogen and helium
- Hydrogen and helium Hydrogen sits in the s block and helium also has outer electrons in the s subshell.
Section 2 of 5Metallic Character
Metallic Character
s block
- s block All s block elements apart from hydrogen and helium are metals with low ionisation energies.
p block metals
- p block metals Aluminium, tin and lead are metals in the p block.
Metalloids
- Metalloids Boron, silicon, germanium, arsenic and antimony have properties between metals and non-metals.
Non-metals
- Non-metals Carbon, nitrogen, oxygen, phosphorus, sulfur and the halogens are non-metals.
Section 3 of 5Period 3 Melting Points
1
Sodium, magnesium and aluminium have metallic bonding that strengthens as ion charge rises, so their melting points increase.
2
Silicon has a giant covalent structure and melts near 1410 °C, the highest in the period.
3
Phosphorus, sulfur and chlorine form small molecules held by weak London forces and melt at low temperatures.
4
Argon exists as single atoms with very weak forces and melts at about −189 °C.
| Element | Structure | Melting point / °C |
|---|---|---|
| Na | Metallic | 98 |
| Al | Metallic | 660 |
| Si | Giant covalent | 1410 |
| S | Simple molecular | about 115 |
| Cl | Simple molecular | −101 |
Section 4 of 5Physical Property Patterns
Conductivity
- Conductivity Metals conduct well, silicon is a semiconductor and most non-metals are insulators.
Down groups
- Down groups Metallic character increases down both s and p groups.
Across periods
- Across periods Metallic character decreases from left to right.
Section 5 of 5Exam Checklist & Tips
2.3.2 – Key Points for the Exam
- s block Elements whose valence electrons are in an s subshell.
- p block Elements whose valence electrons are filling a p subshell.
- Metalloid An element with intermediate properties between a metal and a non-metal.
- Semiconductor A material that conducts only slightly, and better when warmed.
Common Mistakes
- Assuming every element in the p block is a non-metal.
- Explaining the melting point of silicon with metallic bonding.
- Saying sulfur has a high melting point because S–S bonds break; only intermolecular forces do.
- Giving the wrong block for helium.
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