1.4.1Principles of Chemistry
Periodic Table- Basics — Edexcel International GCSE Science Double Award 4SD0 - Chemistry Revision Notes & Topical Questions
5 min read 4 parts Lesson 18 of 50
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.
Part 1 of 4Layout of the Table
Elements are arranged in order of increasing atomic number, so each element has one more proton than the element before it.
Period
- Period A horizontal row showing how many electron shells an atom has, numbered 1 to 7, so period 3 atoms have three shells.
Group
- Group A vertical column showing how many electrons an atom has in its outer shell, so Group 6 atoms have six outer electrons.
Group 0
- Group 0 The final column, containing the noble gases, which have full outer shells and are numbered 0 rather than 8.
Atomic number
- Atomic number The number of protons in an atom, which is unique to each element and does not change when electrons are lost or gained.
Part 2 of 4Locating an Element
1
Find the atomic number of the element, then find that element in the table to see its position.
2
Count the number of occupied electron shells, which gives the period number; for example, chlorine has three shells and is in period 3.
3
Read the number of outer shell electrons from the group number; chlorine is in Group 7, so it has seven outer electrons.
4
Use the group and period together to predict the electron arrangement, which for chlorine is 2,8,7.
Part 3 of 4Patterns Across the Table
Patterns Across the Table
Ordering
- Ordering Elements are ordered by atomic number, which places elements with similar properties in the same vertical columns.
Similar reactions
- Similar reactions Elements in the same group react in similar ways because they have the same number of outer shell electrons.
Metals and non-metals
- Metals and non-metals Metals lie to the left of a zig-zag line and non-metals lie to the right, with a few elements on the line called metalloids.
Period numbers
- Period numbers Group numbers are printed on the exam table but period numbers are usually not, so writing them in first saves time.
Part 4 of 4Exam Checklist & Tips
1.4.1 – Key Points for the Exam
- Period A horizontal row of the periodic table, showing the number of electron shells in each atom.
- Group A vertical column of the periodic table, showing the number of outer shell electrons.
- Atomic number The number of protons in the nucleus of an atom.
- Group 0 The noble gases, which have full outer shells.
- Metalloid An element whose properties lie between those of metals and non-metals, found along the zig-zag line.
Common Mistakes
- Mixing up period and groupperiods are rows showing shell numbers, and groups are columns showing outer electrons.
- Using the mass number to place an element in the table; the atomic number determines its position.
- Numbering the noble gas column as Group 8 rather than Group 0.
- Thinking the atomic number changes when an atom loses electrons in a reaction;
- only the number of electrons changes.
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