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Grade 10 Science · Classification of Elements
Modern Periodic Table
Moseley, 1913 · 7 periods, 18 groups · s, p, d, f blocks
By the end you can
⚖️
Explain why atomic weight failed
📜
State the modern periodic law
🧭
Read periods and groups
👨👩👧
Locate the element families
🧩
Point out the s, p, d, f blocks
📍
Place an element from its atomic number
Two bases for one table
⚖️Mendeleev: atomic weight
Carbon has three atomic weights
No separate space for isotopes
Some properties unexplained
VS
🔢Moseley: atomic number
Carbon has one atomic number: 6
Isotopes rightly share one box
Properties repeat regularly
Presenter notes: Today we study the modern periodic table, in which elements are arranged by atomic number.