Year 8 Science · Unit 2 · Lesson 11

The Periodic Table

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Learning Goals

Order the steps

Number the steps from 1 to 6 to show the correct order for reading information from an element tile. Step 1 = what you do first.

OrderStep
Calculate the number of neutrons (mass number − atomic number)
Read the symbol (1 or 2 letters, first letter always capital)
Find the element tile on the periodic table
Read the mass number from the tile
Find the atomic number (the smaller number, usually shown at the top)
Identify the element's full name

Compare two

Complete the table to compare Mendeleev's original periodic table with the modern periodic table. Fill in both columns for each feature.

Feature Mendeleev's table (1869) Modern periodic table
Ordered by
Number of elements known
Had gaps for missing elements?
Can it predict new elements?
Most useful for

1. Element X has atomic number 15 and mass number 31. Calculate its neutron count, and state which period and group it belongs to (phosphorus is in Period 3, Group 15).

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2. Sodium (Na) and potassium (K) are both in Group 1 of the periodic table. Using what you know about groups, predict one property they are likely to share. Explain your reasoning.

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Wrap Up

In one sentence, what was the main idea of this lesson?