1. Section 2: Classification of the Elements
Elements are organized into different blocks in the periodic table according to their electron configurations. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions
Why do elements in the same group have similar properties?
Based on their electron configurations, what are the four blocks of the periodic table?
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Classification of the Elements

3. Vocabulary Review valence electron Classification of the Elements
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4. Organizing the Elements by Electron Configuration
Recall electrons in the highest principal energy level are called valence electrons. All group 1 elements have one valence electron.
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Classification of the Elements

5. Organizing the Elements by Electron Configuration
Group 2 elements have two valence electrons. The number of valence electrons for elements in groups 13–18 is ten less than their group number. The energy level of an element’s valence electrons indicates the period on the periodic table in which it is found.
Classification of the Elements
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6. The s-, p-, d-, and f-Block Elements
The shape of the periodic table becomes clear if it is divided into blocks representing the atom’s energy sublevel being filled with valence electrons.
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Classification of the Elements

7. The s-, p-, d-, and f-Block Elements
s-block elements consist of group 1 and 2, and the element helium.
Group 1 elements have a partially filled s orbital with one electron.
Group 2 elements have a completely filled s orbital with two electrons.
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Classification of the Elements

8. The s-, p-, d-, and f-Block Elements
Groups 13–18 fill the p orbitals. In group 18, both the s and p orbitals of the period’s principal energy level are completely filled.
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Classification of the Elements

9. Interactive Table – Noble Gas Electron Configuration
Concepts in Motion
Classification of the Elements
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10. The s-, p-, d-, and f-Block Elements
The d-block contains the transition metals and is the largest block.
There are exceptions, but d-block elements usually have filled outermost s orbitals, and filled or partially filled d orbitals.
The five d orbitals can hold 10 electrons, so the d-block spans ten groups on the periodic table.
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Classification of the Elements

11. The s-, p-, d-, and f-Block Elements
The f-block contains the inner transition metals.
f-block elements have filled or partially filled outermost s orbitals and filled or partially filled 4f and 5f orbitals.
The 7f orbitals hold 14 electrons, and the inner transition metals span 14 groups.
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Classification of the Elements

12. Electron Configuration and the Periodic Table
SOLVE FOR THE UNKNOWN
For representative elements, the number of valence electrons can indicate the group number.
The s2 indicates the strontium’s valence electrons fill the s sublevel. Thus, strontium is in group 2 of the s-block.
The number of the highest energy level indicates the period number.
The 5 is 5s2 indicates that strontium is in period 5.
Use with Example Problem 1.
Problem
Strontium, which is used to produce red fireworks, has an electron configuration of [Kr]5s2. Without using the periodic table, determine the group, period, and block of strontium.
Response
ANALYZE THE PROBLEM
You are given the electron configuration of strontium.
EVALUATE THE ANSWER
The relationships between electron configuration and position on the periodic table have been correctly applied.
KNOWN
UNKNOWN
Electron configuration = [Kr]5s2
Group = ?
Period = ?
Block = ?
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Classification of the Elements

13. Review Essential Questions
Why do elements in the same group have similar properties?
Based on their electron configurations, what are the four blocks of the periodic table?
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Classification of the Elements