Classification of the Elements

1. Classification of the Elements Objectives: AHSGE Reading 4.3 Discern organizational patterns. Other AOD C.3.2 Recognize periodic trends of elements, including the number of valence electrons, atomic size, and reactivity.

2. Organizing the Elements by Electron Configuration • We know valence electron configurations of the group A elements. Now let’s look at valence electrons and periods. • Write the noble gas configurations of the group 1A elements straight down in a column. • What is the 1st trend you notice? • What other trend do you see?

3. Organizing the Elements by Electron Configuration (continued) • The energy level of the valence electrons is the same as the period number the element is found in! • So in what energy level would the valence electrons for gallium (Ga) be found? • What about titanium (Ti)?

4. s-, p-, d-, and f- Block Elements • s-block elements have valence electrons in the s orbital. • What groups would this be? • p-block elements are found in groups 3A-8A. • This block’s elements have filled or partially filled p orbitals. • How many groups on the periodic table are in the p-block? Why is this so?

5. s-, p-, d-, and f- Block Elements (continued) • The first period contains NO p-block elements. The first p-block element is boron. • What period is boron in? • Why are there no p-block elements in the first period? Answer: The 1st period elements only have a 1s orbital.

6. s-, p-, d-, and f- Block Elements (continued) • d-block elements are the transition metals. • USUALLY contain a filled outermost s-orbital of energy level n, and a filled or partially filled d-orbital of energy level n-1. • Example: Scandium (Sc) is in period ___. • Sc has a filled 4s orbital and a partially filled 3d orbital.

7. s-, p-, d-, and f- Block Elements (continued) • So what s-orbital and what p-orbital would be filled or partially filled for tungsten (W)? Answer: 6s and 5p. • How many d orbitals are there? Answer: 5 • How many electrons can those d orbitals hold? Answer: 10

8. s-, p-, d-, and f- Block Elements (continued) • How many “groups” (columns) does the d-block span on the periodic table? • f-block elements are the inner transition metals. • Characterized by a filled or partially filled outermost s-orbital, and filled or partially filled 4f or 5f orbital. • f-orbitals do not fill in a predictable manner.

9. Overview/Review • Moving DOWN through the periods, the principal energy level increases. • As principal energy level increases, so does the number of energy sublevels containing electrons. • Period 1 has only s-block elements. • Periods 2 and 3 have s- and p-orbitals. • Periods 4 and 5 have s-, p- and d-orbitals. • Periods 6 and 7 have ??????

10. Assignments  • Practice Problems, p.162 (7-9) • In which block of the periodic table would each of the elements identified in #9 be found? • Complete Study Guide for Content Mastery, pp.33-34 (16-26).