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# 8.3: Multimedia Resources for Chapter 8

Difficulty Level: At Grade Created by: CK-12

Copy and distribute the lesson worksheets. Ask students to complete the worksheets alone or in pairs as a review of lesson content.

## The Periodic Table and Electron Configuration Worksheet

When Mendeleev organized the periodic table, he placed the elements in vertical columns according to their chemical behavior. That is, elements were placed in the same vertical columns because they behaved similarly in chemical reactions. All the alkali metals $(Li, Na, K, Rb, Cs)$ react with water to produce heat, hydrogen gas, and the metal hydroxide in solution. Essentially, the only difference in the reactions is that the larger alkali metals react faster than the smaller ones. The vertical columns of elements are frequently referred to chemical “families” because of their similar chemical characteristics.

When quantum theory generated electron configurations which demonstrated that the elements in the same family have the same outer energy level electron configuration, the reason these elements behaved similarly became clear. Since chemical behavior is determined by outer energy level electron configuration, it was clear that elements that behaved similarly should have similar electron configuration.

The Electron Configuration of Family 1A Elements
Element Electron Configuration
Li $1s^22s^1$
Na $1s^22s^2sp^63s^1$
K $1s^22s^2sp^63s^23p^64s^1$
Rb $1s^22s^2sp^63s^23p^64s^23d^{10}4p^65s^1$
Cs $1s^22s^2sp^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^66s^1$
The Electron Configuration of Family 7A Elements
Element Electron Configuration
F $1s^22s^22p^5$
Cl $1s^22s^2sp^63s^23p^5$
Br $1s^22s^2sp^63s^23p^64s^23d^{10}4p^5$
I $1s^22s^2sp^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^5$

Exercises

1. If the outermost energy level electron configuration of an atom is $ns^2np^1$,
1. to which family does it belong?____________
2. is the atom a metal, metalloid, non-metal, or a noble gas? ____________
3. how many valence electrons does it have? ____________
2. If the outermost energy level electron configuration of an atom is $ns^2np^4$,
1. to which family does it belong? ____________
2. is the atom a metal, metalloid, non-metal, or a noble gas? ____________
3. how many valence electrons does it have? ____________
3. If the outermost energy level electron configuration of an atom is $ns^2np^6$,
1. to which family does it belong? ____________
2. is the atom a metal, metalloid, non-metal, or a noble gas? ____________
3. how many valence electrons does it have? ____________
4. The electron configuration of an element is $[Ar]4s^23d^3$.
1. What is the identity of the element? ____________
2. In what period does the element belong? ____________
3. In what group does the element belong? ____________
4. Is the element a main group element, a transition element, a lanthanide, or an actinide? ____________
5. Write the electron configuration of only the outermost energy level for an element that is in family 5A of the fifth period of the periodic table. ____________
6. Write the electron configuration of only the outermost energy level for an element that is in family 8A of the third period of the periodic table. ____________

• The worksheet answer keys are available upon request. Please send an email to teachers-requests@ck12.org to request the worksheet answer keys.

Aug 18, 2012

Aug 13, 2014