The Periodic Table

Bell Ringer – turn in Define the following: 1.Periods – 2.Groups/Families – Name 2 elements in the following classifications: 3.Alkali metals 4.Alkaline earth metals 5.Nonmetals 6.Halogens 7.Noble gases 8.Metalloids

Objectives Students will be able to – Explain why elements in the same group have similar properties – Identify four blocks of the periodic table based on electron configuration.

Valence electrons Recall: – Valence e- are e- in the highest principal energy level of an atom Atoms in the same group have similar chemical properties b/c they have the same # of valence e-.

Valence electrons Period – the energy level of an element’s valence electrons indicates the period on the periodic table in which it is found. – Ex: Lithium (Li) – its valence e- is in the second energy level and Li is found in period 2 Gallium (Ga) – its valence e- is in the fourth energy level and Ga is found in period 4

Valence electrons Group number – corresponds to valence e-’s for representative elements (s & p-blocks)

#1-15 on your 6.2 worksheet 1. h 2. f 3. n 4. a 5. k 6. d 7. l 8. o 9. I 10. g 11. b 12. m 13. c 14. j 15. e

16 Why do sodium and potassium, which belong to the same group in the periodic table, have similar chemical properties? They have the same number of valence e-

17 How is the energy level of an element’s valence electrons related to its period on the periodic table? Give an example. The energy level indicates the period. Ex: Calcium’s valence electrons are in the fourth energy level and lithium is found in period 4.

18 How many blocks is the periodic table divided? four

19 What groups of elements does the s-block contain? Groups 1A (alkali metals) & 2A (alkaline earth metals) And Helium (He)

20 Why does the s-block portion of the periodic table span 2 groups? The s-orbital holds a maximum of 2 e-

21 What groups of elements does the p-block contain? Groups 3A through 8A (metals, metalloids, nonmetals)

22 Why are members of group 8A virtually unreactive? They have both their s orbitals and their p orbitals completely filled with electrons. They have 8 valence electrons making them very stable therefore they are very unreactive.

23 How many d-block elements are there? 40

24 What groups of elements does the d-block contain? Group B elements

25 Why does the f-block portion of the periodic table span 14 groups? The seven f orbitals hold a maximum of 14 electrons.

6.1 worksheets Lets go over those! Will do it with equity sticks

6.3 Periodic Trends Atomic Radius Ionic Radius – ion Ionization Energy – Octet rule Electronegativity

Atomic Radius Atomic radii generally decrease as you move left to right across a period, and increase as you move down a group. (size of atom)

ions Positive ions are smaller than the neutral atoms from which they form Negative ions are larger than the neutral atoms from which they form

Ionic Radius Ionic radii of both positive and negative ions decrease as you move left to right across a period. Ionic radii of both + and – ions increase as you move down a group

Ionization energy How strong an atom holds on to its e- Generally increase L-R Decrease down the periodic table

Octet rule Atoms tend to lose, gain or share e- to get 8 valence e-

Electronegativity An atom’s ability to attract e- in a chemical bond Generally increases L-R Decreases down a group

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