answer all questions (10 points)

7. Indicates which properties allow to classify in the same group: a) alkali metals, b) alkaline earth metals, c) halogens, d) noble gases.

8. The elements in group 8A of the periodic table are called noble gases. What is the meaning of "noble" in this context? Why are noble gases classified as chemical elements, if they -practically- lack the fundamental property of chemical elements, which is the ability to form chemical compounds?

9. Group the following elements in pairs so that their physical and chemical properties are similar: F, K, P, Na, Cl, and As.

10. Write the external electron configurations of: a) alkali metals b) alkaline earth metals c) halogens d) noble gases.

11. Group the following electronic configurations into pairs that can have atoms with similar chemical properties: 1s22s22p63s23p5 1s22s22p63s2 1s22s22p3 1s22s22p63s23p6 4s23d104p6 1s22s2

12. What does it mean to say that two ions, or an atom and an ion, are isoelectronic?