The Periodic Table and Bonding

Periodic Table Review Periodic Table is divided into rows and columns known as groups or families and periods. The Group # is equivalent to the # of Valence Electrons. All periodic tables look differently depending on the specific features the publisher wants to highlight.

GROUPS Notice the group #s at the top of this table. The transition elements are different and will not be used as often as the far left and far right side of the table. These are labeled with letter B. We want to focus on the A groups. Look at group 3A. This group has 3 valence electrons. Look at group 8A. How many valence electrons does it have?

Groups Group 8A has 8 valence electrons. Remember that the number of valence electrons tells you a great deal about the reactivity of the element. You already learned that metals react by losing electrons. Also, reactivity decreases as you move from left to right across the table.

What’s the connection? Our metals start at group 1A on the far left. As you move across the table, the number of valence electrons increases. On the far right, our non-metals tend to react by gaining an electron. These elements are in a higher group number. So the elements with a low valence # want to lose an electron and the elements with a high valence # attempt to gain electrons.

Elements with a low valence # want to lose an electron and the elements with a high valence # attempt to gain electrons.

So….What’s the Magic Number? 8 8 Valence electrons makes an atom very happy and stable. When an atom has 8 valence electrons, it is COMPLETE! Look at your Noble Gases. What group are they in? How many valence electrons do they have? What does this tell you about their reactivity?

The noble gases What group are they in? 8A How many valence electrons do they have? 8 What does this tell you about their reactivity? They are unreactive. They are already Stable, Happy, and Complete! They don’t need to bond with other atoms!! They are not looking to gain or lose any electrons.

practice Draw the atom Sodium. Chemical Symbol Na. It is located in Group 1, Period 3 Na has 2e in the 1st level, 8e in the 2nd level, and 1e in the outer shell. Total of 11 electrons. The atomic # for Sodium is 11. This atom is neutral.

Practice continued Sodium would like to lose an electron. If it lost just one, it’s outer shell would be full, happy, and complete. It would make sodium more STABLE. Who might sodium want to bond with? An element in group 7! A group 7 element is looking to gain 1e and sodium is looking to lose 1e. This makes them a great bonding match. Chlorine is in group 7. Let’s draw chlorine!

Practice continued Chlorine has atomic number 17. It is in Group 7, Period 3. Cl has 2e in the 1st level, 8e in the 2nd level, and 7e in the outer shell. Total of 17 electrons. The atomic # for Chlorine is 17. This atom is neutral.

Na + Cl = NaCl or Table Salt This is a strong bonding match.

Independent practice Complete the “Atomic Dating Game” in Schoology Complete the “Element Couples Activity” in Schoology.