1. PART 1 DEFINITION AND IMPORTANCE OF PERIODIC TRENDS

2. Periodic trends are trends on the periodic table in properties of elements that you observe when going: 1) left to right across a period (a __________________ trend) or 2) going down a group (a __________________ trend)

3. Why does an atom’s size or ability to lose or gain electrons matter? Trends among elements in the periodic table often involve: 1) their size or 2) their ability to lose or attract electrons

4. Almost all of chemistry is a result of atoms

5. As a result, much of what goes on in our world is at least partly a result of electrons “moving around!”

6. Here is an example of a question we can answer by using periodic trends: WHY ARE ALKALI METALS SO REACTIVE?? When you can answer this question, we’ll view their reactivity by throwing some sodium metal in water!

7. PART 2 PERIODIC TREND: ATOMIC RADIUS

8. The size of an atom is determined by its ATOMIC RADIUS Can you measure atomic radius by simply measuring the distance between the nucleus and the edge of the atom?

9. What is the accepted way for physically measuring atomic radius?

11. ATOMIC RADIUS

12. As you go down a family, the atomic radius INCREASES DECREASES. Why? As you go from left to right in a period, atomic radii INCREASE DECREASE Why? Review Notes on the “Why” of Periodic Trends

13. The more __________ the nucleus pulls on its valence electrons, the __________ the atoms get.

14. PART 3 IONS

15. All of the other trends we will discuss have to do with how easily an atom _______, ________,or________ electrons So – what is formed when an atom gains or loses electrons?

16. Section 6-3 An ___________ is an atom or bonded group of atoms with a positive or negative charge. A positive ion has ________ electrons A negative ion has ________ electrons

17. Section 6-3 NEGATIVE IONS(cont.) When atoms ______________ electrons, they can become larger, because the addition of an electron increases electrostatic repulsion.

18. When atoms _____________ electrons and form positively charged ions, they always become ______________ for two reasons: 1.The loss of a valence electron n can leave an empty outer orbital resulting in a small radius. 2.Electrostatic repulsion decreases allowing the electrons to be pulled closer to the radius. POSITIVE IONS