Periodic Trends

1. Periodic Trends Elemental Properties and Patterns

2. Periodic Table • Periodicity: regular variations (or patterns) of properties with increasing atomic number. Both chemical and physical properties vary in a periodic (repeating) pattern. • Group: vertical column of elements (“family”) • Period: horizontal row of elements

3. Periodic Table and Periodicity Chemistry: The Periodic Table and Periodicity 1. Who first published the classification of the elements that is the basis of our periodic table today? 2. By what property did Mendeleev arrange the elements? 3. By what property did Moseley suggest that the periodic table be arranged? 4. What is the periodic law? 5. What is a period? How many are there in the periodic table? 6. What is a group (also called a family)? How many are there in the periodic table? DMITRI MENDELEEV ATOMIC MASS ATOMIC NUMBER THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY A HORIZONTAL ROW IN THE PERIODIC TABLE; 7 A VERTICAL COLUMN IN THE PERIODIC TABLE; 18

4. The Periodic Law • Mendeleev understood the ‘Periodic Law’ which states: • When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

5. Metals, Nonmetals, & Metalloids 1 Nonmetals 2 3 4 Metals 5 6 7 Metalloids Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349

6. Groups of Elements Elements with similar chemical behavior are in the same group. noble gases Transition metals alkali metals halogens alkaline earth metals lanthanides actinides

7. Metals • Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity. • They are mostly solids at room temp. • What is one exception? Mercury (Hg)

8. Nonmetals • Nonmetals are the opposite. • They are dull, brittle, nonconductors (insulators). • Some are solid, but many are gases, and Bromine is a liquid.

9. Metalloids • Metalloids, aka semi-metals are just that. • They have characteristics of both metals and nonmetals. • They are shiny but brittle. • And they are semiconductors. • What is our most important semiconductor?

10. Periodic trends Identifying the patterns

11. Metallic Characteristics metallic character increases metallic character increases metallic character increases

12. Periodic Table and Periodicity Chemistry: The Periodic Table and Periodicity 1. Who first published the classification of the elements that is the basis of our periodic table today? 2. By what property did Mendeleev arrange the elements? 3. By what property did Moseley suggest that the periodic table be arranged? 4. What is the periodic law? 5. What is a period? How many are there in the periodic table? 6. What is a group (also called a family)? How many are there in the periodic table? DMITRI MENDELEEV ATOMIC MASS ATOMIC NUMBER THE PROPERTIES OF THE ELEMENTS REPEAT PERIODICALLY A HORIZONTAL ROW IN THE PERIODIC TABLE; 7 A VERTICAL COLUMN IN THE PERIODIC TABLE; 18

14. Experiment Variable – factor in the experiment that is being tested

15. The factor that is changed is known as the independent variable (IV). • Also referred as “The Cause” • The factor that is measured or observed is called the dependent variable (DV). • Also referred as “The Effect”

16. Rule for Addition and SubtractionCalculating with Numbers Written in Scientific Notation In order to add or subtract numbers written in scientific notation, you must express them with thesame power of 10. Sample Problem: Add 5.8 x 103 and 2.16 x 104 2.74 x 104 (5.8 x103) + (21.6 x103) = 27.4 x 103 Exercise: Add 8.32 x 10-7 and 1.2 x 10-5 1.28 x 10-5

17. http://phet.colorado.edu/en/simulation/balloons

19. Attraction and Repulsion of Electrical Charges + + - - + - Particles with opposite charges attract one another. Particles with like charges repel one another.

20. Coulombic Attraction Depends on: 2. Distance between charges 2+ 2- 2+ 2- • 1. Amount of charge 2- 2+ 1+ 1-

21. Periodic Trends • atomic radius. • Radius is the distance from the center of the nucleus to the “edge” of the electron cloud.

22. Atomic Radii

23. Atomic Radii • Trend: decreases across a period WHY??? • As the # of protons in the nucleus increases, the positive charge increases and as a result, the “pull” on the electrons increases. • Trend: increases down a group WHY??? • The atomic radius gets bigger because electrons are added to energy levels farther away from the nucleus decreasing the “pull” or force of attraction.

24. Atomic Size Trends

25. Ionization Energy • Definition: energy required to remove outer electrons from an atom

26. Hungry for Tater Tots? Mr. C at 7 years old.

27. OUCH!!

28. Ionization Energy • Trend: increases across a period • WHY??? • All the atoms in the same period • Increasing the number of protons increase the “pull” or force of attraction. • Trend: decreases down a group • WHY??? • Electrons are further away from the positive “pull” of the nucleus and therefore easier to remove.

29. He Ne Ar Kr H Li Na K Rb First Ionization energy Atomic number

30. Electronegativity • Definition: the tendency of an atom to attract electrons to itself when chemically combined with another element

31. Electronegativity • Trend: increases across a period (noble gases excluded!) • WHY??? • Nuclear charge is increasing, atomic radius is decreasing; attractive force that the nucleus can exert on another electron increases. • Trend:decreases down a group • WHY??? • The electrons are farther away from the nucleus; decreased attraction, so decreased electronegativity

32. ElectronegativityTrends

33. Summing Up Periodic Trends

34. Summing Up Periodic Trends Increasing ionization energy Increasing Ion radius

35. Which has the largest atomic radius? 7. Br- Br 8. Al+ Al As an atom gains electrons, the atom gets bigger As an atom loses electrons, the atom gets smaller