1. Periodic Trends

2. What is a trend? A trend is the general direction in which something tends to move.

3. The Periodic Table of Elements 1869 – Dmitri Mendeleev published a table organizing the elements in order of increasing atomic mass. He put questions marks in places for elements he predicted would be discovered. They were found. This made people see the usefulness of the Periodic Table. We now organize elements by atomic number because we know more about the structure of the atom. (mostly the same as when organized by mass) Periodic Law (Periodicity) – when elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.

4. Mendeleev’s Periodic Table Dmitri Mendeleev

5. The Periodic Law Mendeleev even went out on a limb and predicted the properties of 2 (at the time) undiscovered elements. He was very accurate in his predictions, which led the world to accept his ideas about periodicity and a logical periodic table. Properties repeat at regular intervals when elements are arranged according to increasing atomic number Group/family = column; Period = row

6. Metals, Nonmetals, Metalloids How can you identify a metal? What are its properties? What about the less common nonmetals? What are their properties? And what the heck is a metalloid?

7. Metals, Nonmetals, Metalloids There is a zig-zag or staircase line that divides the table. Metals are on the left of the line, in blue. Nonmetals are on the right of the line, in orange.

8. Metals, Nonmetals, & Metalloids (Semimetals) Metallic Properties Form + ions Shiny / lustrous Malleable (hammered into thin sheets) Ductile (drawn into a wire) Good Conductors of heat and electricity They are mostly solids at room temp. What is one exception?

9. Examples of Metals Potassium, K reacts with water and must be stored in kerosene Zinc, Zn, is more stable than potassium Copper, Cu, is a relatively soft metal, and a very good electrical conductor. Mercury, Hg, is the only metal that exists as a liquid at room temperature

10. Nonmetals Properties of Nonmetals Form - ions Dull Brittle Insulators = poor conductors of heat and electricity Many are gases or solids at room temperature

11. Examples of Nonmetals Sulfur, S, was once known as “brimstone” Microspheres of phosphorus, P, a reactive nonmetal Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

12. Metalloids/Semimetals Metalloids (semimetals) Have the properties of both metals and semimetals They are shiny but brittle. And they are semiconductors. What is our most important semiconductor?  Boron, B  Germanium, Ge  Arsenic, As  Antimony, Sb  Tellurium, Te

13. Metal/Metalloid/Nonmetal Metals Metalloids Nonmetals

14. Solid, Liquid, & Gas at room temperature

15. Diatomic Gases (memorize) Gaseous elements that occur as diatomic molecules whenever uncombined N 2, O 2, F 2, Cl 2, Br 2, I 2, H 2

16. Classification of Elements Periods - horizontal rows Groups – (families) columns Atoms with similar properties. They are similar because they all have the same number of valence (outer shell) electrons, which governs their chemical behavior. Blocks = regions Elements in the same group have similar chemical properties

17. The Periodic Table Period Group or family Period Group or Family

18. Groups: Alkali Metals Alkali Metals (Group IA, first column) Soft, extremely reactive metals React with cold water to form hydrogen gas (violent reaction) Form +1 ions React with halogens (17) to form salts

19. Alkaline Earth Metals Alkaline Earth Metals (Group IIA, second column) Soft, reactive metals Compounds are a major components of earth’s crust Forms +2 ions

20. IIIA – Boron Family +3 Ions Metallic characteristic increases down the group IVA - Carbon Family + or – 4 Ions VA – Nitrogen Family -3 Ions VIA – Oxygen Family -2 Ions O is the most abundant element on Earth

21. Halogens (Group VIIA, 17) Poisonous and extremely reactive nonmetals F and Cl are yellow-green gases Br is a volative red-brown liquid I is a volative blue-black solid All form –1 ions

22. Noble/Inert Gases Noble/Inert Gases (Group 0, last column – 18 or 8A) All are monatomic gases A.k.a inert gases; almost completely unreactive

23. Important Blocks: Transition Metals (B’s) Elements in the region form the 3rd to 12th columns Hard, dense metals Less reactive than Group 1A and 2A Rare Earth Metals/Inner Transition Metals Elements in the annex at the bottom of the table Main Group/Representative Elements All elements except the transition and rare earth metals All numbers end with A (1, 2, 13-18)

24. Representative Elements (1,2,13 – 18) 6A 1A 7A 5A 4A 3A 2A 8A 1 B  10 B

26. Transition Metals Alkaline Earth Metals Noble Gases Inner Transition/Rare Earth Metals Halogens Alkali Metals

27. Atomic Number = # of protons Atomic Mass = # of protons & neutrons INC

28. Nuclear pull = electrostatic attraction of + nucleus for the negative outer e- Shielding = e- in between nucleus & outer e- shield pull INC Constant

29. Atomic Radius = the distance between the nucleus and the outermost electrons. e- are added to successively higher energy levels. We remain in the same principle energy level. Each element has one p+ and one e- more than the preceding element. The nuclear pull increases pulling each new e- closer to the nucleus. INC

30. H 0.030 Na 0.157 K 0.203 In 0.150 Sr 0.191 Rb 0.216 Sn 0.140 Sb 0.140 Te 0.137 I 0.133 Ca 0.174 Ga 0.125 Ge 0.122 As 0.121 Se 0.117 Br 0.114 Mg 0.136 Al 0.125 Si 0.117 P 0.110 S 0.104 Cl 0.099 Li 0.123 Be 0.089 B 0.080 C 0.077 N 0.070 O 0.066 F 0.064 The atomic radii of these representative elements are given in nanometers (nm). Increasing atomic radii

31. Period Trend: Atomic Radius

32. Ionic Radius (Size) Size or radius of an ion INC CationsAnions The overall trend is the same as Atomic size – for the same reasons, however: Cations have lost e- so they are smaller Anions have gained e- so they are larger

33. O 2- 0.140 F - 0.136 Be 2+ 0.031 Li + 0.060 Cs + 0.169 Tl 3+ 0.095 K + 0.133 Ca 2+ 0.099 Na + 0.095 N 3- 0.171 Cl - 0.181 S 2- 0.184 P 3- 0.212 As 3- 0.222 Ba 2+ 0.135 Rb + 0.148 Sr 2+ 0.113 In 3+ 0.081 Sn 4+ 0.071 I - 0.216 Te 2- 0.221 Sb 3- 0.245 Ga 3+ 0.062 Ge 4+ 0.053 Se 2- 0.198 Br - 0.195 Pb 4+ 0.084 Al 3+ 0.050 Mg 2+ 0.065 Si 4+ 0.041 B 3+ 0.020 C 4+ 0.015 The ionic radii shown here are given in nanometers.