1. The Periodic Table Unit 5

2. Ion Cation – when an atom loses an electron, positive atom after losing an electron. Metals become cations. Anion – when an atom gains an electron, negative atom after gaining an electron. Nonmetals become anions.

3. Mendeleev First scientist to organize a periodic table of elements.

4. Mendeleev’s ptable

5. Why is the Periodic Table important to me? The periodic table is the most useful tool to a chemist. You get to use it on every test. It organizes lots of information about all the known elements.

6. Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Imagine going to a grocery store with no organization!! Difficult to find information. Chemistry didn ’ t make sense.

7. Dmitri Mendeleev: Father of the Table HOW HIS WORKED… Put elements in rows by increasing atomic weight. Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He broke the pattern of increasing atomic weight to keep similar reacting elements together.

8. The Current Periodic Table Mendeleev wasn ’ t too far off. Now the elements are put in rows by increasing ATOMIC NUMBER!! The horizontal rows are called periods and are labeled from 1 to 7. The vertical columns are called groups are labeled from 1 to 18.

9. Groups…Here ’ s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons. They will form the same kinds of ions.

10. Families on the Periodic Table Columns are also grouped into families. Families may be one column, or several columns put together. Families have names rather than numbers. (Just like your family has a common last name.)

11. Hydrogen Hydrogen belongs to a family of its own. Hydrogen is a diatomic, reactive gas. Hydrogen was involved in the explosion of the Hindenberg. Hydrogen is promising as an alternative fuel source for automobiles

12. Alkali Metals 1 st column on the periodic table (Group 1) not including hydrogen. Very reactive metals, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife https://www.youtube.com/watch ?v=cqeVEFFzz7E https://www.youtube.com/watch ?v=cqeVEFFzz7E

13. Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

14. Transition Metals Elements in groups 3- 12 Less reactive harder metals Includes metals used in jewelry and construction. Metals used “ as metal. ”

15. Boron Family Elements in group 13 Aluminum metal was once rare and expensive, not a “ disposable metal. ”

16. Carbon Family Elements in group 14 Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Silicon and Germanium are important semiconductors.

17. Nitrogen Family Elements in group 15 Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world ’ s nitrogen is not available to living things. The red stuff on the tip of matches is phosphorus.

18. Oxygen Family or Chalcogens Elements in group 16 Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

19. Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature. Used as disinfectants and to strengthen teeth.

20. The Noble Gases

21. Elements in group 18 VERY unreactive, monatomic gases Used in lighted “ neon ” signs Used in blimps to fix the Hindenberg problem. Have a full valence shell. https://www.youtube.co m/watch?v=1y0zhWp_4S w https://www.youtube.co m/watch?v=1y0zhWp_4S w

22. Section A: Complete the chart using a periodic table to help you.

23. Answer these questions: An atom that gains one or more electrons will have a ____________________ charge. An atom that loses one or more electrons will have a ____________________ charge. An atom that gains or loses one or more electrons is called an ____________. A positive ion is called a ______________ and a negative ion is called an _______________. CATION ANION “An-Eye-On” “Cat-Eye-On”

24. What is an ionic bond? Atoms will transfer one or more ________________ to another to form the bond. Each atom is left with a ________________ outer shell. An ionic bond forms between a ___________ ion with a positive charge and a ________________ ion with a negative charge. Example B1: Sodium + ChlorineExample B2: Magnesium + Iodine ELECTRONS COMPLETE METAL NONMETAL

25. Atomic Radius Measured from nucleus to outermost electron. Unit commonly used is pm picometer= 10 -12 m Example: iodine atomic radius 140pm

26. How does atomic radius change across a period? It is smaller to the right. Why? More protons in the nucleus  higher electrical force pulls electrons closer to nucleus. – makes atom more tightly smaller.

27. How does atomic radius change down a group? It is larger down the group. Why? Valence electrons are at higher energy levels and are not bound as tightly to the nucleus because they are screened or shielded ( pushed away) by other electrons in inner levels.

28. The Periodic Table and Atomic Radius

29. Example: Which is larger: a lithium atom or a fluorine atom? A lithium atom

30. Example: Which is larger: an arsenic atom or a sulfur atom? An arsenic atom

31. Ionization energy Ionization energy is the amount of energy needed to remove an electron from an atom.

32. Ion Positive ion---removal of electron CATION Negative ion--- addition of electron ANION

33. How does ionization energy change down a group? The ionization energy decreases as you move down a group. Why? – The size of the atom increases. – Electron is further from the nucleus. – Easier to take electrons.

34. How does ionization energy change across a period? The ionization energy increases as you move from left to right across a period. Why? – Nuclear charge because the atomic number increases. – Attraction of the electron to the nucleus increases.

35. Ionic size Metallic elements easily lose electrons. Non-metals more readily gain electrons. How does losing or gaining an electron effect the size of the atom (ion) ?

36. Positive ions Positive ions are always smaller than the neutral atom. Loss of outer shell electrons.

37. Negative Ions Negative ions are always larger than the neutral atom. Gaining electrons.

38. Electronegativity: the ability of an atom in a bond to pull on the electron. (Linus Pauling)

39. Electronegativity When electrons are shared by two atoms a covalent bond is formed. When electrons are transferred from one atom to another an ionic bond is formed. When the atoms are the same they pull on the electrons equally. Example, H-H. When the atoms are different, the atoms pull on the electrons unevenly. Example, HCl

40. Trends in Electronegativity Electronegativity generally decreases as you move down a group. Electronegativity of the representative elements (Group A elements/not transition) increases as you move across a period.

41. Electronegativities of Some Elements Element Pauling scale F 4.0 highest possible # Cl 3.0 O 3.5 N 3.0 S 2.5 C 2.5 H 2.1 Na 0.9 Fr0.7 lowest

42. Note Most electronegative element is F (EN 4.0) Least electronegative stable element is Cs (EN 0.7)

43. Review Ionization EnergyElectronegativity Amount of energy needed to take an electron from an atom. Nonmetals do not like to give up electrons. HIGH The ability for an atom to gain an electron. Nonmetals like to take electrons. HIGH

44. https://www.youtube.com/watch?v=mlRhLicN o8Q https://www.youtube.com/watch?v=mlRhLicN o8Q Naming ions and acids