1. CHEMISTRY World of Zumdahl Zumdahl DeCoste

2. Chapter 3 Chemical Foundations: Elements, Atoms, and Ions

3. Top Ten 3

4.  An ELEMENT is the simplest form of a substance that can not be broken down.  A COMPOUNDis two or more elements bound together.  Presently there are 115 elements, 88 of which occur naturally.

5. Table 3.1 5

6. The 9 elements that account for 98% of the earths total mass (table 3.1)  Oxygen  Silicon  Aluminum  Iron  calcium  sodium  potassium  magnesium  hydrogen

7.  Names of the elements originated mainly from GREEK. LATIN, and GERMAN.  We abbreviate the elements to simplify.  Always us a CAPITAL letter for the first letter in element.  Use lower case if there is a second letter. –Ex: Hydrogen = H –Gold = Au (Aurum is latin for shiny)

8. Table 3.3 8

9. 1.Elements are made of tiny particles called atoms 2. All atoms of a given element are identical 3.Atoms of a given element are different from those of any other element. 4.Atoms of one can combine with atoms of another to form compounds 5.Atoms are indivisible in chemical processes, they are not created or destroyed. Dalton's Atomic Theory

10. Rules for Writing Formulas 1.Each atom present is represented by its element symbol. 2.The number of each type of atom is indicated by a subscript written to the right of the element symbol. 3.When only one atom of a given type is present, the subscript 1 is not written. Copyright© by Houghton Mifflin Company. All rights reserved. 10

11. Atomic Discoveries  J.J Thomson concluded that all atoms contain negative particles called electrons and must then also contain positive particles called protons.  William Thompson was for the PLUM- PUDDING model. He said the atom was like plum pudding ( bowl of pudding with things floating in it). Atom has pudding of positive and negative charges scattered around to counter balance.  Rutherford found that atoms must have a nucleus with a dense postive charge. He concluded that the nucleus contains protons, which are positive charge, and also neutrons which have no charge.

12. Figure 3.3: Plum Pudding model of an atom. 12

13. Figure 3.5: Rutherford’s experiment. 13

14. Figure 3.6: Results of foil experiment if Plum Pudding model had been correct. 14

15. Figure 3.6: Actual Results. 15

17. Atoms can be divided into 3 subatomic Particles: 1. Protons2. Neutrons3. Electrons orbitals 1/1800 -eElectron Nucleus10nNeutron nucleus1+pProton locationMassChargeSymbolParticle

18. Figure 3.9: A nuclear atom viewed in cross section. 18

19. Figure 3.10: Two isotopes of sodium. 19

20. ATOMIC NUMBER means the number of protons in an element MASS NUMBER means the number of Neutrons and Protons in the element Na 23 11 23 = mass number = protons + neutrons 11 = atomic number

21. Isotopes  Isotopes are atoms of the same element that have different numbers of neutrons.  Isotopes have the same atomic number, but different mass number

22. Ion: an element, or atom with a charge  Charged because of movement or transfer of electrons  Cation: positive ion, electrons are lost (example: Mg 2+ )  Anion: negative ion, electrons are gained (example: Cl - )  Charges are represented with superscript  Ionic compounds contain metal & non- metal – net charge equals zero

23. Figure 3.19: The ions formed by selected members of groups 1, 2, 3, 6, and 7. 23

24. Figure 3.20: Pure water does not conduct a current. 24

25. Figure 3.20: Water containing dissolved salt conducts a current. 25

26. The Periodic Table  The known elements were organized according to their atomic masses in 1871 by MENDELEEV.  The modern version of his table is called THE PERIODIC TABLE OF the ELEMENTS  The Horizontal rows are called PERIODS  The vertical columns are called GROUPS  The Main Group Elements are in groups 1,2,13,14,15,16,17,and 18  Transition Metals are elements in groups 3-12

27. The periodic table. 27

28. All Elements can be divided into three main categories:  Metals  Nonmetals  Metalloids

29. Elements classified as metals and nonmetals. Elements classified as metals and nonmetals. 29

30. Most of the elements are METALS and are located on the LEFT side of the Periodic Table and include the Lanthanides and Actinides. Properties of Metals: 1. Good conductors of HEAT and ELECTRICITY 2. Have Metallic Luster (shiny and reflect light well) 3. Are Malleable (can be hammered into thin sheets) 4. are Ductile (can be drawn into wires) All metals, except Hg (mercury) are solid at room temperature, 25 ° C.

31. The upper right hand corner of the Table is where the NON- METALS are found, including Hydrogen Properties of NONMETALS: 1. poor conductors of HEAT and ELECTRICITY 2. Do Not have a shiny appearance or reflect light well 3. are brittle in the solid form

32. The Metalloids are the 6 elements: B, Si, Ge, As, Sb, and Te * sometimes called semi-metals - They separate the metals and non-metals and be found hugging the staircase line. - Properties: -1. poor conductors of heat -2. semi-conductors of electricity -3. have a dull appearance and do not reflect light as well -4. are brittle solids at 25° C.

33. Silicon computer chip The most important metalloid is silicon – it’s used to make computer chips

34. Group 1 Elements are also called ALKALI METALS Examples are: Li, Na, K, Rb, Cs, and Fr. Group 2 Elements are ALKALINE EARTH METALS Examples are: Be, Mg, Ca, Sr, Ba, and Ra

35. Group 17 Elements are called the HALOGENS Examples are F, Cl, Br, I, A Group 18 elements are called NOBLE GASES (or inert gases, or rare gases) Examples are : He, Ne, Ar, Kr, Xe, Rn

36. ALKALI METALS - are very Reactive, which means they readily combine with other elements. ** React with chlorine gas to form a metal chloride ** React with water to form hydrogen gas

37. ALKALINE EARTH METALS - they are reactive, but not as reactive as the alkali metals. ** react with chlorine gas to form a metal chloride ** react with water to form hydrogen gas (sodium reacts with water at room temperature, but magnesium won’t react with water unless the water is boiling.)

38. Alkali Metals and Alkaline Earth Metal have been used in everyday items such as: *Lithium was used to treat manic depression -7-UP used to contain lithium *Magnesium is used in disposable flash bulbs *Calcium can be found in limestone, chalk, marble, and coral.

39. The Halogens * are non-metals and exist as diatomic molecules ( a molecule that contains 2 atoms. - Homonuclear diatomic molecules are the same element F 2, Cl 2, Br 2, and I 2 -Heteronuclear diatomic molecules are different elements: CO, NO,

40. Halogens are reactive and react with Hydrogen gas to form compounds with the formula (HX) Ex. -HF is used to etch glass (lightbulbs, TV tubes) -HCl is used to digest food

41. Nitrogen gas contains NXN molecules. 41

42. Oxygen gas contains OXO molecules. Oxygen gas contains OXO molecules. 42

43. Noble Gases: - They are all colorless gases at 25°C. - They are unreactive (very stable) Ex: Neon, used in neon signs (zapped by electricity)

44. A collection of argon atoms. 44

45. Table 3.5 45

46. Figure 3.15: The decomposition of two water molecules. 46

47. Terms to Know: Melting Point: goes from solid to liquid Freezing point: goes from liquid to solid Evaporation: goes from liquid to gas Condensation: goes from gas to liquid Sublimation: goes from solid to gas Deposition: goes from gas to solid