Physical Science

1. Physical Science Chapter 4Elements & The Periodic Table

2. Today’s lesson…… • Objective of today’s lesson • Describe the mass of an atom and its parts in terms of amu • Explainwhat the atomic number of an element is • Calculate atomic mass number or number of neutrons The Modern Atomic Model……

3. Read pages 106 to 108 and complete the following idea tree/concept map in your notes……………

4. The modern atomic model has three fundamental particles The Electron The Proton The Neutron Has a negative charge Relative mass is 1/1836 Found in clouds outside the nucleus Has a positive charge Is in the nucleus Has a relative mass of 1 (~1836X more than an electron) Has about the same mass as a proton (1 amu) Has no charge Is in the nucleus

5. Parts of an Atom • An atom consists of a nucleus surrounded by one or more electrons • Atoms are electrically neutralw/ the same number of protons as electrons. • Majority of the atom is empty space. If nucleus were the size of a pencil eraser, the closest electron would be 100 yards away! • Subatomic Particles • Protons • Neutrons • Electrons • Nucleus: Tightly packed Protons & Neutrons • Electrons Orbiting nucleus @ ~ speed of light!!

6. Atomic Mass • How much does an atom “weigh”? • What is the mass of an atom? • SI Unit for mass is the Gram…. Way toooo big to accurately “mass” an atom • Came up w/ new unit, an AMU (atomic mass unit) • 1 AMU = mass of 1 Proton • mass of subatomic particles • Proton = 1 AMU • Neutron = 1 AMU • Electron = .0005 AMU • Atomic Mass = the total # of both Protons& Neutrons in the atom • ( we don’t worry about the mass of the electrons since they have almost no mass)

7. Atomic Number • By definition: • The Atomic Number = the number of Protons present in the nucleus of an atom • Each Element in the Periodic Table has a different number of Protons, therefore each element has a different, unique, atomic number. “Smaller” number is always the atomic #, therefore the number of protons present “Large” number is always the Atomic Mass which tells us the total # of both Protons & Neutrons present When reading the Periodic table notice each element has a unique 1 or 2 letter symbol and “big” & “small” number listed

8. Electrical Atomic Charge • Electrical charge – all atoms have a neutral charge • ( a zero net electrical charge) • Protons have a positive (+) electrical charge • Neutrons have a neutral (0) electrical charge • Electrons have a negative (-) electrical charge • Since the net electrical charge is 0 (neutral), if you have 10 Protons (10 “+” charges) then there must be 10 “-” charges (10 electrons) present to balance out the atom. • Therefore, as long as you know the Atomic #, you know the # of Protons and also the # of Electrons!! For example: Carbon has an atomic # of 6, it therefore has 6 Protons which has an electrical charge of +6, to make the atom neutral we need 6 negative charges found in the 6 electrons orbiting the nucleus.

9. How many Neutrons are there? • Remember: • The Atomic # = the # of Protons • The Atomic mass = The # of both Protons & Neutrons. • Therefore, if you subtract the Atomic # (the number of Protons) from the Atomic mass (the number of both Protons & Neutrons) what is left over must be the number of Neutrons!! For Example w/ Carbon: Atomic Mass-Atomic # = # Neutrons Atomic Mass = 12, Atomic # 6 12 – 6 = 6 neutrons present in the Carbon nucleus

10. What makes an Element? What are isotopes?

11. What makes an Element? • Over 117 different elements • http://www.privatehand.com/flash/elements.html

12. OBJECTIVES: • Explain how the atomic number identifies an element.

13. How Do Atoms of Different Elements Differ? • Starting Simply The hydrogen atom has one proton and one electron. • Now for Some Neutrons The helium atom has two protons, two neutrons, and two electrons.

14. Elements Review……………… • The number of protons determines the element and it’s atomic number • Atomic Number = the number of protons • Atomic Mass Units (amu) = # of protons + # of neutrons • A neutral atom has the same number of electrons as protons

15. Elements Review……………… • Atoms have larger atomic numbers and more mass as you add more protons and neutrons • Carbon (C): 6 protons + 6 neutrons = 12 amu • Gold (Au): 79 protons + 118 neutrons = 197 amu • An atom does not have to have equal numbers of protons and neutrons

16. Hydrogen Protons: 1 Neutrons: 0 Electrons: 1 H 1 1

17. Sodium Protons: 11 Neutrons: 12 Electrons: 11 Na 11 23

18. Rhenium Protons: 75 Neutrons: 111 Electrons: 75 75 Re 186

19. 55 133 EXAMPLE How many protons, neutrons and electrons are found in an atom of Cs Atomic number = protons and electrons There are 55 protons and 55 electrons Mass number = sum of protons and neutrons 133 – 55 = 78 There are 78 neutrons

20. Isotopes What are they?

21. Isotopes Review… They have the same number of protons They have the same atomic number Isotopes are atoms that have the same number of protons but different numbers of neutrons (they are still the same element) Why? Which means? Lets review this more closely……….

22. Isotopes….......

23. Isotopes…....... • Telling Isotopes Apart You can identify each isotope of an element by its mass number. The mass number is the sum of the protons and neutrons in an atom.

24. Isotopes Atoms with the same number of protons but different numbers of NEUTRONS Carbon -12 ? 6 Atomic # 6 6 N N N N Mass # 12 N N 12 N Carbon -14 6 Atomic # 6 8 N N N N N Mass # 14 N N N N 14

25. Name: ________________ Period : ______ Isotopes Atoms with the same number of protons but different numbers of NEUTRONS B-11 Atomic # N Mass # B-10 Atomic # N Mass #

26. IsotopesAtoms of the same element can have different numbers of neutrons The number of Neutrons in an atom will sometimes vary, that’s why the atomic mass of the elements is not an even number. For Hydrogen, the mass is 1.008. Most atoms of Hydrogen have 0 neutrons, but some have 1 neutron and a very very few will have 2 neutrons. When you “weigh” trillions of Hydrogen atoms you find that almost all of them will not have any Neutrons, & several of the atoms will have 1 neutron and maybe 1 or 2 will have 2 Neutrons. If you were to take an average of all of the Hydrogen atoms in your sample, the atomic mass would reflect the different Isotopes present and be 1.008 AMU’s.

27. Organizing the ElementsObjectives: What is the periodic table ? What information can be obtained from the table ? How the periodic table is organized How an elements properties can be predicted

28. The scientists who organized it….. • 1829 J.W. Dobereiner (German) organized elements into triads based on similar properties and atomic mass • 1869 Dmitri Mendeleev (Russia) published a classification schemes for all elements (in order of atomic mass) • Lothar Meyer (Germany) published a nearly identical classification also in 1869 • Later, Henri Moseley (England) 1887-1915, established that each element has a unique atomic number, which is how the current periodic table is organized

29. Organizing the Elements • The periodic table is laid out by increasing atomic number as you go across and down the table Atomic # increases  Atomic # increases 

30. Across the Periodic Table Periods: Are arranged horizontally across the periodic table (rows 1-7) All elements in a period (row) have the same number of electron shells. (not the same as quantum orbitals) 2nd Period 6th Period

31. Down the Periodic Table Groups or Families:Are arranged vertically down the periodic table (columns or groups, 1- 18 or I-VIII A,B) Elements in a group have the same number electrons in their outer most shells, the valence shell. Alkali Family: 1 e- in the valence shell Halogen Family: 7 e- in the valence shell

32. When using a table with groups 3A to 8A Listed, the group # equals the number of Valence electrons 8A (These are Groups 3A-8A) 1A 2A 3A 4A 5A 6A 7A (Groups 3B-12B)

33. C. Bohr Models Rings represent electron shells/energy levels Dots represent the electrons in each shell (e-). Pair them! Center circle is the nucleus with the number of protons and neutrons Example: Two elements in period 3 (three electron shells) Sodium 1e- 7e- 8e- 8e- 2e- 2e- • Chlorine P11 N12 P17 N18 *Add the electrons to each shell according to the number of elements in a row up to the element you are modeling

34. C. Dot Diagrams Dots represent the valence e-. EX: Sodium • EX: Chlorine

35. C. Electron Shells & Energy Levels When electrons in an atom are excited by electricity, light or heat they can jump up to another energy level When they come down they emit a specific wave length of light unique to that element! This is called an atomic emissions spectra 7e- 8e- 2e- P17 N18 Online Animations: http://einstein.byu.edu/~masong/htmstuff/Absorb2.html http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/spectroscopy.htm

36. “Need-to-Know Families “Old Fashion Names” of certain Families Alkali Metals Alkaline Earth Metals Noble Gases Halogens Chalogens Transition Metals

37. The Alkali Metals – Group 1 • Very reactive metals that have only one valence electron in the outer orbit and will freely give it away to become stable. Very soft metal (you could cut it w/ a plastic knife!). They form ionic bonds w/ Halogens and Chalogens. Examples include Sodium and Potassium.

38. The Alkaline Earth Metals – Group 2 • not as reactive as Alkali Metals, but still very reactive. They have two valence electrons and generally give them up to nonmetals to form ionic bonds. Examples include Calcium and Magnesium

39. Transition Metals – Groups 3 thru 12 • These all vary dramatically in reactivity, Their oxidation states (# of valence electrons) vary. They are a bridge between the very reactive Alkali and Alkaline Earth Metals and the nonmetals.

40. Chalogens AKA: Oxygen Family – Group 16 • nonmetals w/ 6 valence electrons, need 2 electrons to fill the outer shell. Most common oxidation state is -2. Examples are Oxygen (ozone is one of its allotropes), Sulfur (responsible for that rotten egg smell when it combines w/ oxygen to form sulfur dioxide) and Selenium (one of the few non metals that are also a good conductor of electricity).

41. Halogens – Group 17 • Very reactive nonmetals w/ 7 valence electrons. Need only one more electron to fill their outer shell. Will steal an electron from a reactive metal to form ionic bonds. Examples include Chlorine (the most abundant halogen), Iodine and Bromine (found in Seawater).

42. Noble Gases - Group 18 • Non reactive, have a full compliment of valence electrons, 8 and are called the “Inert Gases” because they do not react w/ other elements. Examples include Helium (very low mass and is used in filling children’s balloons and even airships and the “Goodyear Blimp) and Neon used in lighted bulbs to make a red glowing light ( a neon light).

43. More Need-to-Knows Transition Metals Actinides Lanthanides Rare Earth Elements – AKA Inner Transition Metals

45. Properties of Metals Metals are good conductors of heat and electricity. Metals are shiny. Metals are ductile (can be stretched into thin wires). Metals are malleable (can be pounded into thin sheets). A chemical property of metal is its reaction with water which results in corrosion.

46. The Metals • Examples include: Iron, Tin, Sodium, Calcium, Gallium • Most of the elements are metals. • Metals tend to form positive (+) ions. (They lose electrons) • Physical Properties • Such as hardness, shiny, malleability (pounded into shapes), • ductility (stretched or pulled into a wire) electrical conductivity and magnetic. • Chemical Properties • Form metallic bonds with metals and form Ionic bonds w/ nonmetals.

47. Properties of Non-Metals Non-metals are poor conductors of heat and electricity. Non-metals are not ductile or malleable. Solid non-metals are brittle and break easily. They are dull. Many non-metals are gases. Sulfur

48. Nonmetals are the light blue elements 17 Nonmetals • a. There are 17 nonmetals, each are located to the right of the zigzag line in the periodic table. • b. Non metals tend to steal electrons when they form negative (-) ions. • c. Physical Properties – in general the physical properties of nonmetals are opposite those of metals. non conductive, dull, not ductile or malleable, brittle, gaseous • d. Chemical properties – usually form ionic bonds when combined w/ metals (NaCl, FeO2, and CaCl2 ) and usually form covalent bonds when combined w/ other nonmetals (CO2, O2, C6H12O6) • e. Even though Hydrogen (H) is located in Group 1, it is still a nonmetal and exhibits oxidation states of +1 and -1.

49. Properties of Metalloids Metalloids (metal-like) have properties of both metals and non-metals. They are solids that can be shiny or dull. They conduct heat and electricity better than non-metals but not as well as metals. They are ductile and malleable. Silicon

50. Metalloids • AKA “semi metals” • 7 elements on the zigzag border between metals and the non metals. • Their properties will sometimes make them act like a metal and then sometimes act like a nonmetal. • Most important characteristic is their varying ability to conduct electricity. Silicon is used to make Semiconductors which are used in making computer chips.