Table of Contents

1. Book K Table of Contents • Introduction to Atoms • Organizing the Elements • Metals • Nonmetals and Metalloids • Radioactive Elements Ch. 3 – Sec. 1: Pg. 74-79 Ch. 3 – Sec. 2: Pg. 80-87 Ch. 3 – Sec. 3: Pg. 88-95 Ch. 3 – Sec. 4: Pg. 98-105 Ch. 4 – Sec. 4: Pg. 139-146

2. - Introduction to Atoms Structure of an Atom • Atoms are made of even smaller particles called protons, neutrons, and electrons. • Protons and neutrons are located in the nucleus. • Electrons move rapidly around the nucleus. • Charges: • Protons (+) • Neutrons(0) • Electrons(-)

3. - Introduction to Atoms Models of Atoms • For over two centuries, scientists have created models of atoms in an effort to understand why matter behaves as it does. As scientists have learned more, the model of the atom has changed.

4. - Introduction to Atoms Atoms and Elements • Each element consists of atomsthat differ from the atoms of all other elements. • An element can be identified by the number of protonsin the nucleus of its atoms. • Every atomof an element has the same number of protons. • Because atoms are so small, scientists create models to describe them. • A model may be a diagram, a mental picture, a mathematical statement, or an object that helps explain ideas about the natural world. • Atomic number– number of protons in the nucleus of an atom. • Mass number– the sum of protons and neutrons in the nucleus of an atom. • Atoms with the same number of protons and different number of neutrons are called isotopes.

5. - Introduction to Atoms Isotopes • Atoms of all isotopes of carbon contain six protons, but they differ in the number of neutrons. Carbon-12 is the most common isotope.

6. - Introduction to Atoms More on Atoms • Click the PHSchool.com button for an activity about atoms.

7. - Organizing the Elements Patterns in the Elements • Dimitri Mendeleev, a Russian scientist, discovered a set of patterns that applied to elements. • He noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass. • Atomic mass – the average mass of all the isotopes of that element. • Henry Moseley, a British scientist, discovered atomic number, so now we arrange the periodic table by atomic number. • In the periodic table used today, the properties of elements repeat in each period (row) of the table.

8. - Organizing the Elements Finding Data on Elements • Each square of the periodic table includes an element’s • atomic number, chemical symbol, name, and atomic mass.

9. - Organizing the Elements Periodic Table Activity • Click the Active Art button to open a browser window and access Active Art about the periodic table.

10. - Organizing the Elements Organization of the Periodic Table • The 18 columns of the periodic table reflect a repeating pattern of properties that generally occur across a period.

11. - Organizing the Elements Organization of the Periodic Table • The propertiesof an element can be predicted from its location in the periodic table. • Periods– horizontal rows. • As you move from left to right, properties of the elements change according to pattern. • Groups (families) – vertical columns. • The groups are numbered, from Group 1 on the left to Group 18of the right. • The elements in group have similar characteristics.

12. - Metals Properties of Metals • The physical properties of metals include shininess, malleability, ductility, and conductivity. • A malleable material is one that can be hammered or rolled into flat sheets or other shapes. • A ductile material is one that can be pulled out, or drawn, into long wire. • Conductivityis the ability of an object to transfer heat or electricityto another object.

13. - Metals Properties of Metals • The chemical property, reactivity, is the ease and speed with which an element combines or reacts with other elements or compounds. • The gradual wearing away of a metalelement due to a chemical reaction is corrosion. • The reactivityof metals tends to decrease as you move from left to right across the periodic table.

14. - Metals Metals in the Periodic Table • The metals in Group 1, from lithium to francium, are called the alkali metals. Alkali metals react with atoms of other elements by losing one electron.

15. - Metals Metals in the Periodic Table • Group 2 of the periodic table contains the alkaline earth metals. These elements are not as reactive as the metals in Group 1, but they are more reactive than most other metals.

16. - Metals Melting Points in a Group of Elements • The properties of elements within a single group in the periodic table often vary in a certain pattern. The following graph shows the melting points of Group 1 elements (alkali metals) from lithium to francium.

17. Melting points decrease from lithium to francium. Reading Graphs: As you look at Group 1 from lithium to francium, describe how the melting points of the alkali metals change. - Metals Melting Points in a Group of Elements

18. New element 119 should have a melting point of approximately 25ºC. Predicting: If element number 119 were synthesized, it would fall below francium in Group 1 of the periodic table. Predict the approximate melting point of new element 119. - Metals Melting Points in a Group of Elements

19. None of the alkali metals are liquids at room temperature. Cesium and francium might melt if you could hold them in your hand. Interpreting Data: Room temperature is usually about 22ºC. Human body temperature is 27ºC. Which of the alkali metals are liquids at room temperature? Which might melt if you could hold them in your hand? - Metals Melting Points in a Group of Elements

20. - Metals Metals in the Periodic Table • The transition metals are less reactive than the metals in Groups 1 and 2. • Ex. iron, copper, nickel, silver, and gold

21. - Metals Metals in the Periodic Table • Only some of the elements in Groups 13 through 15 of the periodic table are metals. These metals are not nearly as reactive as those on the left side of the table. • Ex. aluminum, tin, lead

22. - Metals Metals in the Periodic Table • Lanthanidesare soft, malleable, shiny metals with high conductivity. • They are mixed with more common metals to produce alloys, which are a mixture of metal with one other element, usually another metal.

23. - Metals Metals in the Periodic Table • The elements below the lanthanides are called actinides. Many of these elements are so unstablethat they last for only a fraction of a second after they are made.

24. - Metals Synthetic Elements • Elements with atomic numbers higher than 92 are sometimes described as synthetic elements because they are not found naturally on Earth. • Instead, elements that follow uranium are made – or synthesized – when nuclear particlesare forced to crash into one another. • To make even heavier elements (with atomic numbers above 95), scientists use powerful machines called particle accelerators which move atomic nuclei faster and faster until they reach very high speeds and then crash into each other.

25. - Metals Links on Metals • Click the SciLinks button for links on metals.

26. - Nonmetals and Metalloids Properties of Nonmetals • A nonmetalis an element that lacks most of the properties of a metal. • Most nonmetals are poor conductorsof electricity and heat and are reactive with other elements. • Solid nonmetals are dull and brittle. • Many of the nonmetals are common elements on Earth. • Ex. nitrogen, oxygen, carbon, iodine, sulfur, bromine

27. - Nonmetals and Metalloids Properties of Nonmetals • When nonmetals react with metals, one or more electrons move from the metal atoms to the nonmetal atoms.

28. - Nonmetals and Metalloids Families of Nonmetals • Each element in the carbon family has atoms that can gain, lose, or share four electrons when reacting with atoms of other elements.

29. - Nonmetals and Metalloids Families of Nonmetals • Group 15, the nitrogen family, contains two nonmetals: nitrogen and phosphorus. These non-metals usually gain or share three electrons when reacting with atoms of other elements. • Nitrogen is an example of an element that occurs in nature in the form of diatomic molecules, as N2. • A diatomic molecule consists of two atoms.

30. - Nonmetals and Metalloids Families of Nonmetals • Group 16, the oxygen family, contains three nonmetals: oxygen, sulfur, and selenium. These elements usually gain or share two electrons when reacting with atoms of other elements.

31. - Nonmetals and Metalloids Families of Nonmetals • The Group 17, the halogens, are the most reactive nonmetals. Atoms of these elements easily form compounds by sharing or gaining one electron when reacting with atoms of other elements.

32. - Nonmetals and Metalloids Families of Nonmetals • The elements in Group 18 are known as the noble gases. They do not ordinarily form compounds because atoms of noble gases do not usually gain, lose, or share electrons.

33. - Nonmetals and Metalloids Families of Nonmetals • Because the chemical properties of hydrogendiffer very much from those of the other elements, it really cannot be grouped into a family.

34. - Nonmetals and Metalloids The Metalloids • The metalloidshave some characteristics of both metals and nonmetals. The most useful property of the metalloids is their varying ability to conduct electricity. • Semiconductorsare substances that can conduct electricity. • They are used to make computer chips, transistors, and lasers.

35. - Nonmetals and Metalloids Links on Nonmetals • Click the SciLinks button for links on nonmetals.

36. Graphic Organizer Periodic table is made up of organizes Elements Rows Columns called called in order of increasing Atomic number Families Periods or and shows Patterns of properties Groups

37. Radioactivity • Remember…..the number of protons determines the identityof an atom • Ex: Carbon = 6 Oxygen = 8 • Nuclear reaction- reaction involving the particles in the nucleus of an atom • Unlike a chemical reaction which only involves an • atom’s electrons • Isotope- atoms with the same number of protons and different numbers of neutrons • Some are unstable if the nuclei do not hold together well • Radioactive decay- the atomic nuclei of unstable isotopes release fast-moving particles and energy • Ex: Uranium, polonium, radium

38. Radioactivity • Marie Curie, Pierre Curie, and Henri Becquerel studied uraniumafter noticing spontaneous energy release on a photographic plate. • The reaction was occurring within the uranium nuclei • Radioactivity- spontaneous emission of radiation by an unstable atomic nucleus • M. Curie further discovered two new elements which • gave off radioactive energy as well,Polonium and • Radium.

39. Radioactive decay • Natural radioactive decay can produce alpha particles, beta particles, and gamma rays. • Alpha decay- a nucleus loses an alpha particle, which consists of two protons and two neutrons.

40. Radioactive decay • Beta decay- a neutron inside an unstable nucleus changes into a beta particle and a proton. • Beta particle-fast-moving electron given off by a • nucleus during radioactive decay

41. Radioactive decay • Gamma radiation - has no charge and does not cause a change in either the atomic mass or the atomic number. • Consists of high-energy waves.

42. Radioactive decay • The three types of nuclear radiationwere named based on how easily each one could be blocked. • Alpha, beta, and gammaare the first three letters of the Greek alphabet.

43. Radioactive dating • Half-life- the length of time needed for half of the atoms of a sample to decay • Each isotope has its own unique half-life • From the amount of an isotope in a fossil, scientists can calculate how many half-lives have passed since the organism was alive. They are then able to estimate the age of the fossil and the surrounding rock. • Radioactive dating- the process of determining the age of an object using the half-life of one or more radioactive isotopes.

44. Radioactive dating • The half-lives of radioactive isotopes range from a fraction of a second to billions of years.

45. Radioactive dating • Because radioactive isotopes can change into different matter and can give off detectable radiation, they are used in: • Determining the ages of natural materials on Earth • Tracing the steps of chemical reactions and • industrial processes • Diagnosing and treating disease • Providing sources of energy

46. Using Radioactive Isotopes • Tracers– radioactive isotopes that can be followed through the steps of a chemical reaction or industrial process. • Used in studying reactionsin living organisms.

47. Radioactive Tracers Activity • Click the Active Art button to open a browser window and access Active Art about radioactive tracers.

48. Using Radioactive Isotopes • Medicine: • Can make images of the bone, blood vessel or organ affected • Used to destroy unhealthy cells (iodine-131 for thyroid tumors) • Nuclear Power: • Fuel- can provide electric energy

49. Dangers of Radiation • Radiation can: • Penetrate living tissue and • interferewith chemical reactions • in living cells • Cause illness, disease, and even death from overexposure • Protection includes: • Wearing protective clothingand • insulating shields • Properly disposingof wastes

50. Radiation • Click the Video button to watch a movie about radiation.