Bell Ringer # 1

1. Bell Ringer # 1 • When ________ runs low, the star begins to die out. • What is the smallest particle of an element? • Name the table that organizes the elements. • Name a stage that a star goes through when dying out. • Name 3 elements produced when a star dies.

2. Introduction to Atoms Chapter 4

3. Development of Atomic Models • The first people to investigate were the ancient Greeks. Around the year 430 B.C.. A Greek philosopher named Democritus proposed that matter is made of small pieces. • These pieces could not be cut into smaller parts. (atomos – means “uncuttable”) • An atom is the smallest particle of an element.

4. Development of Atomic ModelsLOOK and LISTEN • In the 1600s the idea of atoms developed again. • Experiments were performed and the atomic theory began to take shape. • The atomic theory grew as a series of models that developed from experimental evidence. • As more evidence became available, the atomic theory was revised.

5. JOHN DALTON • John Dalton, an English chemist, made an inference that atoms had certain characteristics – smooth, hard ball that could not be broken into smaller pieces.

6. Summary of Dalton’s Ideas • All elements are composed of atoms that cannot be divided. • All atoms of the element are exactly alike and have the same mass. • Atoms of different elements are different and have different mass. • An atom of one element cannot be changed into an atom of a different element. • Atoms cannot be created or destroyed in any chemical change, only rearranged. • Every compound is composed of atoms of different elements combined in a specific ratio.

7. J.J. THOMSON • Thomson Model – 1897 – said that atoms had negatively charged electrons embedded in a positive sphere – • The negatively charged particles are called electrons

8. RUTHERFORD • Rutherford and the Nucleus – 1911 – proposed an atomic model with a positively charged nucleus – these particles were named protons. • An atom was mostly empty space with electrons moving around the nucleus in that space.

9. NEILS BOHR • Bohr’s Model – Niels Bohr, 1913, a Danish scientist showed that electrons could have only specific amounts of energy. • They move in certain orbits (resemble planets orbiting the sun or layers of an onion).

10. Development of Atomic Model • Electrons travel on paths around the nucleus • Proposed structure we use today Neils Bohr

11. A Cloud of Electrons – 1920s – atomic model changed again • Scientists determined that electrons do not orbit the nucleus; electrons can be anywhere in a cloudlike region. • An electron’s movement is related to its energy level.

12. Electron Cloud – look & listen • Surrounds nucleus • Electrons moving on energy levels

13. Electron Configuration – look & listen • The way electrons are placed depends on their energy.

14. The year of 1932, British scientist James Chadwick discovered another particle in the nucleus of atoms, the neutron (electrically neutral). • The modern model describes an atom as consisting of a nucleus that contains protons and neutrons, surrounded by a cloudlike region of moving electrons.

15. Nucleus • Contains protons and neutrons • Has a positive charge • 99.9% mass of atom here

16. Particle Charges • In an atom, the number of protons equals the number of electrons • number of neutrons in an atoms does not have to equal the number of protons. • Neutrons do not affect the charge of an atom. Why?

17. Comparing Particle Masses – • Protons and Neutrons have about the same mass • The protons and neutrons make up nearly all the mass of an atom. • The mass of protons and electrons are not equal – it takes almost 2000 electrons to equal the mass of just one proton!

18. Scale and Size of Atoms – look & listen • Since atoms are so small that they are very difficult to imagine, models are helpful in learning about them. • The tiniest visible speck of dust may contain 10 million billion atoms!

19. Atomic Number • Every atom of an element has the same number of protons… this number is the atomic number. • The atomic number identifies an element • it is like the atom’s fingerprint.

20. Isotopes and Mass Number • Isotopes are atoms with differing numbers of protons and neutrons • An isotope is identified by its massnumber; • Mass number = protons + neutrons

21. Warm up 8/19/15 Use Schoology if you have a device. (Write questions) • The term Rutherford gave to the positively charged particles in the nucleus of an atom was _______. • True or false: Atoms are the smallest particles of matter. • The atomic model of ______ resembled planets orbiting the sun. • True or false: Since the 1930s, the model of the atom has changed a great deal. • An element can be identified by the number of ____ in the nucleus of its atoms

22. Open binder and find the Guided Reading we completed yesterday, Ch. 4 Sec. 1 • Use it to complete the quiz… turn quiz in • Finish Sec. 1 Assessment p. 108 • Atom Model Making Activity • Fold paper hamburger and then hamburger • On cover, write a title, name, date • Decorate if wanted after labeling inside but before construction • Top inside flap • Write the following parts and give 2 for each: • Nucleus • Proton • Neutrons • Electron Cloud • Construct and glue your model on lower inside half & LABEL or MAKE A KEY when done

23. JOURNAL WRITING • Write a well-developed paragraph explaining the parts of an atom and the modern model of an atom

24. Organizing the Elements Section 2

25. Mendeleev’s Work • Mendeleev wrote each element’s melting point (M.P.), density, and color on individual cards. • He also included the element’s atomic mass and the number of chemical bonds it could form. • Atomic massis the average mass of all the isotopes of an element.

26. Mendeleev’s Work • Pattern of properties appeared when he arranged the elements in order of increasing atomic mass. • He moved a few of his element cards into groups where the elements did have similar properties. • After arranging all 63 elements, three blanks existed. • He predicted the discovery of those elements and their properties

27. The Modern Periodic Table • The properties of the elements repeat in each period—or row of the table • New elements were added as they were discovered. • In 1913, Henry Moseley, a British scientist, discovered a way to measure the positive charge on an atom’s nucleus.

28. Let’s Review • What properties do silver and copper share? • What information did Mendeleev use to try to find a pattern in the elements?

29. Organization of the Periodic Table • The properties of an element can be predicted from its location in the periodic table. • The table is organized in horizontal rows called periods. • The left side of the table are highly reactive metals; less reactive metals are in the middle of the table. • There are 18 vertical columns, or groups They are sometimes known as families.

30. Reading an Element’s Square In this book, each square includes the element’s • atomic number, chemical symbol, name, and atomic mass. • abbreviation of the element’s name in English • some elements are abbreviations of their Latin names, gold = aurum, iron = ferrum • atomic mass is an average because most elements consist of a mixture of isotopes.

31. How Elements Form in Stars • The sun is made mostly of one element—hydrogen • It is plasma and free of electrons with a nuclei of atoms that have been stripped of electrons. • Atomic nuclei contain protons which are positive. • Plasma are positively charged nuclei and usually repel one another. • In stars, the pressure is so high that nuclei are squeezed close together and collide.

32. How Elements Form in Stars • Nuclear fusion is a process in which two atomic nuclei combine, forming a larger nucleus and releasing huge amounts of energy. • Nuclear fusion occurs in stars on a huge scale • In the sun, different isotopes of hydrogen fuse and the energy produced is the most important source of energy in the sun. • In more massive stars, fusion continues until the core is almost all iron.

33. How Elements Form in Stars • A supernova is 1 billion degrees Celsius. • It provides enough energy to create the heaviest elements. • These elements are blown in space as stardust

34. Check Up • Why is the atomic mass of an element an average? • Where are elements heavier than iron produced? • What pattern did Mendeleev discover when he arranged the elements? • What is the process that produces elements in stars? • List three kinds of information about an element that can be found in a square of the periodic table.

35. metal ductile malleable reactivity conductivity corrosion alkali metal alkaline earth metal transition metal • particle accelerator nonmetal diatomic molecule noble gas metalloid semiconductor halogen Vocabulary Sections 3 & 4

36. Bell Ringer # 2 1. A chart of the elements showing the repeating pattern of their properties is called the ____________________. 2. Each horizontal row in the periodic table iscalled a (n) ________________. 3.True or False: Across a period from left toright, the properties of elements changeaccording to a pattern. 4.The modern periodic table is now arranged according to _____________ 5. Mendeleev’s periodic table had ____ blank spaces left in it, which represented elements that had not yet been discovered.

37. Bell Ringer # 2 1. A chart of the elements showing the repeating pattern of their properties is called the ____________________. 2. Each horizontal row in the periodic table iscalled a (n) ________________. 3.True or False: Across a period from left toright, the properties of elements changeaccording to a pattern. 4.The modern periodic table is now arranged according to _____________ 5. Mendeleev’s periodic table had ____ blank spaces left in it, which represented elements that had not yet been discovered.

38. Bell Ringer #3 • Circle the letter of each term that refers to elements in a column of the periodic table. a. Period b. Family c. Group d. Symbol 2. Circle the letter of the statement that is true about elements in each group. a. They all have the same atomic mass. b. They all have similar characteristics. c. They all have similar atomic numbers. d. They all have the same chemical symbol. • What does nuclear fusion create inside stars? • What are the two most important alkali metals? • What are the two most common alkaline earth metals?

39. Bell Ringer #3 • Circle the letter of each term that refers to elements in a column of the periodic table. a. Period b. Family c. Group d. Symbol 2. Circle the letter of the statement that is true about elements in each group. a. They all have the same atomic mass. b. They all have similar characteristics. c. They all have similar atomic numbers. d. They all have the same chemical symbol. • What does nuclear fusion create inside stars? • What are the two most important alkali metals? • What are the two most common alkaline earth metals?

40. Metals Section 3

41. Properties of Metals • Properties of Metals • PHYSICAL PROPERTIES: • shininess • malleability - material that can be hammered or rolled into flat sheets and other shapes • ductility - can be pulled out, or drawn, into a long wire • conductivity- ability of an object to transfer heat or electricity to another objects.

42. Check Up • What are three physical properties of metals? • malleability • shininess • ductility • conductivity

43. Properties of Metals • Chemical Properties: • Reactivity- ease and speed with which an element combines, or reacts, with other elements and compounds • sodium (Na) reacts strongly • gold (Au) and platinum (Pt) are valued for their lack of reactivity

44. Metals in the Periodic Table Alkali Metals • Reactivity of metals tend to decrease as you move from left to right across the periodic table. • They are so reactive that they are never found as uncombined elements in nature – always a compound. • Two most important alkali metals are sodium and potassium.

45. Alkaline Earth Metals • Alkaline earth metals are fairly hard, gray-white, and a good conductor of electricity. • They are never found uncombined in nature • The two most common are magnesium and calcium • Mix magnesium with aluminum for ladders, calcium for bones, teeth, and muscles.

46. Are You Listening? • Turn to the person beside you • Each of you say 3 facts you know about alkali metals and alkaline earth metals.

47. Transition Metals • Transition metals are most of the familiar metals, such as iron, copper, nickel, silver, and gold. • Most are hard and shiny. • They are good conductors of electricity. • The lack of reactivity is why gold coins exist that are 100s of years old. • Iron makes hemoglobin, which carries your blood through your body.

48. Metals in Mixed Groups • In groups 13 through 15, of the periodic table, only some are metals. • These metals are not nearly as reactive as those on the left side of the table. • The most familiar of these metals are aluminum, tin, and lead.

49. Lanthanides • Lanthanides are two rows of elements below the main part of the periodic table • They are soft, malleable, shiny metals with high conductivity • They are mixed with more common metals to make alloys • An alloy is a mixture of a metal with at least one other element.

50. Actinides • Actinides are elements below the lanthanides • Only a few occur in nature. • Others are made in a lab • The nuclei of these elements are very unstable, meaning that they break apart very quickly into smaller nuclei • Uranium is used to produce energy in nuclear power plants