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Atoms and Elements: Are they Related?

Atoms and Elements: Are they Related?. Fall 2011. ATOMS. ALL MATTER IS MADE OF ATOMS Definition: ATOMS ARE THE SMALLEST PIECE OF MATTER and CANNOT BE BROKEN DOWN INTO A SIMPLER SUBSTANCE. ATOMS HAVE 3 BASIC PARTS (Subatomic Particles) PROTONS NEUTRONS ELECTRONS.

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Atoms and Elements: Are they Related?

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  1. Atoms and Elements: Are they Related? Fall 2011

  2. ATOMS • ALL MATTER IS MADE OF ATOMS • Definition: ATOMS ARE THE SMALLEST PIECE OF MATTER and CANNOT BE BROKEN DOWN INTO A SIMPLER SUBSTANCE.

  3. ATOMS HAVE 3 BASIC PARTS (Subatomic Particles) • PROTONS • NEUTRONS • ELECTRONS

  4. PROTONS(POSITIVE CHARGE) • ARE FOUND IN THE NUCLEUS AND MAKE UP MOST OF THE MASS OF THE ATOM. • VERY IMPORTANT!!! The number of protons an atom has tells you what kind of atom it is!!!!

  5. The Atomic Number is the number of Protons Pg. 158

  6. NEUTRONS(NO CHARGE) • ARE FOUND IN THE NUCLEUS • MAKE UP PART OF THE MASS OF THE ATOM

  7. Finding the Number of Neutrons for an Atom • The protons and neutrons make up the mass of an atom. • If you know the protons (atomic number) then you can find the number of neutrons by subtracting the atomic mass from the # of protons (atomic number). atomic mass - # of protons = # of neutrons

  8. Isotopes • Atoms of the same element that have a different number of neutrons. EX: Carbon Carbon-12 Carbon-13 Carbon-14

  9. Isotopes & Radioactive Decay • Atoms are most stable when they have the same number of Pro/Neu in the nucleus… • So, having more neutrons causes atom to be unstable & “repulsion” builds up. • Nucleus becomes more stable when the extra particles are released & energy is given off. • RD is the release of extra nuclear particles & energy.

  10. ELECTRONS(NEGATIVE CHARGE - ) • FOUND IN THE ELECTRON SHELL (cloud) ORBITING THE NUCLEUS. • TAKES UP MOST OF THE SPACE IN AN ATOM. • The # of electrons = the # of protons

  11. Valence Electrons • Outermost electron(s) in the cloud/shell • 8 is the magic number!!!!!! (octet rule)

  12. Ions • Atom where the total number of electrons does not equal the total number of protons (atom will have a pos or neg charge) • Cation= pos (loss of e-) • Anion=neg (gain of e-) • EX: Fe2+, Al3+, O2-

  13. Label the atom below on your packet! What type of atom is this? How do you know?

  14. Let’s Break for Questions??? • How many protons should Hydrogen have? • How about Oxygen? • Which particles are located in the nucleus of an atom? • Where are the electrons located?

  15. Atomic Size -A typical atom is about one ten-billionth of a meter in diameter. (THAT’S REALLY, REALLY SMALL AND WHY WE CAN’T SEE THEM WITH A REGULAR MICROSCOPE) -ATOMIC MASS = Protons + Neutrons. -Most of the atomic mass comes from the nucleus. -Electrons weigh very little. That is why they do not add to the mass of the atom. -They DO contribute to the SIZE.

  16. Isotopes & Mass Number • So if protons and neutrons contribute to mass, if we have a different number of neutrons, will the mass be affected? • EX: since C-14 has 8 neutrons, the mass number is 14amu instead of 12amu (C-12).

  17. Discovery of the Atom (pg. 80) By the early 1800’s, John Dalton proposed that all substances are made up of atoms. In 1898, J.J. Thomson, proposed that atoms are made up of smaller parts. In 1911, Ernest Rutherford, proposed that atoms have electrons and a positively charged nucleus.

  18. Dalton’s Atomic Theory • All matter is made of atoms. Atoms are indivisible and indestructible. • 2) All atoms of a given element are identical in mass and properties • 3) Compounds are formed by a combination of two or more different kinds of atoms. • 4)A chemical reaction is a rearrangement of atoms.

  19. Niels Bohr’s model of the atom • Electrons revolved around the nucleus in circular paths called orbits.

  20. Current Atomic Theory: Electron Cloud Model Electrons travel in regions of various thicknesses called clouds.

  21. ELEMENTS • DEFINITION: PURE SUBSTANCES MADE OF ONLY 1 KIND OF ATOM. • ARE THE BUILDING BLOCKS OF MATTER. • CANNOT BE BROKEN DOWN INTO A SIMPLER SUBSTANCE. • HAVE THEIR OWN UNIQUE SET OF PROPERTIES THAT NO OTHER ELEMENT HAS.

  22. ELEMENTS • There are 92 naturally occurring elements on the periodic table. This means they are in nature and not made in a laboratory by scientists. • As of this year (2011) there are 118 confirmed elements. There are 4 more under investigation and scientific testing.

  23. Let’s Stop for Questions! • What type of atoms make up the element Lithium? Carbon? Sodium?

  24. ELEMENTS ARE MADE OF ONLY 1 KIND OF ATOM. • SOME COMMON ELEMENTS • HYDROGEN (H), HELIUM (He), OXYGEN (0), • Notice that the first letter is capital and the next letter is lower case.

  25. Atoms and Elements Activity • As a group, look at the food labels on the items at your table. Make a list of the items in the left hand side column and in the right hand side column make a list of any elements found in that substance. • You may use your periodic table to help you identify the elements.

  26. The food item would be: Cooked Ham What are the elements that are found on this food label?

  27. QUESTIONS???? • What are the most commonly occurring elements in the food labels? • What items seemed to have the most amount of elements in them? • Can you predict what that means about the food item? • Why do you think the baby formula has such a variety of elements? • Can you predict what the other items on the food label are if they are not elements?

  28. Wrap UpUse your dry erase boards to write answers and hold them high!!! • Protons have what charge? • Electrons have what charge? • Which parts of an atom make up the mass of the atom? • Elements are made up of? • The element lead is made up of what kind of atoms?

  29. Periodic Table • The periodic table is an organized table of each element. • Each box gives information about each type of element found on Earth.

  30. Dmitri Mendeleev (1869) In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. The periodic table is base on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley ( England,1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized. http://www.chem.msu.su/eng/misc/mendeleev/welcome.html

  31. ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE ACCORDING TO ATOMIC NUMBER.

  32. ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE OF ELEMENTS ACCORDING TO THEIR SIMILAR CHARACTERISTICS • 3 major groups: metals, nonmetals and metalloids • See pg. 57 in book

  33. Element Info in Each Box Atomic weight Atomic Number Symbol Name

  34. Information from the periodic table Atomic Number- Number of Protons in an atom Silver = 47 protons

  35. Iron- Fe (Ferrum) Lead- Pb (Plumbum) • Elements & their symbols • SOME COMMON ELEMENTS • HYDROGEN (H), HELIUM (He), OXYGEN (0), • Notice that the first letter is capital and the next letter is lower case. Gold- Au (Aurum)

  36. Arrangement of the Periodic table Periods– Rows are called periods. The elements in these rows change conductivity and number of electrons as you move across the table. Groups – Columns are called groups or families. These elements have the same properties because of the number of electrons.

  37. How is the Periodic Table Organized? Periods Even though they skip some squares in between, all of the rows go left to right. When you look at a periodic table, each of the rows is considered to be a different period

  38. Across the Periodic Table • Periods: Are arranged horizontally across the periodic table (rows 1-7) • These elements have the same number of valence shells. 2nd Period 6th Period

  39. When a column goes from top to bottom, it's called a group or family. Groups Groups are often called families because these elements seem to be related. **Elements in the same group show similarities in their chemical and physical properties.

  40. Alkali Family: 1 e- in the valence shell Halogen Family: 7 e- in the valence shell Down the Periodic Table • Family:Are arranged vertically down the periodic table (columns or group, 1- 18 or 1-8 A,B) • These elements have the same number electrons in the outer most shells, the valence shell.

  41. Reading the Periodic Table: Classification • Nonmetals, Metals, Metalloids, Noble gases

  42. Halogen Alkali Noble Gas Alkaline (earth) Chalcogens Transition Metals Infamous Families of the Periodic Table • Notable families of the Periodic Table and some important members:

  43. Alkali Group • -Group #1 • -1 valence electron in outer shell • -very reactive with water & other elements • -low densities & melting points

  44. Alkaline Earth Group • -Group #2 • -2 valence electrons in outer shell • -very reactive but not as much as alkali • -denser, harder & higher melting points

  45. Transition Metals • -Groups 3-12 • -Valence electrons vary • -Usually found combined with other elements • -higher melting points, good conductors

  46. Halogen Group • -Group #17 • -7 valence electrons in outer shell • -most combined to make salts (salt formers) • -most are non-metals

  47. Noble Gas Group • -Group # 18 • -8 valence electrons in outer shell (the happy gases! ) • -NOT REACTIVE

  48. Periodic Table: Metallic arrangement • Layout of the Periodic Table: Metals vs. nonmetals Nonmetals Metals

  49. Summary • Periodic Table: Map of the Building block of matter • Type: Metal, metalloid and Nonmetal • Groupings: Representative or main, transition and Lanthanide/Actanides • Family: Elements in the same column have similar chemical property because of similar valence electrons • Alkali, Alkaline, halogens, noble gases • Period: Elements in the same row have valence electrons in the same shell.

  50. The Periodic Table Of Elements Elements are classified: *Metals *Nonmetals *Metalloids Xenon Scandium

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