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Elements

Elements. An element is either classified as a metal, nonmetal or metalloid. The classification depends on the elements location on the periodic table. Metals are in pink. Nonmetals are in lime green . Metalloids are in white . B. Si. As. Ge. Sb. Te. Po. At.

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Elements

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  1. Elements An element is either classified as a metal, nonmetal or metalloid. The classification depends on the elements location on the periodic table.

  2. Metals are in pink. Nonmetals are in lime green. • Metalloids are in white. B Si As Ge Sb Te Po At

  3. Metals are in yellow. Elements

  4. Nonmetals are in purple. Elements

  5. Metalloidsare in green. Elements

  6. Properties of Metals Metals are elements that have luster, conduct heat and electricity, and usually bend without breaking. Metals are also ductile (can be drawn out into a wire).

  7. All metals except mercury (Hg) are solids at room temperature; in fact, most have extremely high melting points and high boiling points. Properties of Metals

  8. A metal’s reactivity is its ability to react with another substance. Metals in the first and second column of the periodic table are more reactive than other metals. Properties of Metals

  9. Although the majority of the elements in the periodic table are metals, many nonmetals are abundant in nature. Properties of Nonmetals

  10. Most nonmetals don’t conduct electricity, are much poorer conductors of heat than metals, and are brittle when solid. Many are gases at room temperature; those that are solids lack the luster of metals. Properties of Nonmetals

  11. Their melting points tend to be lower than those of metals. Fluorine is the most reactive nonmetal. Properties of Nonmetals

  12. Metalloidshave some chemical and physical properties of metals and other properties of nonmetals. In the periodic table, the metalloids lie along the border between metals and nonmetals. Properties of Metalloids

  13. Properties of Metalloids

  14. Some metalloids such as silicon, germanium (Ge), and arsenic (As) are semiconductors. A semiconductoris an element that does not conduct electricity as well as a metal, but does conduct slightly better than a nonmetal. Properties of Metalloids

  15. Objectives PSc.2.1.4 Interpret the data presented in the Bohr model diagrams and dot diagrams for atoms and ions of elements 1 through 18.

  16. Modern View of the Atom The atom has two regions and is 3-dimensional. The nucleus is at the center and contains the protons and neutrons.

  17. The electron cloud is the region where you might find an electron and most of the volume of an atom. Modern View of the Atom

  18. Subatomic Particles Relative mass Relative mass Name Symbol Symbol Charge Charge Electron e- -1 1/2000 p+ +1 1 Proton Neutron n0 0 1

  19. Atomic Number The atomic number of an element is the number of protons in the nucleus of an atom of that element. The number of protons determines identity of an element, as well as many of its chemical and physical properties.

  20. Mass Number The sum of the protons and neutrons in the nucleus is the mass number of that particular atom.

  21. Symbols Elements can be represented by using the symbol of the element, the mass number and the atomic number. X Mass number Atomic number • The mass number is the atomic mass rounded to a whole number.

  22. Problem Determine the following for the fluorine atom depicted below. (9) • number of protons 19 F • number of neutrons (10) 9 • number of electrons (9) • atomic number (9) • e) mass number (19)

  23. Problem Determine the following for the bromine atom depicted below. (35) • number of protons 80 Br • number of neutrons (45) 35 • number of electrons (35) • atomic number (35) • e) mass number (80)

  24. Problem 78 Se 34 • If an element has an atomic number of 34 and a mass number of 78 what is the (34) • number of protons • number of neutrons (44) • number of electrons (34) • d) complete symbol

  25. Problem 231 Pa 91 • If an element has 91 protons and 140 neutrons what is the (91) • atomic number • mass number (140) • number of electrons (91) • d) complete symbol

  26. Cations A cation is a positive ion. It is formed when an atom loses one or more electrons. Ca2+

  27. Anions An anion is a negative ion. It is formed when an atom gains one or more electrons. Cl1-

  28. Problem Determine the following for the chlorine ion depicted below. (18) • number of neutrons 35 Cl1- • number of electrons (18) 17 • number of protons (17) • mass number (35) • e) atomic number (17)

  29. Problem Determine the following for the aluminum ion depicted below. (27) • mass number 27 Al3+ • number of electrons (10) 13 • atomic number (13) • number of protons (13) • e) number of neutrons (14)

  30. In 1910, J.J. Thomson discovered that neon consisted of atoms of two different masses. Isotopes

  31. Atoms of an element that are chemically alike but differ in mass are called isotopes of the element. Isotopes

  32. Consider the isotope of carbon that has a mass number of 14. The following are different ways to write symbols for this isotope. Isotopic Notation 14C 6 Carbon-14 14C C-14

  33. The Bohr Model of the Atom Niels Bohr, a young Danish physicist working in Rutherford’s laboratory in 1913, suggested that the single electron in a hydrogen atom moves around the nucleus in only certain allowed circular orbits.

  34. The atom looked like a miniature solar system. The nucleus is represented by the sun, and the electrons act like the planets. The Bohr Model of the Atom

  35. The Bohr Model of the Atom Nucleus Electron Orbit Energy Levels

  36. The orbits are circular and are at different levels. Amounts of energy separate one level from another. The Bohr Model of the Atom

  37. Bohr Diagrams • Find your element on the periodic table. • Determine the number of electrons • This is how many electrons you will draw.

  38. Find out which period (row) your element is in. • Elements in the 1st period have one energy level. • Elements in the 2nd periodhave two energy levels, and so on. Bohr Diagrams

  39. C Bohr Diagrams Draw a nucleus with the element symbol inside. Carbon is in the 2nd period, so it has two energy levels, or shells. Draw the shells around the nucleus.

  40. C Bohr Diagrams Add the electrons. Carbon has 6 electrons. The first shell can only hold 2 electrons.

  41. C Bohr Diagrams The second shell can only hold 8 electrons. The third shell can only hold 18 electrons.

  42. C Bohr Diagrams Since you have 2 electrons already drawn, you need to add 4 more. These go in the 2nd shell. Add one at a time -starting on the right side and going counter-clockwise.

  43. Bohr Diagrams Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  44. H Bohr Diagrams 1 electron Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  45. He Bohr Diagrams 2 electrons Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  46. Bohr Diagrams O2- 10 electrons Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  47. Bohr Diagrams Mg2+ 10 electrons Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  48. Ne Bohr Diagrams 10 electrons Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

  49. Bohr Diagrams Ar 18 electrons Try the following elements on your own: • H • He • O2- • Mg2+ • Ne • Ar

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