Science 8th ch5

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  1. Valence electrons
    have the highest energy level and held most loosely
  2. Valence electrons determine
    many properties of that element, including ways in which atom can bond to other atoms
  3. What is the range of valence electrons an atom can have?
    1-8
  4. Electron dot diagram
    each dot stands for one valence electron
  5. How many valence electrons make an atom most stable
    • 8
    • (2 for helium)
  6. Unreactive elements with high valence electrons do not easlily form_____
    compounds
  7. Chemical bond
    force of attraction that holds 2 atoms together as a result of the rearrangement of electrons between them.
  8. Atoms react to make each atom more stable in one of 2 ways
    • 1. the number of valence electrons increases to 8
    • 2. the atom gives up loosely held valence electrons
  9. When atoms bond, one of two things happens witht the electrons
    • 1. electrons may be transferred from one atom to another
    • 2. electrons may be shared between the atoms
    • Both result in a chemical reaction where a new substance forms
  10. Elements within a group or column of the periodic table have what in common?
    the same number of valence electrons
  11. Why do elements within the same group have similar properties
    they have the same number of valence electrons
  12. Noble Gases group # and valence electron #
    • 1. group 18 elements
    • 2. 8 except helium has 2
    • STABLE
  13. Halogens - group # and # of valence electrons
    • 17
    • 7
  14. What elements do halogens react with and how
    easily react with elements that can give up or share electrons
  15. Alkali Metals group # and how many electrons
    • group 1
    • only 1 valence electron
  16. Are alkali metals reactive? Why?
    Very, they can become stable by losing their one valence eletron
  17. Groups of metals and reactivity pattern
    • Groups 1-12
    • reactivity of metals decreases from left to right
    • Groups 1-2: reactivity increases from top to bottom
  18. Green section of periodic table is what, and most act like what at room temp
    • nonmetals
    • gases
  19. Zigzag line between metal and nonmetals and range of electrons
    • Metalloids
    • 3-6
    • can behave as metals or nonmetals
  20. Hydrogen - # of ve's, classification
    Reactive yes or no
    • Only one valence electron
    • Non metal
    • reactive
  21. Most reactive element known
    fluorine, can even combine with noble gases
  22. Ion
    • Atom with electric charge
    • gaining an electron - negative
    • loses electron - positive
  23. Polyatomic ions
    made of more than one atom
  24. Ionic bond
    attraction between 2 oppositely charged ion. Forms as a result of the attraction between positive and negative ions
  25. Ionic compound
    consists of positive and negative ions such as sodium chloride
  26. Chemical formula
    combination of symbols that shows the ratio of elements in a compound.
  27. when ionic compounds form what happens
    • ions come together in a way that balances out the charges on the ions
    • chemical formula for the compound reflects its balance
  28. subscript
    tells ratio of elements in the compound
  29. what comes first in ionic compound name
    positive ion, then negative
  30. Ionic Compounds characteristics in general
    hard brittle crystals that have high melting points and conduct electricity when dissolved in water
  31. crystal
    Orderly 3D arrangement
  32. covalent bond
    chemical bond formed when 2 atoms share electrons
  33. what type of atoms usually form covalent bonds
    nonmetals
  34. what is the force that holds atoms together in cb?
    attraction of each atom's nucleus for the shared pair of electrons
  35. molecule
    neutral group of atoms joined by covalent bonds
  36. double bond
    when 2 atoms share 2  pair of electrons
  37. triple bond
    when atoms share 3 pairs of electrons
  38. molecular compound
    composed of molecules and contains atoms that are covalently bonded
  39. molecular compound characteristics
    • lower melting and boiling points
    • do not conduct electricity when dissolved in water
    • than ionic compounds
  40. polar bond
    covalent bond where electrons are shared unequally
  41. non polar bond
    shared equally
  42. Columns on the periodic table are called
    Groups or families
  43. Columns in periodic table have what characteristic
    Similar propeties
  44. Most metals are NOT
    liquid at room temperature!

    • They ARE
    • malleable
    • reactive
    • magnetic (most are)
    • shiny
    • ductile
    • conductive
  45. the destruction of metal by  reacting to oxygen in the air and forming reddish brown rust is called
    corrosion
  46. Which group contains the most elements?
    Metals
  47. The elements that do not usually form compounds are
    Noble gases
  48. Magnesium bromide is an ionic compound with the chemical formula MgBr2. What does the 2 tell you
    There are 2 bromide ions for every magnesium ions
  49. A chemical bond formed when 2 atoms share electrons is called
    covalent bond
  50. Where are metals located on periodic table
    to the left of zigzag line
  51. How do metals react
    by losing electrons
  52. Are alkali metals ever found uncombined in nature
    No
  53. Properites of Alkaline Metals
    • never uncombined in nature
    • soft shiny
    • very reactive
    • lose one electron
  54. Alkaline Earth Metals
    • Fairly hard
    • Gray white
    • Lose 2 electrons
    • Good conductor
    • Less reactive than group 1 but more than to the right
    • never uncombined
  55. What groups do ionic bonds form between
    metals and nonmetals
  56. covalent compounds form between what group
    Non metals

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Author:
 squirty99
ID:
 185813
Filename:
 Science 8th ch5
Updated:
2012-12-13 03:19:42
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Science 8th ch5 Atoms Bonding
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Science 8th ch5
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