full transcript

From the Ted Talk by MaruĊĦa Brada: The science of snowflakes

Unscramble the Blue Letters

If you ever find yourself gazing at falling snow, why not catch a few snowflakes on your glove and examine their saphes? You might noitce that they look symmetrical, and if you look closely, you'll see they have six sides. You could say a snowflake is simply frozen water, but crmpaoe one with an ice cube from the frzeeer, and you'll realize they're very different things. Unlike ice cubes, formed when liquid freezes into a solid, snowflakes form when water voapr turns straight into ice. But that still doesn't elpaxin why snowflakes have six sides. To understand that, we need to dvele deeper into the physics of water. Water is made out of two hydrogen atoms and one oxygen atom. A single water molecule thus has ten protons and ten electrons, eight from oxygen and one from each hydrogen atom. The two electrons from oxygen's outer shlel are shared with two electrons from both hydrogens as they bond together, and the remaining four outer shell electrons from oxygen form two pairs. We call the bonds between these atoms covalent bonds. The pairs of electrons are all netagleviy charged. Similar charges repel, so they tend to stay as far away from each other as possible. The pairs form four elorectn clouds, two of which are where the hoegydrn and oxygen share electrons. The repulsion between the unnobedd pairs is even stronger than repulsion between the shared prias, so the two hydrogens get pushed a little further to an agnle of 104.5 deeregs. The wtaer molecule as a whole is electrically neutral, but oxygen gets a lreagr share of eceortlns, making it slightly negative and the hydrogens slightly positive. Due to its negative charge, the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule. And so a weak bond between the two molecules, called a hydrogen bond, is formed. When water freezes, this bonding oucrcs on repeat, utlealtimy forming a hexagonal structure due to the angle between hydrogens and oxygen within each mluecloe. This is the seed of a snowflake, and it retains a hexagonal shape as it grows. As the snowflake moves through the air, water vapor molecules scitk to the six sharp edges and expand the snowflake outwards, bit by bit. A snowflake's developing sahpe depends on atmospheric conditions, like humidity and temperature. As a snowflake falls, changes in weather conditions can affect how it grows, and even small differences in the paths two sklnawfoes take will differentiate their shapes. However, since conditions at the six sharp egeds of one snowflake are smiilar, a syrmiemtc salnwfkoe can grow. Weather conditions affect snow on the gronud, as well. Warmer ground tratempueers produce a wetter snow that is easier to pack because liquid water mecluelos help snowflakes stick to each other. Melted snow also plays a critical role in another wintry activity, skiing. Completely dry snow is very dlufiifct to ski on because there's too much frcoitin between the jagged snowflakes and the ski surface. So what's happening is that as skis move, they rub the surface of the snow and warm it up, cineartg a thin layer of water, which helps them slide along. So technically, it's not really snow skiing, but water skiing. But it is true that no matter how hard you look, you're almost definitely not going to find two identical snowflakes, and that's a mystery that scientists are still trying to solve, though we know that it has to do with the many possible branching points in snowflake fmooitarn, and the differences in tumrtrpeaee and humidity, and while we wait for the answer, we can enjoy watching these tiny fractals falling from the sky.

Open Cloze

If you ever find yourself gazing at falling snow, why not catch a few snowflakes on your glove and examine their ______? You might ______ that they look symmetrical, and if you look closely, you'll see they have six sides. You could say a snowflake is simply frozen water, but _______ one with an ice cube from the _______, and you'll realize they're very different things. Unlike ice cubes, formed when liquid freezes into a solid, snowflakes form when water _____ turns straight into ice. But that still doesn't _______ why snowflakes have six sides. To understand that, we need to _____ deeper into the physics of water. Water is made out of two hydrogen atoms and one oxygen atom. A single water molecule thus has ten protons and ten electrons, eight from oxygen and one from each hydrogen atom. The two electrons from oxygen's outer _____ are shared with two electrons from both hydrogens as they bond together, and the remaining four outer shell electrons from oxygen form two pairs. We call the bonds between these atoms covalent bonds. The pairs of electrons are all __________ charged. Similar charges repel, so they tend to stay as far away from each other as possible. The pairs form four ________ clouds, two of which are where the ________ and oxygen share electrons. The repulsion between the ________ pairs is even stronger than repulsion between the shared _____, so the two hydrogens get pushed a little further to an _____ of 104.5 _______. The _____ molecule as a whole is electrically neutral, but oxygen gets a ______ share of _________, making it slightly negative and the hydrogens slightly positive. Due to its negative charge, the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule. And so a weak bond between the two molecules, called a hydrogen bond, is formed. When water freezes, this bonding ______ on repeat, __________ forming a hexagonal structure due to the angle between hydrogens and oxygen within each ________. This is the seed of a snowflake, and it retains a hexagonal shape as it grows. As the snowflake moves through the air, water vapor molecules _____ to the six sharp edges and expand the snowflake outwards, bit by bit. A snowflake's developing _____ depends on atmospheric conditions, like humidity and temperature. As a snowflake falls, changes in weather conditions can affect how it grows, and even small differences in the paths two __________ take will differentiate their shapes. However, since conditions at the six sharp _____ of one snowflake are _______, a _________ _________ can grow. Weather conditions affect snow on the ______, as well. Warmer ground ____________ produce a wetter snow that is easier to pack because liquid water _________ help snowflakes stick to each other. Melted snow also plays a critical role in another wintry activity, skiing. Completely dry snow is very _________ to ski on because there's too much ________ between the jagged snowflakes and the ski surface. So what's happening is that as skis move, they rub the surface of the snow and warm it up, ________ a thin layer of water, which helps them slide along. So technically, it's not really snow skiing, but water skiing. But it is true that no matter how hard you look, you're almost definitely not going to find two identical snowflakes, and that's a mystery that scientists are still trying to solve, though we know that it has to do with the many possible branching points in snowflake _________, and the differences in ___________ and humidity, and while we wait for the answer, we can enjoy watching these tiny fractals falling from the sky.

Solution

  1. negatively
  2. degrees
  3. angle
  4. delve
  5. water
  6. similar
  7. unbonded
  8. snowflake
  9. compare
  10. shell
  11. ground
  12. difficult
  13. electron
  14. hydrogen
  15. freezer
  16. vapor
  17. edges
  18. molecule
  19. temperatures
  20. larger
  21. molecules
  22. stick
  23. ultimately
  24. explain
  25. shapes
  26. shape
  27. creating
  28. friction
  29. formation
  30. notice
  31. symmetric
  32. temperature
  33. snowflakes
  34. pairs
  35. electrons
  36. occurs

Original Text

If you ever find yourself gazing at falling snow, why not catch a few snowflakes on your glove and examine their shapes? You might notice that they look symmetrical, and if you look closely, you'll see they have six sides. You could say a snowflake is simply frozen water, but compare one with an ice cube from the freezer, and you'll realize they're very different things. Unlike ice cubes, formed when liquid freezes into a solid, snowflakes form when water vapor turns straight into ice. But that still doesn't explain why snowflakes have six sides. To understand that, we need to delve deeper into the physics of water. Water is made out of two hydrogen atoms and one oxygen atom. A single water molecule thus has ten protons and ten electrons, eight from oxygen and one from each hydrogen atom. The two electrons from oxygen's outer shell are shared with two electrons from both hydrogens as they bond together, and the remaining four outer shell electrons from oxygen form two pairs. We call the bonds between these atoms covalent bonds. The pairs of electrons are all negatively charged. Similar charges repel, so they tend to stay as far away from each other as possible. The pairs form four electron clouds, two of which are where the hydrogen and oxygen share electrons. The repulsion between the unbonded pairs is even stronger than repulsion between the shared pairs, so the two hydrogens get pushed a little further to an angle of 104.5 degrees. The water molecule as a whole is electrically neutral, but oxygen gets a larger share of electrons, making it slightly negative and the hydrogens slightly positive. Due to its negative charge, the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule. And so a weak bond between the two molecules, called a hydrogen bond, is formed. When water freezes, this bonding occurs on repeat, ultimately forming a hexagonal structure due to the angle between hydrogens and oxygen within each molecule. This is the seed of a snowflake, and it retains a hexagonal shape as it grows. As the snowflake moves through the air, water vapor molecules stick to the six sharp edges and expand the snowflake outwards, bit by bit. A snowflake's developing shape depends on atmospheric conditions, like humidity and temperature. As a snowflake falls, changes in weather conditions can affect how it grows, and even small differences in the paths two snowflakes take will differentiate their shapes. However, since conditions at the six sharp edges of one snowflake are similar, a symmetric snowflake can grow. Weather conditions affect snow on the ground, as well. Warmer ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes stick to each other. Melted snow also plays a critical role in another wintry activity, skiing. Completely dry snow is very difficult to ski on because there's too much friction between the jagged snowflakes and the ski surface. So what's happening is that as skis move, they rub the surface of the snow and warm it up, creating a thin layer of water, which helps them slide along. So technically, it's not really snow skiing, but water skiing. But it is true that no matter how hard you look, you're almost definitely not going to find two identical snowflakes, and that's a mystery that scientists are still trying to solve, though we know that it has to do with the many possible branching points in snowflake formation, and the differences in temperature and humidity, and while we wait for the answer, we can enjoy watching these tiny fractals falling from the sky.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
water vapor 2
water molecule 2
outer shell 2
sharp edges 2
weather conditions 2

Important Words

  1. activity
  2. affect
  3. air
  4. angle
  5. answer
  6. atmospheric
  7. atom
  8. atoms
  9. attracted
  10. bit
  11. bond
  12. bonding
  13. bonds
  14. branching
  15. call
  16. called
  17. catch
  18. charge
  19. charged
  20. charges
  21. closely
  22. clouds
  23. compare
  24. completely
  25. conditions
  26. covalent
  27. creating
  28. critical
  29. cube
  30. cubes
  31. deeper
  32. degrees
  33. delve
  34. depends
  35. developing
  36. differences
  37. differentiate
  38. difficult
  39. dry
  40. due
  41. easier
  42. edges
  43. electrically
  44. electron
  45. electrons
  46. enjoy
  47. examine
  48. expand
  49. explain
  50. falling
  51. falls
  52. find
  53. form
  54. formation
  55. formed
  56. forming
  57. fractals
  58. freezer
  59. freezes
  60. friction
  61. frozen
  62. gazing
  63. glove
  64. ground
  65. grow
  66. grows
  67. happening
  68. hard
  69. helps
  70. hexagonal
  71. humidity
  72. hydrogen
  73. hydrogens
  74. ice
  75. identical
  76. jagged
  77. larger
  78. layer
  79. liquid
  80. making
  81. matter
  82. melted
  83. molecule
  84. molecules
  85. move
  86. moves
  87. mystery
  88. negative
  89. negatively
  90. neutral
  91. notice
  92. occurs
  93. outer
  94. outwards
  95. oxygen
  96. pack
  97. pairs
  98. paths
  99. physics
  100. plays
  101. points
  102. positive
  103. produce
  104. protons
  105. pushed
  106. realize
  107. remaining
  108. repeat
  109. repel
  110. repulsion
  111. retains
  112. role
  113. rub
  114. scientists
  115. seed
  116. shape
  117. shapes
  118. share
  119. shared
  120. sharp
  121. shell
  122. sides
  123. similar
  124. simply
  125. single
  126. ski
  127. skiing
  128. skis
  129. sky
  130. slide
  131. slightly
  132. small
  133. snow
  134. snowflake
  135. snowflakes
  136. solid
  137. solve
  138. stay
  139. stick
  140. straight
  141. stronger
  142. structure
  143. surface
  144. symmetric
  145. symmetrical
  146. technically
  147. temperature
  148. temperatures
  149. ten
  150. tend
  151. thin
  152. tiny
  153. true
  154. turns
  155. ultimately
  156. unbonded
  157. understand
  158. vapor
  159. wait
  160. warm
  161. warmer
  162. watching
  163. water
  164. weak
  165. weather
  166. wetter
  167. wintry