TedTest

From the Ted Talk by Maruša 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 eximnae 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 spmily 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 luiiqd freezes into a solid, snowflakes form when water vapor turns straight into ice. But that still doesn't elxaipn 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 mueollce 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 eotnrelcs from both hydrogens as they bond together, and the remaining four outer shell electrons from oxygen form two pairs. We call the bdons between these aotms 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 wtear molecule as a whole is electrically neutral, but ogyxen gets a lgearr share of electrons, making it slightly negative and the hydrogens slightly positive. Due to its negative crhgae, 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 hyrogedn bond, is formed. When water freezes, this bonding occurs on repeat, ultimately forming a hexagonal stcruurte due to the alnge between hyoenrdgs 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 voapr meeculols stick to the six srhap edges and expand the snowflake outwards, bit by bit. A snowflake's dvlenpeoig shape denpdes on amhiteopsrc conditions, like humidity and tarueptrmee. As a snowflake falls, changes in weather cindotnios can affect how it gwros, 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 simailr, a stmmireyc snowflake can grow. Weather conditions affect snow on the ground, as well. wemrar ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes sctik to each other. Melted snow also plyas a critical role in another wintry activity, skiing. Completely dry snow is very difficult to ski on because there's too much ftoriicn between the jagged safnoelwks 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 sinkig. 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 binanchrg points in sfwanolke famroiton, and the dnieefcefrs in temperature and humidity, and while we wait for the anewsr, we can enjoy watching these tiny flctaras 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 _______ 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 ______ 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 ______ freezes into a solid, snowflakes form when water vapor turns straight into ice. But that still doesn't _______ 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 ________ 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 _________ from both hydrogens as they bond together, and the remaining four outer shell electrons from oxygen form two pairs. We call the _____ between these _____ 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 _____ molecule as a whole is electrically neutral, but ______ gets a ______ share of electrons, making it slightly negative and the hydrogens slightly positive. Due to its negative ______, 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 ________ bond, is formed. When water freezes, this bonding occurs on repeat, ultimately forming a hexagonal _________ due to the _____ between _________ 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 _____ _________ stick to the six _____ edges and expand the snowflake outwards, bit by bit. A snowflake's __________ shape _______ on ___________ conditions, like humidity and ___________. As a snowflake falls, changes in weather __________ can affect how it _____, 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 _______, a _________ snowflake can grow. Weather conditions affect snow on the ground, as well. ______ ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes _____ to each other. Melted snow also _____ a critical role in another wintry activity, skiing. Completely dry snow is very difficult to ski on because there's too much ________ between the jagged __________ 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 ______. 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 _________ points in _________ _________, and the ___________ in temperature and humidity, and while we wait for the ______, we can enjoy watching these tiny ________ falling from the sky.

Solution

grows
snowflake
sharp
hydrogens
formation
oxygen
friction
answer
developing
atoms
skiing
warmer
angle
structure
simply
molecule
fractals
differences
examine
snowflakes
branching
depends
water
temperature
similar
stick
charge
molecules
bonds
liquid
electrons
hydrogen
symmetric
conditions
plays
larger
vapor
atmospheric
explain

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

activity
affect
air
angle
answer
atmospheric
atom
atoms
attracted
bit
bond
bonding
bonds
branching
call
called
catch
charge
charged
charges
closely
clouds
compare
completely
conditions
covalent
creating
critical
cube
cubes
deeper
degrees
delve
depends
developing
differences
differentiate
difficult
dry
due
easier
edges
electrically
electron
electrons
enjoy
examine
expand
explain
falling
falls
find
form
formation
formed
forming
fractals
freezer
freezes
friction
frozen
gazing
glove
ground
grow
grows
happening
hard
helps
hexagonal
humidity
hydrogen
hydrogens
ice
identical
jagged
larger
layer
liquid
making
matter
melted
molecule
molecules
move
moves
mystery
negative
negatively
neutral
notice
occurs
outer
outwards
oxygen
pack
pairs
paths
physics
plays
points
positive
produce
protons
pushed
realize
remaining
repeat
repel
repulsion
retains
role
rub
scientists
seed
shape
shapes
share
shared
sharp
shell
sides
similar
simply
single
ski
skiing
skis
sky
slide
slightly
small
snow
snowflake
snowflakes
solid
solve
stay
stick
straight
stronger
structure
surface
symmetric
symmetrical
technically
temperature
temperatures
ten
tend
thin
tiny
true
turns
ultimately
unbonded
understand
vapor
wait
warm
warmer
watching
water
weak
weather
wetter
wintry