DINOSAURS!
Ever since I was a child, I have been obsessed. I loved learning and reading
about them, I loved watching movies about them, and especially loved Jurassic Park.
Though I preferred the idea of the non-carnivorous dinosaurs to the scary
carnivores.I also always felt
sorry for the more goat that got eaten by the T-rex. AND.... Jurassic Park 4 is coming out
in 2014 (supposedly).
Some
of my favorite childhood memories are the Dinofours books, the
Mark Teague and Jane Yolen Dinosaur books, the Land Before Time
movies, and I currently have a T-rex and a mini T-rex pillow pet!
In
Australia, there is an area called the Lark Quarry, which is home to
the only recorded dinosaur stampede. There are more than 3300 fossilized
footprints. A recent study done by researchers at the University of Queensland
has provided evidence that the animals were not actually running away from a
large predator(the previous story),
but instead were using the area as a water crossroads or type of
"superhighway."
They
seem nearly certain that the dinosaurs were smaller, ranging in size from a
chicken to an emu. By analyzing the tracks as they were, and then using a
three-dimensional computer modeling software, the researchers came to the
conclusion that the tracks were not actually from long-toed dinosaurs, but
instead from short-toed dinosaurs that dug there toes into a river body. One of
the scientists claimed that the dinosaurs were moving on the tippy-toes.
Cobalt has an atomic number of 27. It is a silver to gray transition
metal, but is never found by itself in nature. Rather, it is found in chemical
compounds. The name cobalt comes from the German word for evil spirit (goblin)
"kobald." Cobalt is
generally isolated as a bi-product of mining copper and nickel.
Cobalt
is known for giving a distinct blue color in glass,
ceramics, and glazes. It was from this fact that it was initially discovered. In
1735, Georg
Brandt, a Swedish chemist, was trying to prove that some element -
not bismuth, as was believed - caused the blue color mentioned above. An
interesting fact about this discovery is that it was the first new element
discovered since ancient times.
The
metal and its compounds are slightly toxic if it comes in contact with skin,
and more so if ingested. It is also highly magnetic, even up to very high
temperatures (Curie
Temperature). Cobalt is quite chemically active, and this is one of the
reasons that it is a component in many alloys. It has one stable isotope.
There
are numerous uses
for cobalt. One of these is the coloration of glass, ceramics, and glaze as
previously mentioned. When it comes to alloys, cobalt is used in numerous
compounds. Cobalt superalloys are particularly stable, and are occasionally
used in jet aircraft engines. These alloys are also used in many different
implants and joint replacements in the human body.
Cobalt
is also used in batteries and its radioactive isotope is used as a medical
radioactive tracer. Cobalt is also essential to all animal life. One of the
most common supplements that contains cobalt is vitamin B12.
Before
I begin, I need to explain the fact that myself and both of my older brothers
are all studying some form of Chemistry. So, for Christmas this year our family
board game was "Periodic Quest,"
which is a board game that involves moving along a Periodic Table, using die,
and cards (one for each element) to play different variations of the game -
some based on properties of the elements and others simply on atomic number.
We
finally all sat down to play the game a few nights ago and it was...enlightening
to say the least. My brother Stephen and I had forgotten that not everyone has
an extensive working knowledge of the Periodic Table. My parents had both taken
Chemistry courses before, in High School and College, but after years of doing
nothing with Chemistry they were very very rusty.
So,
to help my parents out, I am doing this post about the Periodic Table - its
history, uses, and organization.
The history
We
need to go back all the way to 1869 and a Russian chemistry professor named DmitrI Mendeleev. When
he was teaching, there were around 60 known elements (compared to the 118 of
today) and he began his table by ordering the elements by atomic weight - the
heaviness of an atom of an element compared to an atom of hydrogen. Mendeleev
was writing his own Chemistry text, and as he ordered the elements horizontally
he found that if he left gaps he found periodic (see what he did there)
vertical trends in the properties of some elements.
From http://www.aip.org/history/curie/periodic.htm
He
left these gaps and claimed that there were yet undiscovered elements that
would fill in the table and adhere to both the horizontal and vertical trends
identified. With this as a guide, some early Chemists (later
1800s) were able to discover elements that fit within the gaps that
Mendeleev had claimed would be filled. After these elements were discovered,
his table began to grow in importance.
The Uses
The
first
huge use of the Periodic Table is the atomic weight. This means the weight
of the nucleus of an atom of the element. This is generally around double of
the element's atomic number - i.e. Hydrogen is number 1, etc. The atomic number
is the number of protons in the nucleus of an atom of an element. The atomic
weight is generally double that of the atomic number because protons
(positively charged particles) and neutrons (neutrally charged particles) both
exist within the nucleus and are approximately the same weight. The electrons
(the negatively charged particles) exist outside of the nucleus in orbitals and
have a minimal weight.
The
horizontal trends of the Periodic Table or the "periods" reveal the
trends of atomic radius, ionization energy, electron affinity, and
electronegativity. As you move across a period, the atomic radius decreases, as
the additional protons and neutrons cause the electrons to be draw closer to
the nucleus. The other trends all act opposite to the atomic radius and
increase as you move across the period. Ionization energy is the amount of
energy required to remove an electron. The electron affinity is the amount of
energy released when an electron is added to an atom to make a negative ion
(from neutral to negative). The electronegativity is how much an atom wants
electrons.
The
vertical trends or "groups" (or "families") show some more
significant properties. It must be realized that elements in the same groups
have the same number of valence electrons or electrons in the outermost orbital
and this corresponds to the trends the exhibit. The most recognized families
are the Alkali metals (1), the Alkaline Earth metals (2), Halogens (17), and the
Nobel gases (18).Groups 3 to 10
show less strong relationships and thus don't get cool names.Some of the trends revealed by the
Periodic groups are: the atomic radius increases as you move down a family, a
decrease in ionization energy (since they are bigger and are held together less
tightly), and a decrease in electronegatitvity. A fun trend found inFamily 1 or the Alkali metals is that
they are exceedingly reactive with water (see below).
The
two rows set of by themselves at the bottom of the Table are arranged as such because
they do not quite fit the trends of the rest of the table. This is because they are
radioactive, and it makes the table more aesthetically pleasing.
I
think that is enough of an overview for today. Needless to say, we didn't
really end up playing the game. Instead, my brother and I got to spend the time
explaining the Periodic Table and its many uses to our parents. And you know
what - we had a blast.
