In, 1937 Lawrence, in operating his cyclotron, bombarded a molybdenum-96 foil with deuterium ions (2h), producing for the first time an element not found in nature. He was initially unaware that the radioactivity produced by the "bombarded foil" was not from molybdenum but from a new, artificial element. It was his cooperation with Italian-American physicist <span>Emilio Segrè </span>that allowed the new element to be discovered. The answer is Technetium: Tc
Answer:
Momentum is the measure of the motion of an object found by multiplying the objects mass and velocity.
Symbol: p
Units: kg x m/s
Explanation:
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The statement is true. The octet rule refers to the general rule of thumb wherein atoms of main-group elements tend to bond with other atoms in such a way that each atom possesses eight electrons (octet) in their valence shell. They tend to form the same electronic configuration as the noble gases. However, there are some exceptions to this rule. One of which is silane, SiH₄. A hydrogen atom only has 1 valence electron and needs another electron to complete its energy level. This is unlike other atoms, for example, carbon which has 4 valence electrons and needs to form 4 covalent bonds to fill its energy levels. Thus, 4 hydrogen atoms need only 4 more electrons. This is given by the silicon atom which has 4 valence electrons. Therefore, when a silicon atom is bonded to 4 hydrogen atoms, the resulting molecule, SiH₄, is a stable one.
Answer:
Wide melting point range - impure sample with multiple compounds
Experimental melting point is close to literature value - pure sample of a single compound
Experimental melting point is below literature value - impure sample with multiple compounds
Narrow melting point range - pure sample of a single compound
Explanation:
The melting point of substances are easily obtainable from literature such as the CRC Handbook of Physics and Chemistry.
A single pure substance is always observed to melt within a narrow temperature range. This melting temperature is always very close to the melting point recorded in literature for the pure compound.
However, an impure sample with multiple compounds will melt over a wide temperature range. We also have to recall that impurities lower the melting point of a pure substance. Hence, the experimental melting point of an impure sample with multiple compounds is always below the literature value.
It's simple.
the number of protons in an atom never changes. And also, the no of protons is its atomic number.if you look up the periodic table, you will find a number on the top - left corner of each of the boxes. This is the atomic number.No 2 same elements on the periodic table have the same atomic number. So, all you have to do is search for a box that has the number 13 on it.
and by the way ... the element which you're searching for is Aluminium