Ernest Rutherford
J. J Thomson
Explanation:
<u>Ernest Rutherford</u>
In 1911, Ernest Rutherford, a New Zealand chemist performed the gold foil experiment where he gave the modelling of the atom a boost.
Experiment
In his experiment, he bombarded a thin gold foil with alpha particles generated from a radioactive source. He found that most of the alpha particles passed through the gold foil while a few of them were deflected back.
Discovery and reflection on the atomic theory
To account for his observation, Rutherford suggested an atomic model in which an atom has small positively charged center where nearly all the mass is concentrated.
<u>J. J Thomson</u>
Experiment
In 1897 J.J Thomson performed experiments using the gas discharge tube that led to the discovery of the electrons. He called them cathode rays because they originate from the cathode and exits at the anode.
Discovery and reflection on the atomic theory
From his experiment on the gas discharge tube, Thomson was able determine the properties of cathode rays some of which are:
- they move in a straight line
- they possess kinetic energy
- they attract positive charges and repels negative charges
Using his observation, he proposed the plum pudding model of the atom where it is made up of entirely electrons.
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Answer: condenstation.
Justification:
The polymerization by condensation is a well know chemical reaction in which two monomers ("small" molecules), each with (at least) two functional groups, combine and relase water as by-product. Actually, even if the by-product released is not water, yet the reaction is called condenstation, since the mechanism is basically the same.
An example of such reaction is the manufacturing of nylon 6,6, which is produced from adipic acid and 1,6-diamine hexane:
HOOC - [CH₂]₄ - COOH + nH₂N - [CH₂]₆ - NH₂ → - nylon - + nH₂O
I omitted the formula of nylon because it is large, and that is not the core of the question but the fact the kind of reaction: two molecules combine to form is a larger molecule, and water is released
Answer:
1) Ca: [Ar]4s²
2) Pm: [Xe]6s²4f⁵
Explanation:
1) Ca:
Its atomic number is 20. So it has 20 protons and 20 electrons.
Since it is in the row (period) 4 the noble gas before it is Ar, and the electron configuration is that of Argon whose atomic number is 18.
So, you have two more electrons (20 - 18 = 2) to distribute.
Those two electrons go the the orbital 4s.
Finally, the electron configuration is [Ar] 4s².
2) Pm
The atomic number of Pm is 61, so it has 61 protons and 61 electrons.
Pm is in the row (period) 6. So, the noble gas before Pm is Xe.
The atomic number of Xe is 54.
Therefore, you have to distribute 61 - 54 = 7 electrons on the orbitals 6s and 4f.
The resultant distribution for Pm is: [Xe]6s² 4f⁵.
Answer:
The formula for the anhydrous compound that was part of the mixture called natron that was used by the Egyptians is Na2(CO3)10(H2O).
They use this compound for medicine, cookery, agriculture, in glass-making and to dehydrate egyptian mummies.
Compound of sodium carbonate and sodium bicarbonate was the name of the resulting hydrate that formed.
I think it is not possible to make cd without plastic . because except plastic no other material is so durable for making cd.
