The periodic trend of reactivity depends on whether the elements are metals or nonmetals. For metals, reactivity increases down a group and from right to left across a period. Nonmetals do the opposite. For nonmetals, reactivity increases up a group and from left to right across a period. Therefore, the rank is as follows:
Fluorine
Selenium
Neon
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Answer:
Explanation:
The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.
Symbol= e-
Mass= 9.10938356×10-31 Kg
It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.
He constructed the glass tube and create vacuum in it. He applied electric current between electrodes. He noticed that a ray of particles coming from cathode to wards positively charged anode. This ray was cathode ray.
Properties of cathode ray:
The ray is travel in straight line.
The cathode ray is independent of composition of cathode.
When electric field is applied cathode ray is deflected towards the positively charged plate.
Hence it was consist of negatively charged particles.
Answer:
.Electron affinity is -142 kJ<---------->O(g)+e−→O−(g)Process involves single electron addition
O−(g)+e−→O2−(g)<--------> Electron affinity is +710 kJ. .Process is endothermic
Cl(g)+e−→Cl−(g)=Electron affinity is -349 kJ. Process involves single electron addition
None of the of thee reactions ----------Electron affinity is +142 kJ.
Explanation:
Negative electron affinity values indicate that energy is given out when the atom accepts an electron. Halogens evolve a large amount of heat on forming halide ions.
Substantial amount of energy is absorbed when two electrons are added to O2- thus its electron affinity has a positive sign. Energy is evolved on adding only one electron to form O- is hence it has a negative value of electron affinity as shown.
