Question

need help with this. thanks

Please answer the following questions by replying: 1. Why is it that during alpha emission, the atomic number decreases by two, and the mass number decreases by four? In your answer you should consider what an alpha particle is. 2. In beta emission, the atom loses an electron, yet the atomic number increase by one and the mass number stays the same. How is this possible? It may help if you consider what happens to the number of neutrons and protons. 3. If an element is bombarded by a neutron and subsequently emits a gamma ray, then it follows that the mass number will increase by one. How is it then, that the atomic number remains unchanged?

Answer 1

Radio active elements emits particles and energy to form stable nucleus. alpha particles
has mass number[A =4} and atomic number [Z=2] . So when an element disintegrates by
alpha emission, the atomic number of new element formed will be 2 units lesser
and mass number will be 4 units lesser. Alpha particles are hellium nucleus.
For eg: when U-238 disintegrates by alpha emission [ 2-He-4] new element has
atomic number two unit lesser than parent atom
Also note that mass number/atomic number of species before decay will be equal
to total mass number/atomic number of products.
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Beta emission increases atomic number by one ,because beta particles are electrons.
Since nucleus doesnot contain electrons ,so neutrons present in nucleus split in to
electron and proton. Thus one more proton is added to the nucleus. This will increase
atomic number of product by one
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Neutron bombardment
Neutron has mass 1 unit and charge zero.SO when it hit a nucleus , mass number increase
by one and atom ic number remains the same.
mass number/atomic number of species before decay should be equal
to total mass number/atomic number of products.

4te -Particles are That Helium Nue leus when means 2 a Tadio active tet element emit will have the new element dparticley atomic number 1ass a unit lesser numbur mass 4 unit les sey 2.34 Th 4 238 2 90 42 Total of pooduct 2+ 90 92 ato mic num ber 92 Atomic umber Yeactant To tal mass number of product mass number of 23 8 4 t 234 238 Teactant 23Pa + 2.3 4 1 h B alecay To tal atomic number -1 91 Atomic numbar of Yeactant 90 17 number Total masS Mass number of 23 4 = 01234-234 heactant

bombard menl- Neutron 345 t + GGammayays 16 I6 To tal otomic number l6 Total atumic number 16 + 00 16 Total mass number 3 10tal mass number 34 t1 3S