Question

Which missing item would complete this alpha decay reaction? 257/100 Fm= ________+4/2He

Answer 1

The technique here is to balance the number of particles which is the numerator and the number of protons which is the denominator

 

Therefore

NUMERATOR:

257 – 4 = 253

 

DENOMINATOR:

100 – 2 = 98

 the number of protons of an ion is simply its atomic number therefore, from the periodic table

98 = Californium

 

The answer here is that we will add an Isotope of californium, 253/98 Cf

Answer 2

Answer: ₉₈²⁵³Cf

253 is a superscript to the left of the symbol, Cf, which represents the mass number, and 98 is a subscript to the left of the same symbol, which represents the atomic number.

Explanation:

1) The alpha decay equation shows that the isotope Fm - 257, whose nucleus has 100 protons and 157 neutrons, emitted an alpha particle (a nucleus with 2 protons and 2 neutrons).

2) Therefore:

i) the mass number decreased in 4, from 257 to 257 - 4 = 253.

2) the atomic number decreased in 2, from 100 to 100 - 2 = 98.

3) Hence the formed atom has atomic number 98, which is californium, Cf, and the isotope is californium - 253.

4) The item that completes the given alpha decay reaction is:

₉₈²⁵³ Cf.

5) The complete alfpha decay reaction is:

₁₀₀²⁵⁷ Fm → ₉₈²⁵³Cf + ₂⁴He

You can verify the mass balance:

257 = 253 + 4, and

100 = 98 + 2