Chemistry Podcast

Sunday, 23 July 2017

What are the factors which favor formation of ionic bonds?

What are the factors which favour formation of Ionic Bonds?

These are the factors which favours formation of ionic bonds...
1. One of the atoms i.e. Metal atom must have low ionization energy, so that it can easily lose its electrons.
2. Other atoms i.e. Non-Metal atoms must have high electron affinity, so that it can hold the extra electrons.
3. One of the atoms i.e. Metal atom should be large in size.
4. Other atoms i.e. Non-Metal atoms should be small in size.
5. Lattice energy of the crystal should be high, means the electrostatic attraction between charged ions in the crystal should be high.
6. Anion and cation should have inert gas electronic configuration
7. The combining elements should differ by at least 1.9 in electronegativity.

Sunday, 16 July 2017

Chemistry Formulas for Nuclear Chemistry (Radioactivity)

Chemistry Formulas for Nuclear Chemistry (Radioactivity)

Empirical relationship between size of nucleus and its mass number is
            R = R0A1/3
            R = radius of nucleus,
            A = mass number,
            R0 = contestant = 1.4x10-13cm

Rate of Decayof radioactive substance

            K = decay constant,
            N = No. of atoms,
            t = time of decay,
            dN = small fraction of N,
            dt = small fraction of t

Value of Decay Constant

            N0 = No. of atoms originally present,
            N = No. of atoms present after time t

Half Life Time (t1/2)

            t1/2 = 0.693/K
            K = decay constant

Average Life Time (T)

            Average life time (T) =Sum of the lives of the nuclei/ Total number of nuclei
            T = 1/K 
            Average life time (T) = 1.44 x Half-life (T1/2)
            K = decay constant
            T = Average Life Time
            T1/2 = Half Life

Specific Activity

            Specific Activity = Rate of decay/m
                                      = KN/m
                                      = K x Avogadro Number/ Atomic Mass in gram
            N = Number of Radioactive nuclei that undergoes disintegration

Units of Radioactivity

            Standard unit of radioactivity is curie (c).
            1c = Activity of 1gram Ra226 = 3.7 x 1010dps
            dps = disintegrations per second
millicurie (mc) = 3.7 x 107dps
microcurie (µc) = 3.7 x 104dps
Other units of radioactivity are Rutherford (rd) and Becquerel (Bq).

Rutherford (rd)

1rd = 106dps

Becquerel (Bq)

            Becquerel (Bq) is the SI unit of radioactivity.
                        1Bq = 1 disintegrations per second
                        1 Bq = 1 dps

Radioactive Equilibrium

            A ----à B ----à C
            At steady state,
                        NA/NB = KB/KA = TA/TB
            KA = radioactivity constant for the process A---àB
            KB = radioactivity constant for the process B---àC
            TA = average life period of A
            TB = average life period of B
Radioactive Equilibrium in terms of half-life periods,
            NA/NB = (T1/2)A/ (T1/2)B


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