Name: Electrovalency
Uploaded: 2019-07-19
Duration: 1 min 51 s
Description: Do you know how chemical bonds are formed? They are formed in order to attain a stable electronic configuration. Let's watch the video to learn about the pro...

Question

You have learnt that the value of e/m for electron is

2000

times that of the proton or

H^{+}

. Calculate the charge to mass ratio for

{He}^{+}

and

{He}^{2 +}

in comparison to e/m of the electron. Mass of helium is four times that of hydrogen.

Accepted Answer

Mass of $e^{-} = 9 .1 \times 10^{- 28} g$ and the charge of $e^{-} = - 1 .6 \times 10^{- 19} C$ .

Mass of $H^{+} = 1 .67 \times 10^{- 24} g$ and the charge of $H^{+}$ = $1 .6 \times 10^{- 19} C$ .

Charge of ${He}^{2+} = 2 \times 1 .6 \times 10^{- 19} C$

Given that mass of helium is four times that of hydrogen.

Therefore:

$\frac{{e/m for e}^{-}}{e / {m for H}^{+} or proton} = \frac{\frac{1 .6 \times 10^{- 19} C}{9 .1 \times 10^{- 28} g}}{\frac{1 .6 \times 10^{- 19} C}{1 .67 \times 10^{- 24} g}}$ $≃ 2000$

In this equation, e is the magnitude of charge and m is the mass of the sub-atomic particle.

Charge to mass ratio of ${He}^{+}$ in comparison to the charge to mass ratio of $e^{-}$ :

$\frac{{e/m of He}^{+}}{e / {m for e}^{-}} = \frac{\frac{1 x 1 .6 \times 10^{- 19} C}{4 x 1 .67 \times 10^{- 24} g}}{\frac{1 .6 \times 10^{- 19} C}{9.1 \times 10^{- 28} g}} = 1.36 \times 10^{- 4}$

Similarly, charge to mass ratio of ${He}^{2 +}$ in comparison to the charge to mass ratio of $e^{-}$ :

$\frac{{e/m of He}^{2+}}{e / {m for e}^{-}} = \frac{\frac{2 x 1 .6 \times 10^{- 19} C}{4 x 1 .67 \times 10^{- 24} g}}{\frac{1 .6 \times 10^{- 19} C}{9.1 \times 10^{- 28} g}} = 2.72 \times 10^{- 4}$

Column A	Column B
(a)Atomic number	(i)shells in an atom
(b)Isotopes	(ii)positively charged particles having mass equal to that of a hydrogen atom
(c)Valence electrons	(iii)number of positive charge on the nucleus
(d)Protons	(iv)electrons present in outermost shell
(e)K, L, M	(v)a technique to know the age of dead bodies
(f)Carbon dating	(vi)atoms having same atomic number but different mass numbers

You have learnt that the value of e/m for electron is $2000$ times that of the proton or $H^{+}$ . Calculate the charge to mass ratio for ${He}^{+}$ and ${He}^{2 +}$ in comparison to e/m of the electron. Mass of helium is four times that of hydrogen.

Important Questions on Structure of Atom

Learn and Prepare for any exam you want !

You have learnt that the value of e/m for electron is 2000 times that of the proton or H+. Calculate the charge to mass ratio for He+ and He2+ in comparison to e/m of the electron. Mass of helium is four times that of hydrogen.

Important Questions on Structure of Atom

Learn and Prepare for any exam you want !

You have learnt that the value of e/m for electron is $2000$ times that of the proton or $H^{+}$ . Calculate the charge to mass ratio for ${He}^{+}$ and ${He}^{2 +}$ in comparison to e/m of the electron. Mass of helium is four times that of hydrogen.