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Interference colors in the light reflected from a thin soap film ...

Evidently the **mass** of a deuterium **atom** is very nearly twice that of iH 1, while the
**mass** of ... These particles, which we now **know** are the nuclei of helium **atoms**,
are ... **Assume** it to be of copper, of **density** 8.8 gm/cm **3 Its** volume is 47ro3/**3** or
4.2 ... 30 (2) The force exerted by the **sodium** ion is + X qci~ 4-n-eo r 2 (**3**) The
force ...

For more information, see Interference colors in the light reflected from a thin soap film ...

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The Physics of Subatomic Particles

this indicates an **atomic diameter** of about 3.4 x 10''' **m** for an argon **atom**, ... that is
, **its atomic** number times the **average mass** of the proton and neutron. ... with
experimental **values**, and so it was **assumed** that this was the reaction ... The
accelerated electrons struck a nickel **crystal** at a normal to **its** ... **Avogadro's**
**constant**. ND.

For more information, see The Physics of Subatomic Particles

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**Unit** of **Density** - **Density Definition**, SI **unit**, Solved Examples

**Questions** 3: If you **find** a shiny rock, a carbon allotrope **with a volume** of 0.042
cm³ and a **mass** of 0.14 g, is it graphite or ...

For more information, see **Unit** of **Density** - **Density Definition**, SI **unit**, Solved Examples

A substance's density is defined as its mass per unit volume. The density symbol that is most commonly used is \rho

\text{ Density }=\frac{\text{ mass }}{\text{ volume }}

Given that

Sodium atom average density \rho = ?

Size(Diameter) of the sodium atom D = 2.5 A^{^0}

Avogadro's number NA = 6.023 * 10^{23} atoms

Atomic mass of sodium = 23 g = 23* 10^{-3} kg

Density of the sodium in its crystalline state \rho_c= 970 kg m^3

Step 1: Calculating the volume of the sodium atom

Radius of the Sodium atom r = \frac{D}{2} = \frac{2.5}{2} = 1.25 A^{^0}

r = 1.25 * 10^{-10} m \because \text{1 angstrom = } 10^{-10}

Volume sodium atom (sphere) = \frac{4}{3}\pi r^3

= \frac{4}{3}* 3.14 * (1.25 * 10^{-10})^3

= 8.1845 * 10^{-30} m^3

Step 2: Mass of the sodium atom using the Avogadro's law

1 mole of the sodium contains 6.023 * 10^{23} atoms has a mass 23* 10^{-3} kg

Mass of one sodium atom = ?

Mass of sodium atom = \frac{23* 10^{-3}}{6.023 * 10^{23}}

= 3.818 * 10^{-26} kg

Step 3: Determine the sodium atom average density

\text{ sodium atom average density } = \frac{\text{ Mass of sodium atom }}{\text{ Volume sodium atom }}

= \frac{3.818 * 10^{-26}}{ 8.1845 * 10^{-30}}

=4.67*10^3\ \ kg/m^3

Solid sodium atom average density \rho_s=4.67*10^{\ 3\ }\ \ kg/m^3

Given that, \rho_c= 970 kg m^3

Thus, in its crystalline form, the density of sodium and the density of solid sodium are not the same. Since atoms are packed tightly during the solid process. In the crystalline phase, therefore, the interatomic separation is very small.