How many atoms are in a bcc unit cell?
In a body-centered cubic (BCC) unit cell, there are two atoms. One atom is located at the center of the cube, and the other atom is positioned at each of the eight corners of the cube. Each corner atom is shared between eight adjacent unit cells, so it contributes only \((\frac {1}{8})\)th to the total count.
Thus, the total number of atoms in a BCC unit cell is:
1 (center atom) + \(\frac{1}{8}\) x 8 (corner atoms) = 2 atoms.
A cubic solid is made up of two elements $X$ and $Y$ Atoms of $X$ are present on every alternate corner and one at the enter of cube $Y$ is at $\frac{1}{3} td$ of the total faces The empirical formula of the compound is
List-I | List-II | ||
(A) | Hexagonal | (I) | ∝ ≠ β ≠ γ ≠ 90° |
(B) | Orthorhombic | (II) | ∝ = γ = 90°, β ≠ 90° |
(C) | Triclinic | (III) | ∝ = β = 90°, γ = 120° |
(D) | Monoclinic | (IV) | ∝ = β = γ = 90° |
All matter we encounter in everyday life consists of smallest units called atoms – the air we breath consists of a wildly careening crowd of little groups of atoms, my computer’s keyboard of a tangle of atom chains, the metal surface it rests on is a crystal lattice of atoms. All the variety of matter consists of less than hundred species of atoms (in other words: less than a hundred different chemical elements).
Every atom consists of an nucleus surrounded by a cloud of electrons. Nearly all of the atom’s mass is concentrated in its nucleus, while the structure of the electron cloud determines how the atom can bind to other atoms (in other words: its chemical properties). Every chemical element can be defined via a characteristic number of protons in its nucleus. Atoms that have lost some of their usual number of electrons are called ions. Atoms are extremely small (typical diameters are in the region of tenths of a billionth of a metre = 10-10 metres), and to describe their properties and behaviour, one has to resort to quantum theory.