According to the U.S. mint the nickels currently in circulation weigh 5.000 grams and contain 25% Ni (the rest is copper).
25% of 5.000g = 1.250 grams of Ni in a nickel coin / molar mass of Ni 58.71 g/mol = 0.02129 moles of Ni times the number of particles for one mole 6.02x10^23 = 1.28x10^22 atoms of Ni in one coin.
All together:
(0.25 x 5.000g) / (58.71 g per mol) x (6.02x10^23 atoms per mol) = 1.28x10^22 atoms Ni per coin.
Count the number of atoms that are all the way inside the cell. Each of these counts as 1. Count the number of atoms that are on a face, but not a corner or edge of the cell. Each of these count as 1/2. Count the number of atoms that are on an edge, but not a corner of the cell. Each of these count as 1/4. Count the number of atoms that are on a corner of the cell. Each of these count as 1/8. The final formula is: inside + 1/2 face + 1/4 edge +1/8 corner = total atoms per cell.
The rutile unit cell has a tetragonal structure with titanium atoms at the corners and center of the cell, and oxygen atoms at the faces of the cell.
A FCC or Face Centered cubic unit cell has 4 atoms. It is calculated like this. There are 8 corners of the unit cell and each corner has one atom.But each atom is shared by 8 unit cells. So. total no. of atoms at corners= 1/8 *8=1 atom . Also, there are 6 faces which have one electron in the centre of it. Each such electron is shared between 2 unit cells. This gives the total no. of atoms at the centre of faces of unit cell=1/2 * 6 = 3 atoms. Adding the two, we get four atoms in an unit cell 1+3=4 atoms.
Your question, if I understand it correctly, asks to explain the reasoning behind the coordination number, or number of adjacent atoms, of an atom in a simple cubic structure versus an atom in a face centered cubic structure (FCC).Before we proceed, I would like to clarify one thing:A unit cell of a simple cubic crystal has 1 atom, while a unit cell of FCC crystal has 4 atoms. This may be a little counterintuitive at first, but consider how the atoms are shared. For the simple cubic structure, there are eight individual atoms - one at each corner of the cube. The unit cell, however, has to share each atom with the 8 other adjacent cells. Thus a unit cell gets 8 atoms only 1/8 of the time, hence 8*(1/8) = 1 atom per simple cubic unit cell. Similarly, FCC has the 1 atom from simple cubic, plus half of the 6 atoms on each of it's faces. Thus, FCC has 4 atoms per unit cell.On to the main question. In short, given a homogeneous, perfect crystal the coordination numbers of all the atoms are the same. All atoms are shared equal with their neighbors.For the simple cubic case this is easy to see. Like the simple gumdrop creations of second graders, you can start at any gumdrop to make the creation. Any corner is the same relative to its neighbors as any other corner. For FCC the same is true.
In a face-centered cubic (FCC) unit cell, atoms are located at the eight corners and at the center of each face of the cube. This arrangement allows for efficient packing of atoms and a high packing density.
Count the number of atoms that are all the way inside the cell. Each of these counts as 1. Count the number of atoms that are on a face, but not a corner or edge of the cell. Each of these count as 1/2. Count the number of atoms that are on an edge, but not a corner of the cell. Each of these count as 1/4. Count the number of atoms that are on a corner of the cell. Each of these count as 1/8. The final formula is: inside + 1/2 face + 1/4 edge +1/8 corner = total atoms per cell.
To calculate the number of atoms in a unit cell, you first determine the type of unit cell (simple cubic, body-centered cubic, or face-centered cubic) and the number of atoms contributed by each lattice point. Then, you multiply the number of lattice points within the unit cell by the number of atoms contributed per lattice point. For example, a simple cubic unit cell has one atom per lattice point, so the total number of atoms in a simple cubic unit cell would be 1 x 1 = 1 atom.
In a diamond unit cell, each carbon atom is located at the corners of the unit cell. Since there are eight corners in a unit cell, each shared by 8 adjacent unit cells, the contribution to the total number of carbon atoms is 1/8 of a carbon atom per unit cell. Therefore, there is 1 carbon atom per unit cell.
The rutile unit cell has a tetragonal structure with titanium atoms at the corners and center of the cell, and oxygen atoms at the faces of the cell.
There are four zinc blende atoms per unit cell.
In one formula unit of nickel hydroxide (Ni(OH)2), there are two oxygen atoms.
There are two atoms per unit cell in the Body-Centered Cubic (BCC) crystal structure.
There are 8 diamond cubic atoms present in a single unit cell.
A FCC or Face Centered cubic unit cell has 4 atoms. It is calculated like this. There are 8 corners of the unit cell and each corner has one atom.But each atom is shared by 8 unit cells. So. total no. of atoms at corners= 1/8 *8=1 atom . Also, there are 6 faces which have one electron in the centre of it. Each such electron is shared between 2 unit cells. This gives the total no. of atoms at the centre of faces of unit cell=1/2 * 6 = 3 atoms. Adding the two, we get four atoms in an unit cell 1+3=4 atoms.
The main difference between these unit cells lies in the positions of atoms within the cell. In a simple cubic unit cell, atoms are only present at the cell corners. In body-centered cubic, there is an additional atom at the center of the cell, and in face-centered cubic, there are atoms at the cell corners as well as at the center of each face.
The repeating group of atoms in a crystal is called a unit cell. This unit cell is the smallest repeating structure that can be used to build up the entire crystal lattice.
Your question, if I understand it correctly, asks to explain the reasoning behind the coordination number, or number of adjacent atoms, of an atom in a simple cubic structure versus an atom in a face centered cubic structure (FCC).Before we proceed, I would like to clarify one thing:A unit cell of a simple cubic crystal has 1 atom, while a unit cell of FCC crystal has 4 atoms. This may be a little counterintuitive at first, but consider how the atoms are shared. For the simple cubic structure, there are eight individual atoms - one at each corner of the cube. The unit cell, however, has to share each atom with the 8 other adjacent cells. Thus a unit cell gets 8 atoms only 1/8 of the time, hence 8*(1/8) = 1 atom per simple cubic unit cell. Similarly, FCC has the 1 atom from simple cubic, plus half of the 6 atoms on each of it's faces. Thus, FCC has 4 atoms per unit cell.On to the main question. In short, given a homogeneous, perfect crystal the coordination numbers of all the atoms are the same. All atoms are shared equal with their neighbors.For the simple cubic case this is easy to see. Like the simple gumdrop creations of second graders, you can start at any gumdrop to make the creation. Any corner is the same relative to its neighbors as any other corner. For FCC the same is true.