Cations are than the elements from which they form. (b) Anions are than the elements from which they form. Choose the correct response regarding unit cells in each statement. (c) cubic unit cells have identical particles on all corners, and in the center. (d) cubic unit cells have identical particles on all corners, and on all faces of the cube. (e) cubic unit cells have identical particles on all corners of the cube.

Question

Chemistry

Dayton Fischer

18 February, 00:48

Cations are than the elements from which they form. (b) Anions are than the elements from which they form. Choose the correct response regarding unit cells in each statement. (c) cubic unit cells have identical particles on all corners, and in the center. (d) cubic unit cells have identical particles on all corners, and on all faces of the cube. (e) cubic unit cells have identical particles on all corners of the cube.

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Answers (1)

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Ada Weber · Answer 1

a) Cations are smaller than the elements from which they form.

b) Anions are larger than the elements from which they form.

c) Body-centered cubic unit cells have identical particles on all corners, and in the center.

d) Face-centered cubic unit cells have identical particles on all corners, and on all faces of the cube.

e) Siimple cubic unit cells have identical particles on all corners of the cube.

Explanation:

1) The ionic radius is, like the atomic radius, the distance between the center of the nucleus of the atom and the stable electron furthest from it, but referring not to the atom, but to the ion. This increases in the table from right to left by periods and from top to bottom in groups.

In the case of cations, the absence of one or more electrons decreases the electric force of mutual repulsion between the remaining electrons, causing them to approach each other and to the positive nucleus of the atom from which an ionic radius is smaller than the atomic.

In the case of anions, the phenomenon is the opposite, the excess of negative electrical charge forces electrons to move away from each other to restore the balance of electrical forces, so that the ionic radius is larger than the atomic one.

2) A unit cell is the smallest repeating portion of a crystal lattice. The cubic unit cell has all angles equal to 90° and all lengths are equal.

Each cubic cell has 8 atoms in each corner of the cube, and that atom is shared with 8 neighboring cells. In the body centered cubic cell there is an additional atom in the center of the cube, and in the face centered cubic cell, an atom is shared between two unit cells along the face.