Close Packing of Spheres, Atoms or Ions

Question 1

define close packing

Answer 1

the most space efficient way of arranging spheres in a fixed volume

Question 2

what is hexagonal close packing

Answer 2

A-B-A-B
third layer directly above the first layer
coordination number of 12

Question 3

what is cubic close packed

Answer 3

A-B-C-A-B-C
the thirds layer is in the holes from the first two layers
coordination number of 12

Question 4

what is body centred cubic structures

Answer 4

not close packed
2 spheres per unit cell
coordinate number of 8
spheres are in contact along the body diagonal

Question 5

ccp metals

Answer 5

Cu, Ag, Au, Al, Ni, Pb

Question 6

hcp metals

Answer 6

Be, Mg, Zn, Cd, Ti, Zr

Question 7

bcc metals

Answer 7

Fe, Cr, Mo, W, Ta, Ba

Question 8

does atomic radii increase or decrease across the oeriod

Answer 8

decrease

Question 9

does atomic radii increase or decrease down a group

Answer 9

increase

Question 10

how does the radius of a central ion affect the coordinate number

Answer 10

the higher the radius the higher the coordinate number because more ions can fit around it