The radius of a lead atom is 175 pm. How many lead atoms would have to be laid side by side to span a distance of 1.58 mm?

If the radius is 175 pm then the diameter is 350 pm.

350 pm/atom x # atoms = 1.58E9 pm
Solve for # atoms.

20

The radius of a strontium atom is 215 pm. How many strontium atoms would have to be laid side by side to span a distance of 2.56 mm?

To find out how many lead atoms would have to be laid side by side to span a distance of 1.58 mm, we need to calculate the number of atoms in a given distance.

First, let's convert the radius of a lead atom from picometers (pm) to meters (m).

1 pm = 1 x 10^-12 m

So, the radius of a lead atom (175 pm) can be expressed as:

175 pm * (1 x 10^-12 m/1 pm) = 175 x 10^-12 m

Next, let's convert the distance we want to span from millimeters (mm) to meters (m).

1 mm = 1 x 10^-3 m

So, the distance of 1.58 mm can be expressed as:

1.58 mm * (1 x 10^-3 m/1 mm) = 1.58 x 10^-3 m

Now, we need to determine how many lead atoms can fit in the given distance.

The lead atoms can be considered as spheres with the diameter equal to twice the radius:

Diameter of a lead atom = 2 * radius = 2 * 175 x 10^-12 m = 350 x 10^-12 m

To find the number of atoms, we divide the total distance by the diameter of a lead atom:

Number of lead atoms = Total distance / Diameter of a lead atom

Number of lead atoms = (1.58 x 10^-3 m) / (350 x 10^-12 m)

Simplifying the expression, we cancel out the meters:

Number of lead atoms = (1.58 x 10^-3) / (350 x 10^-12)

Number of lead atoms = 4.51 x 10^9

Therefore, approximately 4.51 billion lead atoms would have to be laid side by side to span a distance of 1.58 mm.