What is the ratio of the number of atoms in the human body (~7 x 1027)
to the number of seconds since the Big Bang (13.7 billion years ago) ?
1) 6.2 x 10-11
2)1.62 x 1010
3) 3 x 103
4) 1
5) 5.4 x 105
Atomic description of matter
Atomic description of matter
AFM Measurements
40 µm
10 µm
3.0418
Gold Atoms in New AFM Measurements
nm
nm
nm
nm
nm
Park Systems Corporation Website: http://www.parkafm.com/AFM_guide/true_non_contact_mode_2.php
Idealized atomic description of matter
Idealized atomic description of matter
The mass of one atom is m (kg/atom).
The density of solid copper is ρ (kg/m3).
What is the volume occupied by one atom of copper in a solid?
1) m•ρ
2) m/ρ
3) ρ/m
4) m•(ρ3)
How does the diameter of one atom in a solid compare to the length of
an interatomic bond in our atomic model ?
1) The bond length is greater than the
atomic diameter
2) The bond length is less than the
atomic diameter
3) They are the same
Atomic model of copper wire
Atomic model of copper wire
Clicker Quiz
Given that for lead, its AW= 207.2, i.e. one mole has a mass of
207.2 grams, and the diameter of lead atom is d=3.0x10-8 cm,
what would our atomic model of matter predict is the density
of solid lead?
1) 12.7 g/cm3
2) 3.0 g/cm3
3) 7.3 g/cm3
4) 22 g/cm3
5) 1.2 g/cm3
Lead (Pb) is much softer than copper (Cu), and can be more easily deformed or pulled into a wire.
What difference between the two materials best explains this?
1) Pb and Cu atoms have different sizes.
2) Pb and Cu atoms have different masses
3) The stiffness of the interatomic bonds is different in Pb and Cu
Atomic model of copper wire
Atomic model of copper wire
nseries
n
Atomic model of copper wire
Interatomic Bond Stiffness in Copper
A copper wire is 2 meters long. The
wire has a square cross-section (that is,
it has four flat sides—it is not round).
Each side of the wire is 1 mm in width.
Making sure the wire is straight, you
hang a 10 kg mass on the end of the
wire. Careful measurement shows that
the wire is now 1.51 mm longer. From
these measurements, determine the
stiffness of one interatomic bond in
copper.
nseries
n
Clicker Quiz
You hang a 10 kg mass from a copper wire with a square
cross-section and the wire stretches by 8 mm. Now you hang
the same mass from a second copper wire with the same
length but with sides half as long.
How much does the second wire stretch?
1) 4 mm
2) 8 mm
3) 16mm
4) 24 mm
5) 32 mm