PHYS 1010Q Lecture Notes - Lecture 12: Maserati Granturismo, Scanning Tunneling Microscope, Unified Atomic Mass Unit
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PHYS 1010Q
Lecture 12
Atoms, Molecules, Gauge Pressure, Macroscopic & Microscopic Properties
Atom
Atoms are the fundamental building blocks of matter. To date, we know of 118 distinct
types of atoms. These are the chemical elements, 98 of which occur naturally. The
image is from a scanning tunneling microscope showing 48 individual iron atoms on a
copper surface. Atoms are very small in size, about 1023 atoms are in a gram of water.
The mass of an atom is usually given in amu (atomic mass unit) where 1 amu =
1.66x10^-27 kg.
Molecules
Atoms combine to form molecules. Some molecules are small like H20, others like
proteins and DNA are much larger. The distance between atoms in a molecule is about
10^-10 m. The atoms in a molecule are not just mixed together, but are joined in a well-
defined way.
Example: Given that a carbon atom has a mass of 12 amu, how many carbon atoms are
there in a diamond with a mass of 1 g?
Carbon= 12 amu (1 amu)^-23 kg = 1.992 x 10^-20 kg
M T= N nm
1g=N(1.992 x 10^-23)g/atm
N=5.02 x 10 ^22 carbon atomic
Fauge Pressure
Note that when you use a tire gauge, the reading is the difference between the higher
pressure on the inside of the tire and lower atmospheric pressure on the outside, Pg = P
– Patm.
Example: If the pressure gauge reads 32 psi for the tires of your 2017 Maserati
GranTurismo, what is the actual (or absolute) gas pressure inside the tires?
P g=P T-P atm
P g+ P atm=P t
32lb/m²+ 14.7 lb/m² = 64.7 lb/m² = 467PSI
Macroscopic & Microscopic Properties
Pressure
Pressure is the force exerted on a surface divided by contact area. The SI unit of
pressure is the Pascal which is a Newton per square meter. Other units include: 1 atm =
101 kPa = 14.7 psi = 760 mmHg.
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Document Summary
Atoms, molecules, gauge pressure, macroscopic & microscopic properties. Atoms are the fundamental building blocks of matter. To date, we know of 118 distinct types of atoms. These are the chemical elements, 98 of which occur naturally. The image is from a scanning tunneling microscope showing 48 individual iron atoms on a copper surface. Atoms are very small in size, about 1023 atoms are in a gram of water. The mass of an atom is usually given in amu (atomic mass unit) where 1 amu = Some molecules are small like h20, others like proteins and dna are much larger. The distance between atoms in a molecule is about. 10^-10 m. the atoms in a molecule are not just mixed together, but are joined in a well- de ned way. Carbon= 12 amu (1 amu)^-23 kg = 1. 992 x 10^-20 kg.
