1. The Atom

2. How small is an atom?
Think of a penny…
A penny contains about 2 x 1022 atoms of copper and zinc
Aluminum has average sized atoms diameter of cm
Aluminum foil is 50,000 atoms thick!

3. What is an Atom Made of? Nucleus
small, positively charged center of an atom that consists of protons and neutrons
Contains most of atom’s mass
Diameter is 1/100,000 the diameter of the atom
Protons positive charged subatomic particle with an electrical charge of 1+
Neutrons neutrally charged subatomic particles that do not have an electrical charge
Electrons negatively charged subatomic particles with an electrical charge of 1- that are found in the electric cloud

4. Kroger
Coke

5. Atomic Mass Unit
Def. a unit of mass that describes the mass of an atom
SI unit for mass of particles
Carbon-12 is used by scientists to determine an atomic mass unit .
The amu is exactly 1/12 the mass of a carbon-12 atom.
Because carbon-12 has six protons and six neutrons in its nucleus, the mass of a proton and the mass of a neutron are each considered to be 1 amu.

6. How do atoms of different elements differ?
By the number of protons, neutrons, and electrons!
Atomic number= (Z) number of protons in the nucleus of a given atom
Q. What is the atomic number for …
Nitrogen 7
Lead
A. 82

7. Mass Number
Def. (A) total number of neutrons and protons in the nucleus of an atom
Electrons are not included bc their mass is so small that they have little effect on the atom’s mass