Chemistry

Chapter 4: Atomic Structure


I. Atom—basic unit of matter
A. Composed of 3 main subatomic particles
1. Protons


2. Neutrons


3. Electrons


B. Atomic Number (Z)—indicates number of protons in nucleus
1. Unique number for each element
2. Also shows number of electrons for neutral atoms


C. Mass Number (A)—number of nucleons in nucleus of an atom
1. Nuclide—atom where number of nucleons is known

a. May be designated as follows:


b. Also designated by:


2. Isotopes—atoms of same element that have different numbers of neutrons
a. Have same Z since number of protons identifies each element
b. A differs for each isoto...