I. Atomic Structure (Sections 1.1–1.3).
A. Introduction to atomic structure (Section 1.1).
1. An atom consists of a dense, positively charged nucleus
... [Show More] surrounded by negatively
charged electrons.
a. The nucleus is made up of positively charged protons and uncharged neutrons.
b. The nucleus contains most of the mass of the atom.
c. Electrons move about the nucleus at a distance of about 2 x 10–10 m (200 pm).
2. The atomic number (Z) gives the number of protons in the nucleus.
3. The mass number (A) gives the total number of protons and neutrons.
4. All atoms of a given element have the same value of Z.
a. Atoms of a given element can have different values of A.
b. Atoms of the same element with different values of A are called isotopes.
B. Orbitals (Section 1.2).
1. The distribution of electrons in an atom can be described by a wave equation.
a. The solution to a wave equation is an orbital, represented by Ψ.
b. Ψ
2 predicts the volume of space in which an electron is likely to be found.
2. There are four different kinds of orbitals (s, p, d, f).
a. The s orbitals are spherical.
b. The p orbitals are dumbbell-shaped.
c. Four of the five d orbitals are cloverleaf-shaped.
3. An atom's electrons are organized into electron shells.
a. The shells differ in the numbers and kinds of orbitals they contain.
b. Electrons in different orbitals have different energies.
c. Each orbital can hold up to a maximum of two electrons.
4. The two lowest-energy electrons are in the 1s orbital.
a. The 2s orbital is the next higher in energy.
b. The next three orbitals are 2px, 2py and 2pz, which have the same energy.
i. Each p orbital has a region of zero density, called a node.
c. The lobes of a p orbital have opposite algebraic signs.
C. Electron Configuration (Section 1.3).
1. The ground-state electron configuration of an atom is a listing of the orbitals
occupied by the electrons of the atom in the lowest energy configuration.
2. Rules for predicting the ground-state electron configuration of an atom:
a. Orbitals with the lowest energy levels are filled first.
i. The order of filling is 1s, 2s, 2p, 3s, 3p, 4s, 3d.
b. Only two electrons can occupy each orbital, and they must be of opposite spin.
c. If two or more orbitals have the same energy, one electron occupies each until
all are half-full (Hund's rule). Only then does a second electron occupy one of
the orbitals.
i. All of the electrons in half-filled shells have the same spin.
II. Chemical Bonding Theory (Sections 1.4–1.5).
A. Development of chemical bonding theory (Section 1.4).
1. Kekulé and Couper proposed that carbon has four "affinity units"; carbon is
tetravalent.
2. Kekulé suggested that carbon can form rings and chains. [Show Less]