chapter 13: electrons in atoms models of the atom electron arrangement in atoms
TRANSCRIPT
Chapter 13: Electrons in Atoms
• Models of the Atom• Electron Arrangement in Atoms
Chapter 13: Electrons in Atoms-- Models of the Atom --
The Evolution of Atomic Models• Dalton Model• Thomson Model• Rutherford Model• Bohr Model• Quantum Mechanical Model
Chapter 13: Electrons in Atoms-- Models of the Atom --
Dalton’s Model
• Solid indivisible mass• No concept of subatomic particles
Chapter 13: Electrons in Atoms-- Models of the Atom --
Thomson’s Model
• The “plum-pudding” model• Electrons stuck in positively charged material• Nothing about protons, neutrons, arrangements, or ion
formation
Chapter 13: Electrons in Atoms-- Models of the Atom --
Rutherford’s Model
• The first nuclear atom• Most of the mass is concentrated in the nucleus of the atom
Chapter 13: Electrons in Atoms-- Models of the Atom --
Bohr’s model
• Said electrons orbited nucleus in fixed definite paths• Each energy level has electrons that can “jump” (quantum
jump) to other energy levels based on specific amounts of energy (quanta)
Chapter 13: Electrons in Atoms-- Models of the Atom --
The Quantum Mechanical Model
• Mathematical solutions from Erwin Schrodinger’s model developed this
• Estimation of probability of where electrons are found in the “fuzzy cloud”
Chapter 13: Electrons in Atoms-- Models of the Atom --
The Quantum Mechanical Model• Designates energy levels of electrons by using principal
quantum numbers (n)– n = 1, 2, 3, 4, …– Average distance of the electron from the nucleus
increases with increasing values of n• Sublevels of arrangement (arrangements in space)
– Sublevel contains atomic orbitals (regions where electrons are most likely to be found)
– Denoted by the letters s, p, d, and f– Each orbital contains two electrons
Chapter 13: Electrons in Atoms-- Models of the Atom --
The Quantum Mechanical Model
Summary of Principal Energy Levels, Sublevels, and Atomic Orbitals
Principal Energy Level
Number of sublevels Type of sublevel
n = 1 1 1s (1 orbital)
n = 2 2 2s (1 orbital), 2p (3 orbitals)
n = 3 33s (1 orbital), 3p (3 orbitals),
3d (5 orbitals)
n = 4 44s (1 orbital), 4p (3 orbitals),4d (5 orbitals), 4f (7 orbitals)
Chapter 13: Electrons in Atoms-- Models of the Atom --
Atomic Orbitals
• In the p orbitals, the areas close to the nucleus that have very little probability of finding an electron are called nodes
s orbital
Chapter 13: Electrons in Atoms-- Models of the Atom --
Atomic Orbitals
• In the d orbitals, the areas close to the nucleus that have very little probability of finding an electron are called nodes
Chapter 13: Electrons in Atoms-- Models of the Atom --
Atomic Orbitals
Increasing Energy(increasing distance from
nucleus)
Energy Level (n) 1 2 3 4
Maximum # of electrons allowed
2 8 18 32
**The maximum number of electrons that can occupy a principle energy level is given by the formula 2n2