three rules are used to determine electron arrangement in an atom. section 3: electron configuration...
TRANSCRIPT
Three rules are used to determine electron arrangement in an atom.
Section 3: Electron Configuration
KWhat I Know
WWhat I Want to Find Out
LWhat I Learned
• 6(E) Express the arrangement of electrons in atoms through electron configurations and Lewis valence electron dot structures.
Electron ConfigurationCopyright © McGraw-Hill Education
Essential Questions
• How are the Pauli exclusion principle, the aufbau principle, and Hund’s rule used to write electron configurations?
• How do electron-dot structures represent an atom’s valence electrons?
Electron ConfigurationCopyright © McGraw-Hill Education
Review• electron
Electron ConfigurationCopyright © McGraw-Hill Education
Vocabulary
New• electron configuration• aufbau principle• Pauli exclusion principle• Hund’s rule• valence electron• electron-dot structure
Ground-State Electron Configuration
The arrangement of electrons in the atom is called the electron configuration. The aufbau principle states that each electron occupies the lowest energy orbital available.
Electron ConfigurationCopyright © McGraw-Hill Education
Ground-State Electron Configuration
The Pauli exclusion principle states that a maximum of two electrons can occupy a single orbital, but only if the electrons have opposite spins. Hund’s rule states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same energy level orbitals.
Electron ConfigurationCopyright © McGraw-Hill Education
Interactive Table – Electron Configurations and Orbital Diagrams
Concepts in Motion
FPOAdd link to concepts in motion interactive table from page 158 here.
Electron ConfigurationCopyright © McGraw-Hill Education
Interactive Table – Electron Configurations
Concepts in Motion
FPOAdd link to concepts in motion interactive table from page 159 here.
Electron ConfigurationCopyright © McGraw-Hill Education
Ground-State Electron Configuration
The aufbau diagram can be used to write correct ground-state electron configurations for all elements up to and including Vanadium, atomic number 23.
The electron configurations for certain transition metals, like chromium and copper, do not follow the aufbau diagram due to increased stability of half-filled and filled sets of s and d orbitals.
Electron ConfigurationCopyright © McGraw-Hill Education
Valence Electrons
Valence electrons are defined as electrons in the atom’s outermost orbitals—those associated with the atom’s highest principal energy level. Electron-dot structure consists of the element’s symbol representing the nucleus, surrounded by dots representing the element’s valence electrons.
Electron ConfigurationCopyright © McGraw-Hill Education
Interactive Table – Electron Configurations and Dot Structures
Concepts in Motion
FPOAdd link to concepts in motion interactive table from page 161 here.
Electron ConfigurationCopyright © McGraw-Hill Education
Electron ConfigurationCopyright © McGraw-Hill Education
Electron-Dot Structures
EVALUATE THE ANSWERThe correct symbol for tin (Sn) has been used, and the rules for drawing electron-dot structures have been correctly applied.
Use with Example Problem 3.
Problem Some toothpastes contain stannous fluoride, a compound of tin and fluorine. What is tin’s electron-dot structure?
ResponseANALYZE THE PROBLEMConsult the periodic table to determine the total number of electrons in a tin atom. Write out tin’s electron configuration, and determine its number of valence electrons. Then use the rules for electron-dot structures to draw the electron-dot structure for tin.
SOLVE FOR THE UNKNOWN
Tin has an atomic number of 50. Thus, a tin atom has 50 electrons.
• Write out tin’s electron configuration using noble-gas notation. The closest noble gas is Kr.
[Kr]5s24d105p2
The two 5s and the two 5p electrons (the electrons in the orbitals related to the
atom’s highest principal energy level) represent tin’s four valence electrons. Draw the four valence electrons around tin’s chemical symbol (Sn) to show tin’s electron-dot structure.
Electron ConfigurationCopyright © McGraw-Hill Education
Review
Essential Questions• How are the Pauli exclusion principle, the aufbau principle,
and Hund’s rule used to write electron configurations?• How do electron-dot structures represent an atom’s valence
electrons?
Vocabulary• electron
configuration• aufbau principle
• valence electron• electron-dot
structure
• Pauli exclusion principle
• Hund’s rule