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Chemistry Chapter 4 Arrangement of Electrons in Atoms

Chemistry Chapter 4 Arrangement of Electrons in Atoms. electromagnetic radiation- a form of energy that exhibits wavelike behavior as it travel through space wavelength ( λ ) - the distance between corresponding points on adjacent waves

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Chemistry Chapter 4 Arrangement of Electrons in Atoms

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  1. Chemistry Chapter 4Arrangement of Electrons in Atoms • electromagnetic radiation- a form of energy that exhibits wavelike behavior as it travel through space • wavelength ( λ )- the distance between corresponding points on adjacent waves • frequency ( f ) the number of waves that pass through a specific point in a specific time • hertz ( Hz )- a frequency of one wave per second

  2. Speed of Electromagnetic Radiation • The speed ( c ) of all wavelengths of electromagnetic radiation = 3.0 x 108 m/s. c = fλ IF “c” is a constant, then wavelength varies inversely with the frequency of electromagnetic radiation.

  3. Photoelectric Effect • photoelectric effect- the emission of electrons from a metal when light shines on that metal • quantum- the minimum amount of energy that can be gained or lost by an atom • photon- a quantum of light energy • ground state- the lowest energy state of an atom • excited state- a higher energy state

  4. Spectra • line-emission spectrum- The specific colors (frequencies) of light emitted when an atom returns to the ground state from the excited state. • It can be seen when the light is separated by a prism and will give an element a specific spectrum. • continuous spectrum- the emission of a continuous range of frequencies of electromagnetic radiation

  5. Section 2The Quantum Model of the Atom • Heisenberg Uncertainty Principle- it is impossible to determine simultaneously both the position and the velocity of an electron • Quantum theory- describes mathematically the wave properties of electrons • orbital- a three-dimensional region around the nucleus that indicates the probable location of an electron • Each orbital can contain a maximum of 2 electrons.

  6. Atomic Orbitals and Quantum Numbers • quantum numbers- specify the properties of atomic orbitals and the properties of the electrons in the orbitals • principal quantum number- indicates the main energy level occupied by an electron • the number of electrons possible per energy level = 2 n2 where n = energy level • angular momentum quantum number- indicates the shape of an orbital • s, p, d, & f • magnetic quantum number- indicates the orientation of an orbital around the nucleus of an atom • spin quantum number- indicates the two fundamental states of spin of an electron

  7. Orbitals • There is a single “s” orbital per energy level for a maximum of 2 “s” electrons per level. • the energy level for “s” orbitals = the period number • There are 3 “p” orbitals per energy level for a maximum of 6 “p” electrons per level. • the energy level for “p” orbitals = the period number • There are 5 “d” orbitals per energy level for a maximum of 10 “d” electrons per level. • the energy level for “d” orbitals is the period number minus 1 • There are 7 “f” orbitals per energy level for a maximum of 14 “f” electrons per level. • the energy level for “f” orbitals is the period number minus 2

  8. Section 3Electron Configurations • electron configuration- the arrangement of electrons in an atom • Rules governing electron configuration: • Aufbau principle- an electron occupies the lowest energy orbital that can receive it • Pauli exclusion principle- no two electrons in the same atom can have the same four quantum numbers • Hund’s rule- orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron

  9. Electron Configuration Notation • ORBITAL NOTATION: See pg 112-113. • ELECTRON-CONFIGURATION NOTATION: See pg 113 [Ne] 3s23p4 Do Practice #1 & #2 on page 113.

  10. Elements & Electron Configurations • 1st period elements- see periodic table • 2nd period elements • 3rd period elements • noble-gas configuration- refers to an outer main energy level occupied by eight electrons ( ns2np6 in most cases) • 4th period elements • 5th period elements • Do Practice #1-4 on page 121.

  11. Elements & Electron Configurations • Elements of the 6th and 7th periods contain “f” orbitals. • Do Practice #1 & 2 on page 122. • Do Section Review #5 on page 122. • Do Chapter review #33, 36, & 38 on pages 125-126. • Review for Chapter 4 Test

  12. Chapter 4 Test-(40 questions) • Know the meaning of the formula c = fλ . • Know the meaning of hertz, wavelength, photon, photoelectric effect, ground state, excited state. • Know how EMR travels through space. • Know how a line spectrum is produced. • Know what must happen for an electron to move between the ground and excited states. • Understand the Bohr model of atoms. • Know the definition of electron cloud, the quantum numbers, orbital. • Know how to calculate number of electrons per energy level.

  13. Chapter 4 Test • Understand the differences in the energies of different orbital sublevels. • Know Aufbau principle, Hund’s rule, & Pauli exclusion principle. • Identify elements using their electron configuration notation. • Determine the electron configuration notation of elements. • Know the definition of a noble gas. • Write an electron configuration notation using an element’s orbital notation. • Identify an element using its orbital notation diagram.

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