Quantum Model in Atoms: Exploring Electron Configurations

1. Chapter 5 Electrons in Atoms

2. Section 5-1 The Development of a New Atomic Model • Rutherford’s model was great, but it failed to explain one key thing: how ____________ and ____________ were not ____________ to one another in the nucleus.

3. Particle Description of Light • A ____________ is the minimum quantity of energy that can be lost or gained by an atom. • A photon is a particle of electromagnetic radiation having zero mass and carrying a ____________ of energy. Ephoton= hv

4. Analogy for Photoelectric Effect • Photoelectric effect is the emission of light (electrons) from a metal when energy (heat or x-ray) hits the metal. • There needs to be a certain amount of energy (quanta) that must hit the electron for it to give off light. • This is like a coin-operated soda machine: • You need exactly 1 quarter to get the soda • You cannot use nickels, dimes, or pennies to get the soda, it must be the quarter.

6. Hydrogen Atom Line-Emission Spectrum • When current (____________ ) is passed through a gas at low pressure, the potential energy of some of the gas atoms ____________ . • The lowest energy state of an atom is its ____________ ____________ . • A state in which an atom has a higher potential energy than it has in its ground state is an ________________________ .

7. Excited and Ground States

8. Excited and Ground States of Atoms • When an excited atom returns to its ground state, it gives off the ____________ it gained in the form of electromagnetic radiation (visible as ____________ ).

10. Line-Emission Spectrum of Light • Hydrogen’s line-emission spectrum suggested that the ____________ of a hydrogen atom exists only in very specific ____________ ____________ .

11. Bohr Model of the Hydrogen Atom • Bohr proposed a model of the hydrogen atom that linked the atom’s ____________ with ____________ . • The electron can circle the nucleus only in allowed paths, or ____________ . When the electron is in one of these ____________ , the atom has a definite, fixed amount of ____________ . • The electron, and therefore the hydrogen atom, is in its ____________ energy state when it is in the orbit ____________ to the ____________ . • The energy of the electron is ____________ when it is in ____________ that are ____________ from the nucleus. • Electrons must be on a specific path around the nucleus. • Electrons can move from higher or lower energy levels, thus ____________ or ____________ energy. It doesn’t gain or lose energy.

14. The Quantum Model of the Atom • Bohr’s model of Hydrogen contradicted common sense. • Why did hydrogen’s electron exist around the nucleus only in certain allowed orbits with definite energies? • Why couldn’t the electron exist in a limitless number of orbits with slightly different energies?

15. Quantum Theory • Electrons do not travel around the nucleus in neat orbits, as Bohr had postulated. Instead, they exist in certain ____________ called ____________ . • An ____________ is a three-dimensional region of space around the ____________ that indicates the probable location of an ____________ . • In order to completely describe ____________ , scientists use ____________ numbers.

17. Atomic Orbitals and Quantum Numbers • The ____________ ____________ ____________ has only two possible values: _____ and _____ • These values indicate the two fundamental spin states of an electron in an orbital. • A single orbital can hold a maximum to _____ ____________ , which must have ____________ spins.

18. Atomic Orbitals and Quantum Numbers

19. Chapter 5-2 Electron Configurations • Electron configuration is the ____________ of ____________ in an ____________ .

20. Rules Governing Electron Configuration • ____________ principle: an electron occupies the ____________ energy orbital that can receive it.

21. Rules Governing Electron Configuration • ____________ ____________ principle: an atomic orbital describes the _________ of at most _________ electrons of _________ spins ( ) • ____________’s ____________ : orbitals of ____________ energy are each occupied by one electron before any orbital is occupied by a second ____________ , and all electrons in singly occupied orbitals must have the __________ ___________.

22. Electron Configuration

24. Representing Electron Configurations • Orbital notation, electron-configuration notation, and noble gas configuration • Sample problem: The electron configuration of boron is 1s22s22p1. How many electrons are present in an atom of boron? What is the atomic number for boron? Write the orbital notation for boron. • You might see something like this on a quiz or test:

25. Practice • The electron configuration of nitrogen is 1s22s22p3. How many electrons are present in a nitrogen atom? What is the atomic number of nitrogen? What is the orbital notation for nitrogen? • The electron configuration of fluorine is 1s22s22p5. What is the atomic number of nitrogen? How many of its p orbitals are filled? How many unpaired electrons does a fluorine atom contain?

26. Practice • What is the ground state of an atom? • What is the excited state? • What is an orbital? • The spin quantum number describes what? • How many orientations can each different orbital (s, p, d, and f) have around the nucleus? • How many electrons (maximum) fit in each level? How many sublevels are in each level? How many orbitals are in each sublevel? (text pages 131-132)