CHAPTER 5 & 6 ELECTRONS IN ATOMS & THE PERIODIC TABLE

5.1 Models of the atom The Development of Atomic Models BIG PROBLEM: **Rutherford’s atomic model could not explain the chemical properties of elements.** BIG QUESTION: Why do elements produce different colors when heated? (a.k.a why do metals turn red when hot)

5.1 Models of the atom BIG SOLUTION: In 1913, Neils Bohr (Danish), stated that electrons could occupy fixed orbitals without giving off energy. Conclusions: -Electrons FARTHER from the nucleus have HIGHER energy, thus… -Electrons CLOSER to the nucleus have LOWER energy Chem Stud

5.1 Models of the atom **Like a staircase take energy to climb…electrons need energy to reach higher orbitals**

5.1 Models of the atom This theory was deduced from flame tests and gas tubes. Write down your observations of a flame test: Draw a picture of a gas tube:

5.1 Models of the atom This theory was deduced from flame tests and gas tubes. Write down your observations of a flame test: Draw a picture of a gas tube:

5.3 Physics and the Quantum Mechanical Model So… Why DO elements produce COLORS when HEATED? Let’s Brainstorm…take out your phones.

5.3 Physics and the Quantum Mechanical Model Bohr’s Answer **Since the amount of energy and electron has determines the distance it orbits from the nucleus, the electrons: ** 1.Take in energy (heat, electricity, or light) and move to higher energy levels (farther from the nucleus) 2.Release the extra energy as light and fall back to a lower energy level

5.3 Physics and the Quantum Mechanical Model We Say: “Electrons take in energy, jump up, fall back down, and release energy in the form of light.”

5.3 Physics and the Quantum Mechanical Model We Say: “Electrons take in energy, jump up, fall back down, and release energy in the form of light.”

5.3 Physics and the Quantum Mechanical Model We Say: “Electrons take in energy, jump up, fall back down, and release energy in the form of light.”

5.1 Continued…Models of the Atom Eventually, we learn the Bohr model is a lie. Bohr Modelreally isWave Mechanical Model (no distinct orbital boundary)

5.1 Continued…Models of the Atom This model does not show the path of electrons – Just the most PROBABLE location!

6.1 Organizing the Elements and Classifying the Elements Origin of the Periodic Table Dimitri Mendeleev – published the first real periodic table in Based upon chemical and physical properties -Listed elements in order of increasing atomic mass -Left spaces for undiscovered elements Chem Stud

6.1 Organizing the Elements and Classifying the Elements Predicting properties using other elements data:

6.1 Organizing the Elements and Classifying the Elements Predicting properties using other elements data: Example: Predict the density of Aluminum given: Density: Ga = 5.9 g/cm 3 & B = 2.3 g/cm 3 ** Find the Average!!!** Look…it doesn’t seem like much, but it’s what Mendeleev did.

6.1 Organizing the Elements and Classifying the Elements Modern Periodic Law: ** Properties are a periodic function of atomic number. **

6.1 Organizing the Elements and Classifying the Elements Periods: Groups: left to right on the periodic table up and down on the periodic table elements have the same # of energy levels elements have the same # valence electrons elements do not have similar properties elements have similar properties a.k.a rows, shells, and energy levels a.k.a families (columns)

6.1 Organizing the Elements and Classifying the Elements Metals, Metalloids, and Nonmetals

6.1 Organizing the Elements and Classifying the Elements Families:

Valance Electrons: Electrons that occupy the outmost shell of an atom This Guy 5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends

Valance Electrons: Electrons that occupy the outmost shell of an atom 5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends

Electronegativity: The ability of an atom to attract electrons. 5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends

Writing Orbital Notation: First things First, your PT is missing some things & 6.3Electron Arrangement in Atoms & Periodic Trends

Writing Orbital Notation:

Writing Electron Configuration: 5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends

Electron Notation in General: Electrons enter orbitals in a set pattern. For the most part, they follow the: -Aufbau Principle -Pauli Exclusion Principle -Hund’s Rule 5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends

Aufbau Principle: electrons must fill lower energy levels before entering higher levels. Pauli Exclusion Principle: electrons occupying the same orbital must have opposite spin. Hund’s Rule: (better known as the smelly guy on the bus rule) before any second electron can be placed in a sub level, all the orbitals of that sublevel must contain at least one electron

5.2 & 6.3Electron Arrangement in Atoms & Periodic Trends Practice…