1. Electron Configuration
Electrons (e-’s) and Orbitals

2. Atomic Models
Several models were created to explain the properties observed by the atom.
The charges of the electrons
The charges of the protons
The size, locations, and arrangement
Originally, scientists believed (chronologically)
Solid-Sphere Model (Plum Pudding Model, J.J. Thomson)
Planetary Model (Neils Bohr’s Model)
Quantum Model (Schrödinger and Heisenberg)

3. Atomic Models Rutherford’s model proposed electrons orbit the atom
The atom’s mass is mostly in the nucleus
States electrons were in a “fixed orbit”
Bohr’s model confines e-’s to energy levels
Orbited like moons around a planet
States e-’s can only be certain distances from the nucleus
This distance depends on the energy the e- has
The further away, the higher energy level

4. Quantum Model
The present-day model of the atom, in which electrons are located in orbitals, is also known as the quantum model
States electrons within an energy level are located in orbitals, regions of high probability for finding a particular electrons.
Does not, however, explain how the electrons move about the nucleus to create these regions

5. Orbitals
According to the current model of the atom, electrons are found in orbitals
-regions around the nucleus that correspond to specific energy levels
Orbitals are sometimes called electron clouds because they do not have sharp boundaries
Tells where it is likely to find an electron

6. Electron Configurations
Pauli Exclusion Principle
The principle that states that two particles of a certain class cannot be in the exact same energy state
Electron Configuration
the arrangement of electrons in an atom
Aufbau Principle (German for “building up”)
States that electrons fill orbitals that have the lowest energy first!!

7. “Building up” ??
“Building up” refers to the filling of all lower energy “sites” before increasing up in energy
Moving outward away from the (+) nucleus requires more energy for the (-) electrons to maintain the further distance
We have 4 orbitals (spots) that e-’s can go into:
s-orbital (holds ________) d-orbital (holds ________)
p-orbital (holds ________) f-orbital (holds ________)

8. Energy Levels

9. Electrons and Light
If an electron is in a state of lowest possible energy it is in the Ground State
If an electron gains energy, it moves to an Excited State
An electron in an excited state will release a specific amount of energy as it “falls” back down to the ground state.
This energy is emitted as certain wavelengths of light

10. Counting Atoms (real chem)
Atomic Mass
The mass of an atoms expressed in atomic mass units (AMU)
The Mole!!
A mole is just a counting unit (a quantity) for really small things (like atoms)
It is x 1023 of anything
This value is known as Avogadro’s Number

11. Molar Mass Molar Mass 1 mole has 6.022x1023 atoms (particles)
The mass in grams of one mole of the element
Has the units of g/mol
1 mole has 6.022x1023 atoms (particles)
Avogadro’s Number allows us to CONVERT between moles and grams

12. Practice Calculate the molar mass of NH3
Calculate the molar mass of H2SO4
Calculate the molar mass of NaCl

13. Practice Convert 12.5 grams of LiOH to moles LiOH
Convert 0.58 moles of H2O to atoms of water
Convert 1.28 moles of cobalt(II)oxide to mass

14. Homework Counting Atoms and Electron Configuration Worksheet Work on:
e- config for Mn,
Fe, and Co
Convert:
1.85 mol Al  g
8.9 g O  mols