Electron ConfigurationElectrons (e-’s) and Orbitals

Be sure to keep up on your reading from your text and studying your notes (scientific method, sigfigs, sci.

notation, electron configs, models, etc.). A quiz may be right around the corner… Or not… Or yes… Hint hint.

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)1. Solid-Sphere Model (Plum Pudding Model)2. Planetary Model (Rutherford’s Model)3. Quantum Model (WHAT WE KNOW TODAY)

Atomic Models

Rutherford’s model proposed electrons orbit the atom◦ This proved J. J. Thompson’s “Plum Pudding Model”

was incorrect ◦ States electrons orbited the atom like moons to a

planet

Bohr’s model confines e-’s to energy levels◦ 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

Atomic Models

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

Quantum Model

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

Orbitals

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!!

Electron Configurations

“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 ________)

“Building up” ??

Energy Levels

Write out the electron configuration for an element with an atomic number of 20

Atomic # = # of protons = # of electrons

1s22s22p63s23p64s2

We can abbreviate this using the LAST noble gas

i.e. [Ar] 4s2

Electron Configurations

Write the electron configuration for an atom of an element whose atomic number is 8.

Write the electron configuration for an atoms of an element whose atomic number is 34.

Write out the electron configuration for Copper.

Practice with e- Configurations

Draw these out.

Electrons MUST fill the lower energy levels before moving to the next. Each level is increasing energy.

Electron Configs

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

Electrons and Light

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 6.0221367 x 1023 of anything ◦ This value is known as Avogadro’s Number

Counting Atoms (real chem)

Molar Mass ◦ 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

Molar Mass

Calculate the molar mass of NH3

Calculate the molar mass of H2SO4

Calculate the molar mass of NaCl

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

Practice

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

Homework