© 2003 Mark S. Davis Chapter 2 Atomic Structure. © 2003 Mark S. Davis Law of Conservation of Mass...

© 2003 Mark S. Davis

Chapter 2

Atomic Structure

© 2003 Mark S. Davis

Law of Conservation of Mass

• Mass can be neither created nor destroyed in chemical reactions.

• The total mass of the products is the same as the total mass of reactants.

© 2003 Mark S. Davis

Law of Constant Composition

• Water is water, no matter where you get it; H2O is H2O

• The elements in a compound are present in a fixed and exact proportion regardless of the source.

© 2003 Mark S. Davis

Percent Composition

• Percent by mass of an element in a compound.– I.e. water

© 2003 Mark S. Davis

Practice

• Determine the percent composition of.

© 2003 Mark S. Davis

Dalton’s Theory• All matter is composed of atoms.• The atoms of any one element are

identical.• Atoms of different elements have

different masses.• Compounds are atoms combined with

other atoms.• In reactions, atoms are exchanged to

form new compounds.

© 2003 Mark S. Davis

Atomic masses

• Relative.

• Based on carbon-12.

• Isotopes.

• Mass numbers on Table reflect abundance of isotopes.

© 2003 Mark S. Davis

Practice

• Suppose in one crate there were 4500. g of oranges weighing 150. g each. How many oranges are in the crate?

© 2003 Mark S. Davis

Atomic Number

• Tells you…

© 2003 Mark S. Davis

Structure

• Protons

• Neutron

• Electron

© 2003 Mark S. Davis

Calcium

• Atomic number =

• What is the charge?

© 2003 Mark S. Davis

Ions

• Gain or lose electrons– ONLY ELECTRONS!

© 2003 Mark S. Davis

Calcium Ion

• What is the charge

© 2003 Mark S. Davis

Isotopes

• Identified by mass number

• C-12, C-13

• Alternate notation– Mass number above (superscript)– Atomic number below (subscript)

© 2003 Mark S. Davis

Average Atomic Mass

• What is the average mass of element Q? The abundances are:

© 2003 Mark S. Davis

Periodic Table

• Label appropriately…

• Properties of elements

• Tables 2.2 and 2.3

• Explained by organization in atom

© 2003 Mark S. Davis

Electromagnetic Radiation

• Electromagnetic spectrum

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Emission Spectra

• See figure 2.10, p 51

• Fireworks

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Absorption Spectra

• Radiation absorbed by atoms

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Model of the Atom

• Niels Bohr

• Explains Hydrogen

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Quantum numbers

• Tell you how the electrons behave

© 2003 Mark S. Davis

Principal Quantum Number

• The first quantum number

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Azimuthal Quantum Number

• The second quantum number

• Tells you the 3-D region in which you find electrons (orbital)

• Symbolized by l

© 2003 Mark S. Davis

Magnetic Quantum Number

• The third number

• Tells you the orientation of the orbital in 3-D space

© 2003 Mark S. Davis

Spin Quantum Number

• Final quantum number

• Tells you in which direction the electron spins

• Electrons behave like little magnets (spin gives magnetism)

• Value of + or – ½ or…

© 2003 Mark S. Davis

Putting it all together

• Table 2.6 and 2.7

• Orbital arrangement on the periodic table

• Electron configuration

• Aufbau principal– “Building up’

© 2003 Mark S. Davis

Pauli Exclusion Principal

• No more than two electrons per orbital

© 2003 Mark S. Davis

Hund’s Rule

• Electrons (little magnets) repel each other if they have the same spin

© 2003 Mark S. Davis

Pictures of Orbitals

• A d orbital

© 2003 Mark S. Davis

© 2003 Mark S. Davis

© 2003 Mark S. Davis

© 2003 Mark S. Davis

© 2003 Mark S. Davis

Chapter 1

• States of matter

• Classification of substances– Mixtures– Pure substances, etc

• Methods of separation of mixtures

© 2003 Mark S. Davis

Chapter 1

• Measurement

• Units

• Conversions

• Significant figures, calculations

© 2003 Mark S. Davis

Chapter 1

• Density and calculations

• Temperature and conversions

• Specific heat and calculations

© 2003 Mark S. Davis

Chapter 2

• Dalton’s ideas

• Percent composition

• Interpretation of the table– Masses, atomic number, etc

• Isotopes and average weighted mass

© 2003 Mark S. Davis

Chapter 2

• Quantum numbers

• Orbitals

• How to put them together…