The Crux of the Matter

Chapters 5 and 6

Rutherford used the gold foil experiment to prove the existence of the nucleus of the atom is positively charged and most of the atom’s mass is in the nucleus. He also showed that the electrons surround the nucleus.

John Thomson discovered the electron and its mass but Milikan’s Experiment

proved that electrons all have the same charge

57 and 89 Color as a d

hydrogen

71 and 103 color as a f

The Dual Nature of Light

• Wave Theory• Huygens proposed that light acted like

a wave- a transverse wave• Electromagnetic radiation( both

magnetic and electric properties• Speed of light 3 x 108 m/s• Different color light corresponds to

different wavelengths and frequency• When an electron gets excited or gains

energy it will quickly lose it ( think speed of light) in the form of a wave

• ROYGBIV- corresponds to wave length and frequency

• C =v ; c= speed of light , v = frequency and = wavelength

• Particle Theory• Newton , Planck, and Einstein

proposed that light acted like a particle• Particle called a photon which is a

bundle of energy with no mass• Photon travels in a wave like• Energy of a quantum E=hv (h is

Planck’s constant 6.626 x 10 -34 J * s) and v represents frequency

• Thus light has a dual nature

The RulesThe Aufbau Principle- states that each electron occupies the lowest energy orbital available

The Pauli Exclusion Principle- states that a maximum of two electrons can occupy a single atomic orbital, but only if the electrons have opposite spin.

Hund’s Rule- states that single electrons with the same spin must occupy each equal energy –orbital before additional electrons with opposite spins can occupy the same orbitals.

The Heisenberg Uncertainty Principle- states that it is fundamentally impossible to know precisely both the velocity and position of particle at the same time

Metals

• Luster

• Solid at room temperature, except Mercury

• Good conductors of heat and electricity

• Malleable

• Ductility

• Most elements fall into this category

Semi-metals or Metalloids

• Have both physical and chemical properties

Nonmetals

• They can be gases or a brittle solid at room temperature- except Bromine which is a liquid

• Poor conductors of heat and electricity

Alkali metals, Group 1, 1 valence electronAlkaline earth elements, Group 2, 2 valence electronsGroup 13 - use only last digit, 3 valence electronsGroup 14 - 4, Group 15 - 5, Group 16 - 6, Group 17 - 7, Group 18 - 8

Oxidation Number- this number tells you how many electrons an element needs to gain or lose to become stable. If (+) oxidation number then lose electrons, if ( –) oxidation number then needs to gain electrons.

The noble gases are stable- theyhave their lastenergy levelfilled. All exceptHelium have eight Valence electrons- calledThe Octet Rule

Valence electrons are the electrons found in the outermost energy level- you can never have more than 8- these are the electrons involved in bonding

The Modern Periodic Table

• Alkali Metals- most reactive metals, rarely found in nature alone, usually found in a compound

• Alkaline Earth Metals-also highly reactive, thus found in compound form, also common in minerals

• Transition metals- D-block metals, can be found separately in nature

• Halogens- most reactive nonmetals, most are gases

• Noble Gases- the most stable elements in the table, can only react under laboratory conditions, all the elements want to achieve their configuration

Atomic radius (AR)-half the distance between the adjacent nuclei in a crystal of an element

Ionic radius (IR)- the radius of an ion

* Ionization energy (IE)-the energy required to remove an electron from a gaseous atom

* Electronegativity(E)- the ability of an

atom to attract electrons in a chemical bond

*Shielding

Effect-the more

electrons between the nucleus and the outer electrons the more shielding

*reactivity