CHAPTER 2CHAPTER 2

CONCURRENT ENROLLMENT CONCURRENT ENROLLMENT CHEMISTRYCHEMISTRY

ATOMSATOMS ELECTRONSELECTRONS

Thomson found a charge to mass ratio of an Thomson found a charge to mass ratio of an electron to be -1.76 x 10electron to be -1.76 x 1088 C/g C/g

Millikan’s oil drop experiment determined the Millikan’s oil drop experiment determined the electron mass to be 9.11 x 10electron mass to be 9.11 x 10-31-31 kg kg

RADIATIONRADIATIONBecquerel discovered radioactivity Becquerel discovered radioactivity

Three type of radiationThree type of radiationGamma (Gamma (γγ) rays are high-energy “light”) rays are high-energy “light”Beta (Beta (ββ) rays are high-speed electrons) rays are high-speed electronsAlpha (Alpha (αα) rays are a 2+ charged He nucleus) rays are a 2+ charged He nucleus

COMPONENTSCOMPONENTS Rutherford’s gold foil experimentRutherford’s gold foil experiment

Atoms have a nucleusAtoms have a nucleus Atoms are made up mostly of spaceAtoms are made up mostly of space Protons exist in the nucleus with a + chargeProtons exist in the nucleus with a + charge

Electrons mass is 9.11 x 10Electrons mass is 9.11 x 10-31-31 kg, the charge is - kg, the charge is - Protons mass is 1.66 x 10Protons mass is 1.66 x 10-27 -27 kg, the charge is +kg, the charge is + Neutrons mass is 1.67 x 10Neutrons mass is 1.67 x 10-27-27 kg, there is no charge kg, there is no charge AMU means 1.66053 x 10AMU means 1.66053 x 10-27-27 kg, so a proton and neutron are 1 kg, so a proton and neutron are 1

AMU each AMU each Atoms are smallAtoms are small

Diameters between 1 x 10Diameters between 1 x 10-10-10m to 5 x 10m to 5 x 10-10-10m, m, ǺǺ = 1 x 10 = 1 x 10-10-10 m m so it is 1A to 5Aso it is 1A to 5A

Isotopes have the same number of protons but different number Isotopes have the same number of protons but different number of neutronsof neutrons

COMPOUNDS AND ELEMENTSCOMPOUNDS AND ELEMENTSCompounds are made up of elements and the Compounds are made up of elements and the

number of each elementnumber of each elementHH22OO

Atomic weights are an average of all the Atomic weights are an average of all the isotopes for that elementisotopes for that element

Atomic weight = Atomic weight = (% isotope#1)(mass)+(% isotope#2)(mass)(% isotope#1)(mass)+(% isotope#2)(mass)

100100

MOLESMOLES

An amount of a substance, similar to dozen.An amount of a substance, similar to dozen. One dozen eggs would not weigh the same as one One dozen eggs would not weigh the same as one

dozen horses, the same is true in atomsdozen horses, the same is true in atoms One mole of anything is 6.02 x 10One mole of anything is 6.02 x 102323 particles of that particles of that

substance. This is known as Avogadro’s numbersubstance. This is known as Avogadro’s number If you times magnesium atoms mass to this number, If you times magnesium atoms mass to this number,

you will get 24.3 g per one mole. This is the atomic you will get 24.3 g per one mole. This is the atomic mass of magnesium.mass of magnesium.

CHEMICAL FORMULASCHEMICAL FORMULASAll compounds have constant ratios. This All compounds have constant ratios. This

means that the number of elements in a means that the number of elements in a compound remain constantcompound remain constant

One mole of water would then contain, two One mole of water would then contain, two moles of hydrogen and one mole of oxygenmoles of hydrogen and one mole of oxygen

One molecule of water would contain, two One molecule of water would contain, two atoms of hydrogen and one atom of oxygenatoms of hydrogen and one atom of oxygen

Because of this law you can find mass Because of this law you can find mass percentage of any element in any given percentage of any element in any given compoundcompound