Transcript hapter 2
CHAPTER 2
CONCURRENT ENROLLMENT
CHEMISTRY
ATOMS
ELECTRONS
Thomson found a charge to mass ratio of an
electron to be -1.76 x 108 C/g
Millikan’s oil drop experiment determined the
electron mass to be 9.11 x 10-31 kg
RADIATION
Becquerel discovered radioactivity
Three type of radiation
Gamma (γ) rays are high-energy “light”
Beta (β) rays are high-speed electrons
Alpha (α) rays are a 2+ charged He nucleus
COMPONENTS
Rutherford’s gold foil experiment
Atoms have a nucleus
Atoms are made up mostly of space
Protons exist in the nucleus with a + charge
Electrons mass is 9.11 x 10-31 kg, the charge is Protons mass is 1.66 x 10-27 kg, the charge is +
Neutrons mass is 1.67 x 10-27 kg, there is no charge
AMU means 1.66053 x 10-27 kg, so a proton and neutron are 1
AMU each
Atoms are small
Diameters between 1 x 10-10m to 5 x 10-10m, Ǻ = 1 x 10-10 m
so it is 1A to 5A
Isotopes have the same number of protons but different number
of neutrons
COMPOUNDS AND ELEMENTS
Compounds are made up of elements and the
number of each element
H2O
Atomic weights are an average of all the
isotopes for that element
Atomic weight = (% isotope#1)(mass)+(% isotope#2)(mass)
100
MOLES
An amount of a substance, similar to dozen.
One dozen eggs would not weigh the same as one
dozen horses, the same is true in atoms
One mole of anything is 6.02 x 1023 particles of that
substance. This is known as Avogadro’s number
If you times magnesium atoms mass to this number,
you will get 24.3 g per one mole. This is the atomic
mass of magnesium.
CHEMICAL FORMULAS
All compounds have constant ratios. This
means that the number of elements in a
compound remain constant
One mole of water would then contain, two
moles of hydrogen and one mole of oxygen
One molecule of water would contain, two
atoms of hydrogen and one atom of oxygen
Because of this law you can find mass
percentage of any element in any given
compound