chapters 2-6 Flashcards
(116 cards)
Why does Rutherford experiment use gold foil?
to scatter a-particles by hitting the atomic nucleus
atoms are electrically neutral:
protons = #electrons = atomic number
Element
any substance that can’t be broken down by chemical means
mass is the amount of substance
and it is the same on earth or moon
weight is different on earth than on moon
is the force gravity exerts on a substance
mass of proton =
mass of neutron = 1 dalton. 1 gram = 6.02 x 1023 daltons
a cation has more protons than electrons
Anion has more electrons than protons
Isotopes
are atoms of the same element with different numbers of neutrons: C12, C13, etc.
Radioactive isotopes
are unstable and decay at a constant rate measured as half-life
The chemical nature of an atom is dictated by
electrons in the outermost orbital (valence orbital)
electrons occupy discrete energy levels
K, L.. inside orbitals, each orbital with 2 electrons max
electronegativity is the affinity of an atom for electrons.
O = 3.5, N = 3.0, C = 2.5, H = 2.1
What does electronegativity make?
H2O is a polar molecule with oxygen being partially negative
Because of water’s polarity
hydrogen bonding is favored with O-acceptors and H-donors
Cohesion
when water molecules stick to each other at the surface
Adhesion
when water molecules stick to other polar molecules, such as glass
What does water cause hydrophobic molecules to do?
to aggregate or assume shapes like monolayers of micelles
Water is almost neutral: 1 molecule in 10
1 molecule in 10,000,000 ionizes
. strong acids dissociate completely in water
weak acids partially dissociate in water
. a buffer is a mixture of a weak acid + its salt that resists changes of pH
such as acetic acid + Na acetate
. the buffering comprises 1 pH unit above and 1 pH unit below the pKa of the acid
. primary functional groups are hydroxyl
carbonyl
. secondary functional groups are ester &thioester
ether & thioether
. structural isomers differ in structure of carbon skeleton