stuff Flashcards
Mendeleev
created the periodic table of elements
rutherford
discovered the nucleus in gold foil experiment
dalton
first dude to prove that all matter is made of atoms and that chemical reactions were simply rearrangements.
thomson
first proposed that atoms were made up of positive and negative charges
bohr
proposed that electrons in an atom don’t exist as a cloud of negative charges, but rather occupy specific “orbits” around the nucleus with specific energies associated with them. Electrons can only absorb from one “orbit” to another, so they have to be in shells
proton, electron, and neutron size
p = 1 AMU e = almost 0 n = slightly more than 1 AMU
atomic number
number of protons in the nucleus
atomic mass
average m ass of all isotopes of the element = the one with the decimal
mass number
atomic mass rounded to the nearest whole number OR protons plus neutrons
ion charge (combining capacity)
the charge on ions of the element
neutrons
atomic mass - atomic number
quantum of energy
the difference in energy between two energy levels
orbital
describes where electrons can be found in an atom
s-subshell
sphere-shaped contains 1 orbital can contain 2 electrons lowest energy subshell exists in every shell
p-subshell
peanut-shaped
contains 3 orbitals
can contain 6 electrons
exists only in the second shell and larger shells
d-subshell
“double peanut” shape
contains 5 orbitals
can contain 10 electrons
only exists in third shell and larger shells
is shifted by one energy level on the periodic table (like if you see it in the 4th row then it is in the third shell)
f-subshell
flower shape
contains 7 orbitals
can contain 14 electrons
exists only in the fourth shell and larger shells
is shifted by 2 energy levels on the periodic table (so if you see it in the sixth row, then it is in the fourth shell)
valence electrons
all electrons outside of the core and electrons in filled d and f subshells
laws of electrostatic forces
1) opposite charges attract
2) like charges repel
3) the greater the distance between the charges, the smaller the electrostatic force between them
4) the greater the charge on the particles, the greater the electrostatic force between them
atomic number and electrostatic forces
as you go from left to right across a period, the atomic number increases = the number of protons in the nucleus increases = the amount of positive charges on the nucleus increases
but the average distance from the nucleus to the electron shells remain the same
atomic radius and electrostatic forces
as you go from left to right across a period, the atomic radius decreases. if there’s a higher charge, it shrinks because of higher attraction. if there’s a lower charge, it expands a bit because of lower attraction
as you go from top to bottom within a group, the number of electron shells increases. therefore, the atomic radius increases because when there are more layers, its wider
ionization energy
the amount of energy required to remove an electron from a neutral atom form a positive ion (K + energy = K+)
it increases as you go from left to right. the further the right, the higher the charge, thus the higher the attraction, thus the more energy is needed to pull them apart
as you go from top to bottom within a group, the ionization energy decreases because the distance between the nucleus and the electrons increase, so the attraction goes down.
shielding effect
competition between attraction of nucleus and repelling of electrons
polar molecules dissolve in ___
non-polar molecules dissolve in ___
polar solutions
non-polar solutions
electronegativity
the tendency of an atom to attract the electrons of another atom
in general, as you go from left to right across a period, the electronegativity increases
in general, as you go from top to bottom within a group, the electronegativity decreases
ionic bonds
the difference in electronegativity is greater than 1.6
covalent bonds
the difference in electronegativity is less than 0.2
polar covalent bond
results when the difference in electronegativity is between 0.2 and 1.6. it is a partial separation of charge = dipole
anions
negatively charged ions (gained electrons)
cations
positively charged ions (lost electrons)
the greeks
early form of elements, earth water fire and air
water is (polar/non-polar) hexane is (polar/non-polar)
polar
non-polar
polar molecule
unequal dipoles do not cancel out
