Chem Flashcards
_____ describes the orientation of the orbital
magnetic quantum number
mass number
protons + neutrons
number of protons in an element
atomic number
an atom with the same number of protons but a different number of neutrons
isotope
positively charged ions (losses electrons)
cations
negatively charged ions (gains electrons)
anions
how to find the molecular mass
the sum of the avg atomic mass for each element
avogadros number
6.022 x 10^23
molar mass
of g / 1 mol
specific isotope of an element
nuclide
daltons three laws
law of conservation of mass
law of definite proportions
law of multiple proportions
mass cannot be created or destroyed in ordinary chemical and physical changes
law of conservation of mass
a chemical compound always contains the same elements in exactly the same proportions by weight or mass
law of definite proportions
when two elements combine to form two or more compounds, the mass of one element that combines with the given mass of the other is in the ratio of small whole numbers
law of multiple proportions
what did the cathode-ray tube experiment by JJ Thomas discover?
tiny negative charged particles
What experiment by Robert Mulikan discovered the charge of electrons?
oil drip experiment
what did the gold foil experiment by Rutherford, Geiger, and Marsden discover?
nucleus of an atom
what discovery did the experiment “a-particle at Be” by James Chadwick do?
the discovery of neutrons
most of the atoms mass and all its positive charge are contained in a small core called what
the nucleus
the volume of an atom is mostly what
empty space
what provides stability in the nucleus
neutrons
3 types of hydrogen isotopes
protium deuterium and tritium
when the frequency and the energy are low, the wavelength is what?
the wavelength is long
what happens when the energy of a photon increases?
the wavelength gets shorter
the distance between adjacent crest of a wave
wavelength
the more frequently a wavelength will pass a given point, the wavelength will be what
shorter
energy is released or absorbed in discrete packets of energy
plancks hypothesis
very tiny packet of radiant energy
photon
plancks constant
6.626 x 10^-34 Jxs
inversely proportional to wavelength
energy
group 1,2, and 13-18 on the periodic table are called
main group elements
group 3-12 on the periodic table are called
transition metals
group 1 are called
alkali metals (except H)
group 2 are called
alkaline metals
group 17 are called
halogens
group 18 is called
noble gases
period 6 ( elements 58-71) are called
lanthanides
period 7 ( elements 90-103) are called
actinides
d 10^-1
deci
c 10^-2
centi
m 10^-3
milli
u 10^-6
micro
n 10^-9
nano
p 10^-12
pico
What is the rule surrounding significant figures in scientific notation?
all digits before the multiplication symbol are significant
What is the exception to significant figure rules?
if a value is a whole number, ends in a zero, with no decimal then the ending zeros are NOT significant (ex: 96,500)
When do you apply significant figure rules?
end of calculations
subtraction/addition rule for significant figures
the number of decimal places in the final answer is equal to the number with he least amount of decimal places
multiplication/division rule for significant figures
the number of sig figs is equal to the LEAST amount of total sig figs in the problem; look at the entire number
When do you not consider sig figs?
when using exact/known conversion factors
Based on the data collected from Thomson’s cathode ray experiment, he suggested the:
plum pudding model
What did Thomson lack in proving his plum pudding model?
evidence
Fully disproved the plum pudding model by shooting a-particles at an ultra thin sheet of gold foil and measured the angles of scattering
Rutherford’s Gold Foil Experiment
The gold foil experiment determined that the gold atom has a:
positively charged center, orders of magnitude smaller than the total mass of an atom (most of the atom is empty space)
The gold foil experiment helped to shape and develop what model of the atom?
nuclear model of the atom
3 parts of nuclear theory
- most of the atom’s mass and all its positive charge are contained in a small core called a nucleus
- due to electros being spaced out within the cloud, most of the volume of an atom is just empty space
- there are as many negatively charged electrons outside the nucleus as there are positively charged particles within the nucleus. this atom is electrically neutral
Rutherford and Chadwick discovered the unaccounted mass of an atom was due to what?
neutrons
the average atomic mass is the:
weighted average of all isotopes in the sample (amu=unit)
Where can you find an element’s atomic mass on a periodic table?
below the element symbol
an atom that gains or loses an electron
ion
a positive charged ion means an atom
lost electrons
a negatively charged ion means an atom
gains electrons
In the very market 1900s German physicist Max Planck proposed that electromagnetic radiation is not:
continuous by its quantized
Planck’s hypothesis said energy is
released or absorbed in discrete packets of energy
Back the Planck formulated the idea of quantized energy, he had no experimental evidence to support its existence. However, Albert Einstein came along and supplied the evidence through his Nobel prize winning experiment the:
photo electric effect
What did Einstein observe?
many metals emit photo electrons when light shines upon them
E = hv
Energy = Planck’s constant x frequency
E = hc/lambda
Energy = planck’s constant x speed of light / wavelength
Energy is what relation to wavelength?
inversely proportional
What did Bohr’s model explain?
why hydrogen atoms lose and gain discrete quanta of energy (photon) and why hydrogen’s electron does not spiral into the nucleus
What are two general concepts with the Bohr orbits?
the greater the n value, the higher the energy; the energy difference between orbitals decreased with increasing values of n
when electrons move up they what energy? (1-4) (3-4)
absorb
when electrons go down they what energy? (2-1) (4-2)
emit
an atomic model in which electrons are treated as waves; also called the wave mechanical model of the atom
the quantum model of the atom
states that we cannot know both the position and speed of an electron at the same time
Heisenberg’s uncertainty principle
Study of physics at the atomic level where energy is quantized in discrete, rather than continuous, levels.
quantum mechanics
electrons do not travel around the nucleus in orbits, but instead they exist in regions of probability called
orbitals
Just like the bohr model, shells with a larger principal quantum number are:
farther from the nucleus and have higher energies
a positive whole number that indicates the main energy level/shell (n=1, 2, 3, 4,…)
principal quantum number (n)
What does it mean if electrons have the same n value
they are in the same shell
l = 0
s
l = 1
p
l = 2
d
l = 3
f
Orbitals with the constant value of n and l are in the:
same sub shell and have the same energy
electrons in orbitals behave like the Earth spinning on an axis. the electron can only exist in one of two possible spin states which creates what?
magnetic fields
An atomic orbital may describe at most two electrons, each with opposite spin direction
pauli exclusion principle
The chemical behavior of an atom is determined by the distribution of electrons in electron shells
electron distribution
the point at which the electron probability is zero
node
the arrangement of electrons in an atom
electron configuration
condensed electron configurations are useful because they elevate the electron configuration of the what?
core elements
core electrons are not involved in the chemistries of the elements, so they are of less interest. Instead, chemists are more interested in what?
valence electrons
electrons in the outermost shell
valence electrons
What are the two exceptions to Aufbau rule?
chromium (Cr) and Copper (Cu) and they translate down their groups (6 and 11); they don’t fill up their 4s orbital
electron configuration of chromium
[Ar] 4s^1 3d^5
electron configuration of copper
[Ar] 4s^1 3d^10
How do you write electron configurations for cations?
remove electrons with the highest energy level (n)
unpaired electrons, attracted to magnetic field
paramagnetic
all electrons are paired; not attracted to magnetic field
diamagnetic
generally, it increases from top to bottom in a group (energy levels increases) and decreases from left to right across a period (# of protons increases, higher nuclear attraction)
the size of atoms (atomic radii)
The amount of energy required to remove an electron from an atom
ionization energy
the amount of energy required to remove the first electron
first ionization energy (IE1)
in general, they increase from left to right across a period (more protons, greater Zeff) and decrease as you move down a group (larger atomic size, electrons aren’t pulled as close to the nucleus)
first ionization energies for main group elements
What is an exception #1 to first ionization energy?
between groups 2 and 13 elements in the 2 and 3 row there is a decrease because group 13 will lose a p electron when they ionize and group 2 will lose a p electron when they ionize
When do ionization energies drastically increase?
when you begin removing core electrons
in general, the larger the radius of the atom, the greater ability to
lose electrons
the measure of the ability of an atom to attract an electron within a chemical bond
electronegativity
the energy change that occurs when an electron is acquired by a neutral atom
electron affinity
