Test (Chapters up till 7) Flashcards
introduction chapter
Who was george stahl? What theory did he propose? How does it work
George Stahl proposed phlogiston theory. Phlogiston flowed out of burning material. Burning stop when air became saturated w/ phlogiston.
what did Joseph priestly discover? What did he name it?
Oxygen. Named it dephlogisticated air.
Who was Antoine Lavoisier?
Father of modern chemistry. Disproved phlogiston theory. Explained combustion and stated it supports life. Published first modern book: elementary treatise on chemistry.
What law did Joseph Proust create? What is it?
Law of constant composition (or definite proportion). a given compound always has exactly the same proportion of elements by mass.
What law did John dalton propose? What was it
Law of multiple proportion. If elements combine in different ratios, they are always whole numbers.
Name all 4 parts of daltons atomic theory?
- each element is made of atoms
- atoms of given elements are identical
- chemical compounds are formed when elements combine. A combine always has the same relative # of atoms
- Chemical Reactions are reorganizations of atoms
What else did John dalton do?
Constructed a table of masses. Many were wrong but it was an important step in creating the periodic table
Joseph Gay Lussac and Amadeo Avogadro- What did they do?
determined formulas for compounds, gay-lussac measured volume of gases that reacted with each other at constant temp and pressure. Avogadro’s hypothesis interpreted lussacs experiments and proposed that a tthe same temp and pressure, equal volumes of different gasses contain the same number of particles.
What are all of the diatomic molecules?
H2, N2, O2, F2, Cl2, Br2, I2
What did Berzelius do?
discovered 4 elements, created a symbol system for elements, determined atomic mass of 50 known elements, and performed over 2000 experiments in 10 years.
Who was JJ Thomson?
discovered electrons
what is electrons charge to mass ratio?
e/m= 1.76*10^8 (C/g) *coulombs per gram
Plum Pudding Model?
since atoms are electrically neutral, atoms must be positive. The diagram was a positive cloud with electrons scattered inside of them.
Gold foil experiment?
determined positive charge was central
Oil drop experiment
Robert Millikan performed it to measure charge of an electron. Used charge to mass ratio.
Mass of an electron?
9.10*10^-28 (g)
Who was Henri Becquerel? What did he do? Who was Marie Curie? What did she do?
Henri saw a rock leaving an image on a photographic plate in absence of light. Marie curie coined it radioactivity. She later identified other radioactive elements. Won nobel prize for chem.
What is radiation? What are the 3 types?
It is spontaneous emission of radiation. Gamma rays are high speed energy (light/photon), Beta particles are high speed electrons, and aplha particles are helium ions (w/ no e-).
What are isotopes?
Atoms w/ different numbers of neutrons. Identical chemical properties. In nature, most elements are mixtures of isotopes.
What is counting by weighing?
Weigh a small sample, calculate the mass per unit, then weigh a larger sample and find the number of units.
how many g in one amu?
1.66*10^-24 (g)
What does a mass spectrometer do?
most accurate machine for atomic weighing.
Know how to calculate avg atomic mass
Avogadros number?
6.022*10^23
Know stoichiometry
Know % mass composition
Know how to find molecular formula from empirical formula
Know how to detrmine an empirical formula from a given mass
obtain masses. Calculate mass by % of each element. Assume 100g of compound. Calculate moles of each element. Calculate rations.
What is the Bohr Model?
Proposed electrons move in orbits rather than rings
Energy Equation from Bohr’s Model?
E= -2,178*10^-18 [Z^2/N^2] where e is energy, z is nuclear charge (# of protons), and n is integer (energy level)
Know how to calculate change in energy of an e- changing energy level in an H atom
Subtract original energy from final energy using equation for energy. A positive value indicates the system has gained energy.
What is the equation for the wavelength of light that must be absorbed for a certain change in energy?
(hc)/(change in energy) where h is planks constant (6.62610^-34) and c is the speed of light (2.9979*10^8 m/s). CHANGE OF ENERGY MUST BE ABSOLUTE VALUE. If the system is losing energy, a photon is emitted. IF it is gaining, you say a photon was absorbed
What are the 3 characteristics of light?
wavelength, frequency, and speed.
long wavelength means what frequency and energy? Short wavelength means what frequency and energy?
low frequency and low energy. High frequency and high energy.
equation relating wavelength, speed, and frequency?
wavelength*frequency = speed of light
what is the SI unit for frequency?
1/s or a Hz
Was the bohrs model successful for all atoms?
No, only applied to H, other atoms did not work. He did manage to show quantization of energy however.
Who developed quantum mechanical model?
Werner Heisenberg, Louis de Broglie, and Erwin Schrodinger.
What was the approach of quantum mechanical model?
viewed e- as a standing wave. Only certain orbits are shaped for e- to shape.
What is an orbital?
it has a characteristic energy and shape. Wave function gives no detailed info about it
Schrodingers EQ?
HY = EY
Heisenberg uncertainty principle?
There is an uncertainty in simultaneously knowing both the position and momentum of an e- at a given time
Quantum numbers
Each orbital is described by a series of numbers that describes various properties. You have principle quantum number (n), angular momentum quantum # (l), Magnetic quantum #(m1), and electron spin number (m2).
All orbital shapes? How many e- can be held in each.
S, P, D, and F. 2, 6, 10, and 14. An orbital in each subshell holds 2.
Pauli Exclusion Principle?
In a given atom, no 2 electrons can have same set of 4 quantum numbers (principle, angular momentum, magnetic, and electron spin) AN ORBITAL CAN ONLY HOLD 2 E- AND EACH HAS OPPOSITE SPINS DUE TO THIS!!! Many atoms have 2e- with 3 numbers the same, just not spin
E- correlation problem
e- pathway cannot be known for atoms w/ more than one e-, so repulsion cannot be exactly calculated.
Aufbaus principle?
Lower energy levels are filled first (4s is filled before 3d)
Hunds rule?
Orbitals fill one at a time before pairing up
Lathanides and Actinides
Lathanides: elements in which the 4f orbitals are filled. Sometimes 1-2 e- occupy the 5d orbital before 4f, since they have similar energy levels
Actinides: elements in which the 5f orbitals are filled. Sometimes 1-2 e- occupy the 5d orbital before 4f, since they have similar energy levels.
What are the two electron configuration anomalies you have to know?
Cr and Cu (4s orbital is half filled)
what did mendeleev do? What did moseley do?
correctly predicted elements to be discovered. Showed organizing table by atomic # showed better correlations
Trend for ionization energy? why?
Decreases down a group (e- are further from nucleus). Increases down a period (because e- are being added and do not fully shield each other). Ionization energy also increases with each e- removed, and spikes whenever you start removing core e-
Equation for effective nuclear charge?
Zeff = Z =S where Z is number of protons and S is number of shielding e-
What anomalies do you have to know for ionization energy? Why does it happen?
decrease in Be to B, N->O. Orbitals begin to double in the P, causing e- repulsion.
What is Electron affinity? What does it mean? What is the trend?
the energy change associated w/ addition of an e- to a gaseous atom. The more negative the electron affinity, the greater the tendency for an atom to accept an e-. A very negative EA means it is an exothermic process (lower energy), and lower energy is always better. A positive EA means the anion is higher in energy than the separated atom and e-. Increases across a period, and decreases down a group (generally).
What are the anomalies for EA? What are the examples of stable and stable ions?
Fluorine is an anomaly for its group. It has a smaller EA than Cl , but the rest of the group follows the trend. This is due to the small 2p orbital.
N-> N- (unstable since e- repulsion in occupied orbital), C -> C- is stable, O -> O- is stable, and O- -> O2- is unstable, and reacts quickly to form oxide compounds
How is Atomic Radius obtained for different compounds? Trends?
Covalent atomic radius: obtained from half of the distance between nonmetal atoms
Metallic radii: half the distance between the metal atom in a solid metal crystal
Non-metallic radii: atoms that do not form diatomic molecules are measured by estimating from various compounds
Decreases down a period due to increased Zeff and less shielding e-, and increases down a group since energy levels are bigger
How does atomic radius change for ions?
A cation is smaller, and an anion is larger.
What are isoelectric ions? How does their size compare?
Same number of e-. For these ions, size decreases when proton count increases. O2->F->Na+>Mg2+>Al3+
What is photoelectron spectroscopy?
used to determine the energy of e- in an atom. High energy photons are directed at a sample and kinetic energy of released e- is measured.
Ionic bonds?
between metal and nonmetal
What is lattice energy? How can it be determined? Equation for it? Trend for lattice energy?
The energy required to separate a mole of ionic compound into gaseous ions. It can be derived theoretically or from a thermodynamic cycling reaction: the born Haber cycle. Eel = (KQ1Q2)/d^2. K = 8.99*10^9, Q1 and Q2 are the charges on the particles, and d is distance. It calculates attraction force in JOULES. Formation of a lattice is an exothermic process. Lattice energy increases as charge increases, or when radii decreases!!! Ex: NaCl has a larger intramolecular force than CsI due to smaller atomic radius. CaO has a higher lattice energy than KI due to larger chargers
What is electronegativity?
tendency for an atom to pull shared e- to itself
Trends for Electronegativity?
increases down a period, decreases down a group. Same as Ionization energy.
Most electronegative element? Least?
Fluorine. francium and Cesium.
what is a polar covalent bond? What causes it?
Where there are partial charges on the molecule due to one atom being more electronegative than the other.
Who developed a scale for electronegativity?
Linus Pauling
How to calculate difference in electronegativity? What determines if they are ionic, polar, or nonpolar?
Subtract larger value from less. If it is 2 or more, it is likely ionic. If it is between 0.4-1.9 it is likely polar. If it is less than 0.4 it is likely nonpolar.
Know how to draw lewis structures
Octet rule?
Metals and nonmetals tend to form the most stable molecules when they are surrounded by 8e-
Exceptions to octet rule?
Be (most stable w 4e-) and B (stable w 6e-). 3rd period and beyond can house more than 8
What are dipoles? What is dipole moment?
They have a positive center and a negative center. dipole moment: a property of a molecule whose charge distribution can be represented by a center of + charge and a center of - charge.
Why can some molecules have polar bonds, but no dipole moment?
The bonds are arranged in a way that cancels out charges. Polarity is also dependent on shape.
What three shapes can be polar but have no dipole moment?
linear (180), trigonal planar (120), and tetrahedral (109.5).
Types of calculations you have to know: stoichiometry, calculate empirical formula from chemical analysis, % mass composition, empirical to molecular formula
know polyatomic ions
