Chem final
formal charge
# of valence electrons - ( # dots + # lines), helps you find most favorable structure(best structure has fc=0 with neg fc on most e neg atom
Steps to drawing a Lewis diagram
1. Sum the valence electrons 2. Draw symbols with least eneg in middle (except H) and connect everything with single bonds 3. Make everything octet by adding dots 4. Count and compare to electrons in step 1 5. If you have too many e- make multiple bonds, if you have too few add extra to the central atom even if it exceeds octet, add ion bracket if you need to
How many Carbon atoms are contained in 2.8 g of C2H4
1.2 x 10^23(molar mass, avagadros, mol to mol)
What is the electron configuration of K +
1s2 2s2 2p6 3s2 3p6
What is a ground state e- configuration for an atom of Se
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4
1atm
760 torr and 760 mmhg
temporary dipole
A molecule where a temporary imbalance in the electron cloud causes a momentary imbalance of charge.
What is a pure substance
A single element(cannot seperate) or compound( seperble into simpler substances), not mixed with any other substance
Electronegativity
Ability of atom in a bond to attract e—, small atoms w large nuclei have, upper right, IE jumps from valence to core e-
expanded octet
An exception to the octet rule that permits atoms in the third row or lower on the periodic table to have more than eight electrons in a Lewis structure., easier when lone atom is big and multi plicated atom is small(in e neg)
Stronger bonds..
Are atoms closer in e- levels
What does a metallic bond look like
Array of positive metal ions surrounded by a sea of e-(delocalized)
What is the difference between an atom and an ion
Atoms have equal numbers of protons and electrons, resulting in no charge. Ions have gained or lost electrons, resulting in an overall charge.
Which elements have 6 e- to reach octet?
Be and B
Characteristics of covalent network solids
Between nonmetals, covalently bonded into 3d network, high mp, rigid and hard bc covalent bond angles are fixed, sheet itself held by cov bonds, sheet on top of sheet by ldfs, 1) crystalline= repeating pattern shape 2) amorphous= not repeating pattern shape
How do you find polar news in a bond btw two atoms
Biggest electronegativity- smallest eneg (.5 or less=non polar covalent, .5-2.0= polar covalent, 2.0+=ionic) larger dif= more polar
resonance structure
Bond can be anywhere but is needed
Physical traits of ionic bonds
Brittle(crystal lattice), crystalline, high mp( formula units in crystal lattice strongly attracted takes more e to overcome attractions), conduct e- in h2o(bc dissolve and dissociate into free flowing ions and free flowing ions conduct), cant conduct as a solid bc no free flowing ions, typically colorless or white crystals
The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of periodic properties, which of the following compounds can most likely be used as a fire resistant chemical? A. Bcl3 B. Ch4 C. Cbr4 D. Pbcl2
C
Which has the smallest radius and why Cl-, ar, k+, ca2+
CL minus, because its nuclear charge exerts the least attractive force on the electrons in the 3P sub level
Most ionic? CCL4, cucl2, cacl2, ncl3
CaCl2
Characteristics of mcc solids
Covalently bonded mcc attracted to each other through weak imfs, low mp, dont conduct bc Val e nit free held within cov bonds
What are the two types of network covalent solids
Crystalline- pattern, amorphous- no particular shape
A. RBCL has a high boiling point. Which of the following compounds is also likely to have a high boiling point, and why? b. NO, because its elements are in the same period of the periodic table C. CLF, because its elements are in the same group of the periodic table D. CL20, because its elements have similar electronegativities and it is a covalent cmpd
D
Which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference A. The first ionization energy of Al is greater than that of B because AL has a larger nuclear charge than B does B. The first ionization energy of F is greater than that of O because O has a higher electronegativity than F has C. The atomic radius of CA is larger than that of MG because the valence electrons in MG experience more shielding than the valence electrons in CA do D. The atomic radius of CL is smaller than that of S because CL has a larger nuclear charge than S does
D
Which of the following correctly identifies which has the highest first ionization energy, CL or Ar, and supplies the best justification A. CL because of its higher electronegativity B. CL because of it's higher electron affinity C. AR because if it's completely filled valence shell D. AR because of its higher effective nuclear charge
D
hydrogen bonding
Dipole dipole(strong) H atoms covalently bonded to to N,O, or F, can't have can experience or do
What is an alloy
Doesnt have constant composition, combining of 2 or more elements, 2 types
What must you do before determining electron domain and mcc geometry
Draw the Lewis diagram
Ionization energy
E required to remove VALENCE e-, IE directly proportional to fatt and magnitude inversely proportional to distance
Photoelectron spectroscopy
Each peak represents a sub shell, height =number of e- in that sub shell
What is a mixture
Either homogeneous( looks the same throughout) or heterogeneous (does not)
Bond energy
Energy required to separate atoms
Lattice energy
Energy required to seperate ions in ionic bond(directly proportional to fatt)
binding energy
Fatt or e that holds e- close to nucleus
Unshared pairs
Give polarity
magnitude
Greatness of size, strength, or importance(protons)
Metallic solid characteristics
Has sea of e- so great conductors, malleable, ductile(have charges on particles-dif btw them and interstitial alloy)
The Melting point of MGO is higher than that of NAF. Explanations for this observation include which of the following? I. MG 2+ is more positively charged than na+ II. 02- is more negatively charged than F- III. The O2- ion is smaller than the F - ion
I and II
What are the 2 types of alloys
Interstitial(form btw atoms w dif radii- smaller atoms fill interstitial space) and substitutional alloy(atoms of comparable radius but still not constant composition bc that's the dif btw an alloy and a compound)
When do you have ionic vs covalent character
Ionic when big difference in enegs, covalent when difference is small
Three types of bonds
Ionic( e- transferred from cation to anion to reach octet, metal & nonmetal, they stick), covalent(2 neutral atoms with positive nucleus and "negative middle" btw them, 2types= polar-shared e- and non polar= non shred e-, not permanent, return to parent atoms when bonds break, sharing e- in bond), metallic(e- move freely between nuclei-called delocalized e- or sea of e-, sea of e- allows metallic bonds to be malleable, ductile, and conductive)
What do mass spectrum graphs measure
Isotope abundance
What is the VSEPR theory?
It predicts the shapes of molecules based on the idea that electrons repel each other.
What is gravimetric analysis?
Lab where you pour thing and the precipitate dries
What is a network covalent solid
Large conglomeration of covalent mcc( crystals look ionic but connected w solid lines) 2 types
What is the electron geometry for two domains
Linear, 180 degrees(no mcc options)
Physical traits of covalent bonds
Low mp(bc no crystalline structure), dull, dont conduct e- bc no dissociated e-, poor heat conductors
Characteristics of ionic solids
Low vapor pressures, high melting points, high boiling points, brittle because sheets Slide Over each other and charges repel, conduct when melted
What is a mass spectrometer
Mass spectrometry involves firing molecules of varying weights through a circular tube and a magnetic field. The higher the molecule's weight, the less it is deflected by the magnetic field. The lower the molecule's weight, the more it is deflected by the magnetic field. We can use the differences in their deflection to separate molecules and identify them individually.
When drawing compound
Must look at atomic radius size and draw true to size(largest in bottom left)
Which of the following compounds contains both ionic and covalent bonds SO3, C2H5OH, MgF2, H2S, NH4Cl
NH4Cl
Gas
No fatt or imfs
Inter nuclear distance
Nucleus-nucleus, proportional to atomic radius and energy levels
Factors affecting pressure
Number of collisions, mass of particles, speed at which particles collide
bond order
Number of lines(bonds) divided by binding regions(everywhere there is a bond) ex: triple bond and single bond is 4/2
What math problems do you have to do for 1.1-1.4
Number of moles of precipitate produced in an expirement, mass percent of x in tablet, identifying xcl, limiting reactant problems, calculate theoretical and percent yields, filtration with filter paper problem
Density
P molar mass/ RT
How do you calc effective nuclear charge
P+ - core e-
Comparing 2 components
P1v1/T1n1= P2V2/T1n2
Ideal Gas Equation
PV=nRT (0.0821 latm/molk)
How do you do a mol fraction
Part interested in/ all of mol mixture
In a bond where do the partial charges go
Partial neg charge goes on atom w highest electronegativity
Kinetic mcc energy predicts
Pressure increases as temp of gas increases bc both gas mcc collide more frequently with the wall and the gas mcc collide more energetically with the wall
Excess reactant
Reactant that is left over
To determine the percentage of water in a hydrated salt a student heated 1.2346 g sample of the salt for 30 minutes when cool to room temperature the sample weighed 1.1857 g after the sample is heated for an additional 10 minutes and again cooled to room temperature sample weighed 1.1632 g which of the following should the student do next
Reheat the sample until its mass is constant
What's a chemical bond
Requires a transfer or sharing of electrons and attractions can exist without being bonded(mixtures not chemically bonded.
interstitial alloy characteristics
Rigid bc of interstitial atoms (not charged particles), retains sea of e- so conducts
How do you find number of valence electrons
S and p in the highest energy level( other electrons are core)
analogous compounds
Same groups will bond similarly
Physical trait of metallic bonds
Shiny, malleable(bends), ductile(stretches), conducts e- in both liquid and solid form, good heat conductors, high melting point, all caused by sea of electrons
What is electron domain with four domains
Tetrahedral(109.5), 3 bonding &1 nonbonding is trigonal pyramidal, 2 nonbonding&2 bonding is bent
The further an e- is from a nucleus
The easier it is to remove and the less Ionization Energy it takes
What's electron domain geometry
The five basic shapes with all domains bonding
London dispersion forces
The intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles. - increase with contact area(size of e- cloud based on molar mass) and polarizability(more e- in cloud)
In his atomic theory, Dalton proposed that all atoms of a given element are identical. Which of the following observations provides the best evidence that the proposal is incorrect
The mass spectrum of cu has a peak at 63 amu and another at 65 amu
In general when choosing between Lewis structures..
The preferred structure is always the Lewis structure where octet is satisfied without using multiple bonds, even if fc isn't ideal
Where do the electrons in a bond shift
Towards the atoms with the negative partial charge( highest eneg), dipole points toward most eneg atom
Electron domain with five domains
Trigonal bypyramidal(120 in triangle and 90 btw up and down and triangles), 4 bonding 1 nonbonding= seesaw, 3 bonding 2 nonbonding= t shaped, 2 bonding 3 nonbonding= linear
What is electron shape with three electron domains
Trigonal planar(120 degrees), bent(mcc with one nonbonding side)
IE highest where
Upper right(dist trumps magnitude)
What makes gases less ideal
Volume down, temp down, pressure up bc they create imfs bc they're moving slow
When do ionic compounds conduct electricity
When they have charged particles and the particles are free to move
ion-dipole forces
attractive forces between an ion and a polar molecule
Atomic and ionic radii
decrease as you move left to right & increase as you move down
gas to solid
deposition
dipole-dipole forces
forces of attraction between polar molecules - the greatest bc act in addition to ldfs
What is an electron domain
in the VSEPR model, a region about a central atom in which an electron pair (bonding or nonbonding) is concentrated
What is a binding pair vs a non bonding pair
line, dots that don't bond
6 electron domains
octahedral( 90), 5 bonding 1 non= square pyramidal, 4 bonding 2 non= square planar
What are the two types of matter
pure substances and mixtures
What's molecular geometry
resulting shape after accounting for unshared pairs, repulsion's taken into account
Graham's law of effusion
skinny manny gets through, fatty chuck gets stuck, r1/r2=square root m2/m1
What is kinetic energy proportional to?
temperature
What is a limiting reactant
the reactant that runs out first and limits the amount of product that can be made
What is electron affinity
the tendency of an atom to attract electrons, the more neg kJ/mol the more likely it is to absorb, absorbing lowers pe
