chem test3

electrons and orbitals

-There can be two electrons in one orbital maximum. -The s sublevel has just one orbital, so can contain 2 electrons max. The p sublevel has 3 orbitals, so can contain 6 electrons max. The d sublevel has 5 orbitals, so can contain 10 electrons max. And the 4 sublevel has 7 orbitals, so can contain 14 electrons max.

Lewis Dot Structure

-find total valence electrons -put least electronegative in middle -hydrogen on outside always, only 2 to fill shell -complete octets -if not complete, use double/triple bonds to share and complete octet

endothermic reaction

-heat on left side (reactant) -system absorbs heat from surroundings -requires energy -bonds BREAK -reactants have lower energy than products -products less stable than reactants -reaction is moving towards instability -products simpler (broken down) -solids to gas

exothermic reaction

-heat on right side (product) -system releases heat into surroundings -energy released -bonds FORM -reactants have higher energy than products -products more stable than reactants -heat released -products more complex

electron configuration

-the arrangement of electrons in an atom -left is S block, middle is D block, right is P block, lowest is f block -should add up to # of protons, in neutral, p=e -use noble gas to shortcut -ground state vs excited vs ionized -practice

Dalton's Atomic Theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

# of unpaired 1s22s23p1 1s22s22p6 1s22s22p43s1 [Ar]4s23d54p1

1, 0, 3, 6

An example of a molecule that exceeds the octet rule is AsCl5 which has ____ electrons around the central arsenic.

10

Which of the following corresponds to an electron configuration of a carbon atom in an excited state?

1s22s22p13s1

electron, write ground state 1s22s22p43s1 [Ar]4s23d54p1

1s22s22p5 (Ar)4s23d6

A molecule that exceeds the octet rule must come from period ______ or below.

3

An atom of boron in a compound does not need to have 8 electrons around it. Instead, a Lewis structure for the compound of BF3 contains

3 single bonds

How many orbitals are in the 4d subshell (sublevel) of an atom?

5

Consider the molecule NH3, where N is the central atom. How many valence electrons (total) are in this molecule?

8

Indicate which of the following ions or atoms has the highest first ionization energy. IncorrectS2- IncorrectP3- Correct:Ca2+ IncorrectK+ IncorrectCl-

????

Bohr Model

A model resembling planets revolving around the sun in orbits, useful in visualizing the structure of atoms.

when can there be a resonance structure

A molecule can have resonance structures when it has a lone pair or a double bond on the atom next to a double bond.

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.

Which of the following species has the smallest size? a) S2- b) S c) S2+ d) Cs+ e) Sr2+ 7. Which of the following species has the largest ionization energy? a) S2- b) S c) S2+ d) Cs+ e) Sr2+ --------------------------------------------------------------------------------------------------------------

C C

electronegativity trend

EN decreases from top to bottom & EN increases from left to right

Endo or Exo? An ice cube melts on a picnic table on a warm summer day. Solid carbon dioxide sublimes into gaseous carbon dioxide. Natural gas (CH4) is burned in a furnace. A banana becomes more rigid after being placed in liquid nitrogen for a period of time.

Endo Endo Exo Exo

Which of the following compounds exhibit at least one bond angle that is approximately 120o? Select "true" if the molecule has a bond angle of approximately 120o. Otherwise, select "false". CCl4 NH3 TeO3 OF2 SO2 COS

F, F, T, F, T, F

True or False? In a chemical reaction, the potential energy of the system is contained within the movement of the molecules. Burning a match must be an endothermic process overall because friction was needed to ignite the match. Energy can be defined as whatever is required to oppose a natural tendency for a process to occur. Chemical processes are not always easily reversible.

False False True True

h-bonding

H bound to F, N, or O. strongest. polar. VERY electronegative

currently accepted model

Heinsenberg

Rank the following bonds from least ionic to most ionic. Rb-Cl K-Br Cs-F

K-Br < Rb-Cl < Cs-F

Which of the following compounds exhibit trigonal bipyramidal electron geometry? Select true if the molecule exhibits trigonal bipyramidal electron geometry. Otherwise, select false. IF5, KrCl2, PCl5, XeF4, TeF6, ICl3, SeCl4

KrCl2, PCl5, ICl3, SeCl4

periodic table trends

Moving L to R: atomic radius decreases, ionization energy increases, electronegativity increases. Moving TOP to BOTTOM: atomic radius increases, ionization energy decreases, electronegativity decreases

Rank the following bonds from least polar to most polar. As-F P-F N-F

N-F < P-F < As-F

All structures below have central atoms which would exceed the octet rule except for ______. BrF4 NF3 IF3 SF4 BrF3

NF3

What does an orbital give?

Orbitals give a probability map of where it is likely to find an electron in an atom; a region in an atom where there is a high probability of finding electrons

To remove one electron from Mg requires a certain amount of energy. Which of the following is the best statement concerning the amount of energy in removing a second electron from magnesium?

Removing the second electron requires more energy because the second electron is being taken from a positive ion.

Rutherford model of the atom

Rutherford concluded that the atom is mostly empty space. All the positive charge and almost all of the mass are concentrated in a small region called the nucleus. Rutherford could NOT explain an atom's stability.

difference between intra and intermolecular forces

The atoms in molecules are held together by intramolecular forces whereas the molecules within a solid or liquid are held together by intermolecular forces.

What is ionization energy? cations IE?

The energy required to remove an electron from an individual atom in the gas phase. cations have higher IE than neutral

As the polarity of a covalent compound increases, the solubility of the compound in water increases.

True

If an element (abbreviated X) has a ground state electron configuration of [Ne]3s23p4, then the formula of the compound that X forms with sodium is Na2X. The ground state electron configuration for the undiscovered element 118 is [Rn]7s25f146d107p6. The expected ground state electron configuration for Ir is [Xe]6s25d7. The electron configuration of 1s22s22p63s23p34s23d1 is an excited state electron configuration for Ar. The element with a ground state electron configuration of [Ar]4s23d104p5 has 7 valence electrons.

True True False True True

VESPR

Valence Shell Electron Pair Repulsion

I- electron configuration

[ Kr ] 5s 2 4d 10 5p 6

At electron configuration

[ Xe ] 6s 2 4f 14 5d 10 6p 5

Pb+2 electron configuration

[Xe] 6s24f145d10

localized electron model

a model that assumes that a molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of the bound atoms

LDF forces stronger w

atomic radius

octet rule

atoms in stable molecules typically are surrounded by eight electrons (either in bonds or as lone pairs)

dipole-dipole forces

attractions between oppositely charged regions of POLAR molecules. second strongest

Intermolecular forces are proportional to

boiling point, melting point, vapor pressure

nonpolar covalent bond

bonds with itself. equally shared. 2 nonmetals. less electronegativity.

how cans atom lose energy? when atoms are in an excited state, how can they release this energy? is the Bohr model accepted?

by emitting a photon, by emitting light, no

Electron movement

cannot be exactly determined

examples of exothermic reactions

combustion of fuels, corrosion of metals, reaction between acid and alkali, respiration, rain, ice melts when touched, propane burned, condensation, mixed chemicals give off heat

in excited state,

contains same # of electrons, dif orbitals. it's higher energy and further from nucleus. thus, shells are left unfilled when moved to next energy level

examples of endothermic reactions

denaturing enzyme, photosynthesis, decomp, cooking an egg, hand cold when ice touched, ice cream melts, sublimation

What is the strongest type of intermolecular force in each of the following compounds? PF3, CH3CH2NH2, XeF4, H2, ICl5

dipole, Hbond, LDF, LDF, dipole

polar covalent bond

electrons are shared unequally. more electronegative. side positive and one side negative. 2 nonmetals.

Hund's Rule

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

In general, the rows on the periodic table correspond to ______________ and the columns numbered 1A, 2A, ... 8A correspond to ______________ .

energy level of valence electrons, # of valence electrons

4f14 3d10

first f level first d level * practice unpaired electron diagrams!

intermolecular forces

forces of attraction between molecules, weaker; london disperal, dipole dipole, H-bonding

since molecules want to stay together,

formation of bonds requires less energy than breaking down

as atomic size increases, LDF

get stronger

rutherford- bohr- heisenberg- thompson- dalton-

gold foil, atom is empty space with electron orbiting in fixed path negatively charged electrons orbit a small + nucleus, plants and sun theory of quantum mechanisms, can't predict path plum pudding model, atom consists of - and + charges, atom neutral, charged particles all matter has atoms, indestructible, atoms of element identical

anions have _____ atomic radius than neutral cations have _____ atomic radius

greater, smaller

electronegativity electron affinity

how much an atom wants to hog an electron how much they want electrons noble gases are not electronegative

As the polarity of a covalent compound increases, the solubility of the compound in water

increases

which is stronger, intermolecular or intramolecular?

intramolecular forces stronger

strongest intermolecular force? intra?

ionic, polar covalent, non-polar covalent ionic-> ion/ion, LDF, highest boil/melt polar w/ h bonds -> h-bonding, second best polar covalent -> dipole dipole non polar-> LDF

2 effective pairs

linear, 180

VEC

look at highest energy level, include everything in that energy level.

Ionic compounds are ____ soluble than covalent If closer together, then If further apart, then

more less polar more polar and ionic if metal and nonmetal

dissolves more with attracted to

more polarity most electronegative

Which of the following elements could be X? (There may be more than one possible answer. Choose "yes" or "no" for each element.) Ar, Ne, P, Xe, As, N

no no yes no yes no

possible to satisfy octet rule? AsF5 BeH2 NF3 KrCl2 PCl3 PCl5

no, no, yes, no, yes, no

ideal gas molecules are best considered to be

non-polar

bond type H2 H2O AlF3

nonpolar covalent polar covalent ionic

Which of the following compounds are polar? Select "polar" or "nonpolar" for each compound. PBr5, SeF6, SeF4, BrF5, ClF3, XeF4, XeCl2

nonpolar, nonpolar, polar, polar, polar, nonpolar, nonpolar

ion-ion interactions

occur between ionic compounds (metals and nonmetals). very strong. highest boiling/melting

6 effective pairs

octahedral 90 180 square pyramidal 90 180 square planar 90 180

resonance structure

one of the two or more equally valid electron dot structures of a molecule or polyatomic ion

quantized energy

only certain energy levels are allowed

polar or nonpolar? NH3 SO3 SF2 TeO2 CF4 COS

polar non polar polar non polar

polar vs nonpolar

polar: bent/asymmetrical, partial charges, stronger bonds nonpolar: symmetrical in all directions, no charge, weaker bonds

polar and nonpolar

polar= must have polar bonds. partially -, partially +. electrons shared unequally. most H (H-F, H-Br). THEN, consider if non symmetrical- bent. pyramidal. T-shape. seesaw. diatomic. all outside atoms not the same. nonpolar= diatomic. hydrocarbons. share equally. complete symmetrical- linear. trigonal planar. square planar. tetrahedral. trigonal bipyramidal. outside atoms are all the same.

How many electrons can be contained in all of the orbitals with a principle energy level of 3?

principle energy 1= 2 principle energy 2= 8 principle energy 3= 18 principle energy 4= 32

London dispersion forces

results from the constant motion of electrons and the creation of instantaneous dipoles. Only intermolecular for nonpolar and noble gases. weakest. more electrons, stronger.

Which of the following molecular shapes cannot have a trigonal bipyramid electron pair geometry? Select the following molecular structures which can arise from an octahedral electron pair arrangement. What is the molecular shape of IF5? What bond angles are present in structures with octahedral geometry?

square planar square pyramid, square planar square pyramid 180, 90

Pauli Exclusion Principle (According to the Pauli Exclusion Principle, what is the maximum number of electrons that can exist in a given orbital?)

states that a maximum of two electrons can occupy a single atomic orbital but only if the electrons have opposite spins

Aufbau Principle

states that each electron occupies the lowest energy orbital available

more electrons if ionization energy low

stronger attraction least energy to remove electrons

system vs surroundings

system: what is being studied/changed, focus in chemical reaction surroundings: everything which is around the system and may cause a change

4 effective pairs

tetrahedral, 109.5 trigonal pyramidal 107 bent 104.5

ionic bond

the attraction between oppositely charged ions. metals and nonmetals. largest electronegativity. no sharing. transfer of electrons. most polar. a noble gas configuration is formed for each element or ion.

first ionization energy

the energy required to remove the first electron from an atom. with subsequent energies, takes more energy. (3rd highest) similar to removing electrons

The greater the electronegativity difference,

the more ionic/polar the bond is

What is electronegativity?

the relative ability of an atom in a molecule to attract shared electrons to itself

if there's no central atom

then bond defines polarity

What is the shape of each molecule below? Select the correct answer. Answers can be used more than once. PBr5, KrCl4, TeF6, ClF3, BrF5, XeF2, TeCl4

trigonal bipyramidal square planar octahedral T-shape square pyramidal linear see-saw

5 effective pairs

trigonal bipyramidal, 90 120 180 see saw 90 120 180 T-shape 90 180 linear 120 180

shape of each CO2 SO3 NH3 SO2 OCl2 CH4

trigonal planar trigonal pyramidal bent bent tetrahedral

3 effective pairs

trigonal planar, 120 bent, 120

memorize VESPR shape, bond angles, and geometry

use chart to supplement http://chem.illinois.edu/chemdoodleweb/table.html http://butane.chem.illinois.edu/gadams4/chem101video/VSEPR/five.html

finding valence electrons

use group number! The Group 1 atoms have 1 valence electron. The Group 2 atoms have 2 valence electrons. The Group 3 atoms have 3 valence electrons. The Group 4 atoms have 4 valence electrons. The Group 5 atoms have 5 valence electrons. The Group 6 atoms have 6 valence electrons. The Group 7 atoms have 7 valence electrons. The Group 8 atoms have 8 valence electrons.

how to find unpaired electrons

write ground state configuration, then draw orbital diagram

Which of the following compounds/ions exhibit resonance? Select "yes" or "no" for each compound. SO2, CNS-, SeO2, TeO3, N3-, AsI3

yes, yes, yes, yes, yes, no