Midterm 2 Part A Flashcards by Sarah Boratynec

Chemical bonding: ___ that keeps atoms _____

Force

Together

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3 types of chemical bonds

Ionic

Covalent

Metallic

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Ionic Bonding: between a ___ and a ____. Involves a _____ of electrons

Metal

Nonmetal

Transfer

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Ionic bonding: forms ____ structures , forms compounds that are ___,___,and brittle

Extended

Hard

Rigid

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Ionic bonding: forms compounds that are poor _____ of heat and electricity in the ___ state

Conductors

Solid

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Ionic bonding: forms good electrical conductors in the ___ or ____ phases

Molten

Aqueous

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Ionic bonding: cation and anion are held together by attractive ______ forces given by Coulomb’s law

Electrostatic

E = (q1•q2)/d^2

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What is lattice energy

Energy that is released when gaseous ions bond to form the ionic solid

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What is lattic energy proportional to

And why is this important

The electrostatic force (E)

When looking at the trend for melting points of compounds we look at the size of the ions, and see the distance between them.

Larger distance= less lattice energy, meaning lower melting point

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Lattice energy helps determine the _____ of the bond

Strength

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If triangle H= (-770)J

What can we tell from this using the def of lattice energy

We need (-770)J to BREAK the ionic bond

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Higher melting point requires _____(less/more) energy

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What two things affect the melting point of a compound and why

Charges and distance between the atoms

These are the three variables on Coloumb’s law

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Steps for determining melting point trends

1) look at charges
-elements in compounds with GREATER numerical charge have HIGHER melting point

2)if two compounds have elements of the same charge: look at atomic mass of elements in each compound

-greater atomic mass=larger distance between nucli= smaller LE=lower melting point

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Covalent bonding: between a nonmetal and _____. Involves the sharing of _____.

Nonmetal

Electrons

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Covalent bonding: forms compounds with _______structure as well as extended ______

Molecular

Structures

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Covalent bonding: molecular compounds are typically gases or ____ with low melting or ____ points, whereas compounds with extended structures are ____ and rigid ____ with _____ melting points

Liquids

Boiling

Hard

Solids

High

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What are the two types of covalent bonds and give an example of each

Pure covalent bonds (H2, O2, Cl2)

Polar covalent bonds (HF)

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Pure covalent bonds have ____ sharing of electrons because of the SAME ___ of the bonded atoms

Equal

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Why do polar covalent bonds have an unequal sharing of electrons,

and which atom will draw electrons more strongly

Because the atoms have a difference in electro negativity

The atom with the HIGHER electronegativity will draw electrons more strongly

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How can bond polarity be determined and what is the formula for this

Determined by calculating
triangle(EN)

triangle(EN)=| (En positive) - (En negative) |

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Explain the difference between electron affinity and electronegativity

Electron affinity- referring to the ability of an ISOLATED atom in the GAS state to add an electron

Electronegativity- ability of an atom in a BOND to DRAW electron density

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Metallic bonding: between a metal and a ___. Has an _____ structure of atoms in “sea” of ______ electrons

Metal

Extended

Delocalized

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Metallic bonding: what does the sea of electrons do

Acts as a glue to keep the cations together

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Metallic bonding: Metals are malleable and ____. They are good conductors of heat and _____. They have moderately _____ melting and boiling points.

Ductile Electricity High

What is a stable electron configuration

Valence electrons are distributed so that each atom has 8 electrons, 2 for hydrogen

Steps for drawing lewis structure for covalent bonds

1) determine the total # of ve 2) use pairs to join all atoms 3) distribute remaining electrons 4) if compound has a (-) or (+) charge MUST PUT SQUARE BRACKETS AROUND AND INDICATE CHARGE

Exceptions to the octet rule and why this happens (What is this called)

Elements in period 3 and beyond can have 10 or 12 ve Because they can use their d orbitals in bonding (Expanded octet)

Incomplete octets: what does this mean and what elements are they

Elements may have LESS that 8 electrons Beryllium, Boron, and aluminum

Odd electron species: what is it and how to deal with it

There could be one unpaired electron This electron must be placed with the LEAST electronegative atom of the molecule

Formal charge: the difference between the # of ____ ___ in the free atom and the # of electrons _____ to the atom

Valence electrons Assigned

Formal charge formula and what must you do to calculate this

FC on an atom= ve-(e in lone pairs)- (1/2)(e in covalent bonds/pairs) Need to draw the Lewis structure to calculate formal charge on any element in the compound

All formal charges MUST __up to the overall ___ of the molecule

Add Charge

Low formal charges are ___, FC of ___ is the most stable

Preferred 0

(+) formal charges are preferred on the ____ electronegative atom, and (-) FC’s are preferred on the ____ electronegative atom

Less More

What is a resonant structure

Molecules that have MORE than 1 plausible Lewis structure. The true structure is then a resonance hybrid of all the contributing structures. Bonding electron density can therefore be delocalized over more than two atoms

What symbol represents a resonant structure

<—->

How to show a resonant structure

Insert picture of 03

Single bond has a bond order of ____ Double bond has a bond order of ___

1 2

In resonant structures all bonds are equivalent in ____ and _____

Length Strength

Lower bond order= ___ and ____ bond Higher bond order=___ and ____ bond

Weaker, longer Stronger, shorter

What is the prediction of molecular shape based on

The EXTENT of REPULSION between two electron pairs

Lewis structures: electron pairs are arranged around the central atom to ____ repulsion

Minimize

Molecular shape: AX2 # of electron pairs around central atom? Shape? Bond Angles?

2 Linear 2 bonding pairs

In the form AXE what do A, X, E represent?

A= central atom X= terminal atom E= lone pair

Molecular shape: AX3 # of electron pairs around central atom? Shape? Bond Angles?

3 Trigonal planar 120 degrees bond angle

Molecular shape: AX2E # of electron pairs around central atom? Shape? Bond Angles?

3 Bent, angular, v shape Less than 120, which is the ideal bond angle (because lone pair pushes on bonded pairs with more force)

Why are some bond angles smaller than the ideal bond angles

The presence of a lone pair (Lone pairs occupy more space. They exert a stronger force of repulsion that a bonded pair)

Molecular shape: AX4 # of electron pairs around central atom? Shape? Bond Angles?

4 Tetrahedral 109.5

Molecular shape: AX3E # of electron pairs around central atom? Shape? Bond Angles?

3 bonding, 1 lone Trigonal pyramidal Less than 109.5

Molecular shape: AX2E2 # of electron pairs around central atom? Shape? Bond Angles?

2 bonding, 2 lone Bent, angular Less than 109.5

When labelling bond angles that are “less than” where do you always draw the arrow in between

2 bonding pairs (Instead of a bonding pair and lone pair)

Molecular shape: AX5 # of electron pairs around central atom? Shape? Bond Angles?

5 bonding Trigonal bipyramidal 120 degrees

Molecular shape: AX4E # of electron pairs around central atom? Shape? Bond Angles?

4 bonding, 1 lone See saw Smaller than 120 and 90

Molecular shape: AX3E2 # of electron pairs around central atom? Shape? Bond Angles?

3 bonding, 2 lone T shape Less than 90

Molecular shape: AX2E3 # of electron pairs around central atom? Shape? Bond Angles?

2 bonding, 2 lone Linear 180 degrees

Molecular shape: AX6 # of electron pairs around central atom? Shape? Bond Angles?

6 bonding Square pyramidal 90 degrees

Molecular shape: AX5E # of electron pairs around central atom? Shape? Bond Angles?

5 bonding, 1 lone Square pyramidal Less than 90 degrees

Molecular shape: AX4E2 # of electron pairs around central atom? Shape? Bond Angles?

4 bonding, 2 lone Square planar 90 degrees

What is electron group arrangement

Only considers how many THINGS the central atom is connected to (other atoms and lone pairs)

How to determine electron group arrangement shape

1) determine type (AXE thing) 2) add up the subscripts of X and E and March that number to the corresponding shape linear= 2 trigonal planar= 3 Tetrahedral= 4 Trigonal bipyramidal= 5 Octahedral= 6

Valence Bond Theory: a _____bond is formed when atomic orbitals ______ and a pair of electrons is ______ in the region between the atoms (The mixing of atomic orbitals to produce ____ orbitals)

Covalent Overlap Localized Hybrid

Steps for using Valence Bond Theory

1) determine # of required hybrid orbitals -look at # of effective pairs around central atom 2) determine hybrid orbital -write condensed e-configuration of central atom -look at last two energy levels to see which orbitals mix -write hybrid orbital(superscript shows HOW MANY orbitals you took from that energy level)

What is a sigma bond between

Anything with p

What is a pi bond between

Only p-p

A sigma bond is the result of what kind of overlap? Where is it electron density?

End-to-end overlap of orbitals Has electron density along the axis of the bond

A pi bond is the result of what kind of overlap? Where is it electron density?

Side-to-side overlap of orbitals Has electron density BOTH above and below the axis of the bond

What is lattice energy

Energy released when anions and cations come together

Is bond formation and bond breaking exo or endothermic

Formation= exothermic Breaking= endothermic

Bond strength is related to its ____ and ____

Length and energy

What does triangle H stand for

Enthalpy change

The shorter the bond, the ____ it is, therefore the ____ the bond energy (And why)

Stronger Higher (Higher force of attraction)

Multiple bonds are STRONGER and have HIGHER bond energies why?

Because they’re shorter than single bonds

Do multiple or single bonds require more energy to break and why

Multiple bonds because they bring the atoms closer together

Molecular Orbital Theory: electrons are found in molecular orbitals which represent the _____ of electrons over the ____ molecule (Crest molecular orbitals that contain ____ the electrons)

Delocalization Entire All

When writing condensed electron configuration of an ion (so has a charge) which orbital do you TAKE AWAY electrons from (And give an example)

Take electrons out of the HIGHEST energy level (so highest numbered orbital) Ex) take electrons out of the 4s before the 3d

Black line spectra: the last line after a big black block is always n= ____

Infinite

Black line spectra: what nf values do these correspond to? Ground state first excited state Second excited state

n=1 n=2 n=3

Black line spectra: How to determine the n initial of the FIRST line (And give an example)

First line always has a numerical difference of 1, so determine n final based on words give and add one Ex) “second excite state” so n final=3 so n initial of the first line is 4

What is a metallic hydride

Hydrogen bonded to a TRANSITION METAL

What is an ionic hydride

Hydrogen bonded to an S-BLOCK element

What is a covalent hydride

Hydrogen bonded to a NON-METAL

When counting for condensed electron configuration do you INCLUDE the element that you want in you counting

YES

How to determine bond order in MO’s

Bond order= (# of e on BMO- # of e on ABMO)/2

What property does stability correspond to and what does this mean

Bond order Fractional bond order ISN’T stable

# of molecular orbitals formed is always ____ to the # of atomic orbitals that are combined

Equal

The combination of ____ atomic orbitals gives one BMO and ___ ABMO

2 1

Bond order is a measure of ____ ____

Bond strength

What happens if bond order is 0

No bond exist, so atom isn’t formed

Trend in bond length: Bond length increases= ____ bond = _____ BO

Weaker Smaller

3 reasons why hydrogen is different from other elements of group 1

1) is a non metal 2) forms covalent bonds with non metals 3) forks ionic hydrides with metals and metallic hydrides with transition metals

What are H3O+ and OH- called

Hydronium and hydroxyl

What is an Arrhenius acid (And what must it contain)

Compound that increases the concentration of H3O+ in solution Must contain an ionizable H in the structure

What is an Arrhenius base (And what must it contain)

Compound that increases the concentration of OH- ions in solution Must contain an ionizable OH on the structure

What is a BL acid

Compound that can donate a proton (H+)

What is a BL base

A proton acceptor

What is a Lewis acid (And what do they either have)

Compound that accepts an electron pair Either have: 1) a polarized bond to hydrogen, so they lose a proton, H+ 2) have empty orbitals into which they can accept electrons

What is a Lewis base to

Has atom(s) with non bonding electrons (lone pairs) which they can donate

A strong acid in water will ionize _______ A weak acid in water will ionize ______ (remember arrows)

Completely Partially

HOW MANY VALENCE ELECTRONS DOES HYDROGEN HAVE when drawing lewis structures