Chapter 8 Flashcards by ghita moustaki

What is the difference between trigonal planar and trigonal pyramidal

trigonal planar doesn’t have lone pairs on the central atom

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what group tends to have trigonal planar arrangements

group 3

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what group tend to have trigonal bipyramidal arrangements

group 5

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What is the electron arrangement of a molecule with 4 e- pairs around the central atom

tetrahedral

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What is the electron arrangement
of a molecule with 3 e- pairs around the central atom

trigonal planar

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What is the electron arrangement
of a molecule with 2 e- pairs around the central atom

linear

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What is the electron arrangement
of a molecule with 5 e- pairs around the central atom

trigonal bipyramidal

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What is the electron arrangement
of a molecule with 6 e- pairs around the central atom

octahedral

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Geometric arrangement of a molecule with 2 sigma bonds and no lone pair

linear

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Why are double and triple bonds considered as one in the VSPER theory

Only sigma bonds are considered and there’s only on in each multiple pair; the other bonds are pi bonds

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Geometric arrangement of a molecule with 3 sigma bonds and 0 lone pairs

trigonal planar

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Geometric arrangement of a molecule with 2 sigma bonds and 1 lone pair

angular/bent

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Geometric arrangement of a molecule with 4 sigma bonds and 0 lone pair

tetrahedral

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Geometric arrangement of a molecule with 3 sigma bonds and 1 lone pair

trigonal pyramidal

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Geometric arrangement of a molecule with 2 sigma bonds and 2 lone pairs

angular/bent

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Geometric arrangement of a molecule with 5 sigma bonds and 0 lone pair

trigonal bipyramidal

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Geometric arrangement of a molecule with 4 sigma bonds and 1 lone pair

irregular tetrahedral/see-saw

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Geometric arrangement of a molecule with 3 sigma bonds and 2 lone pair

T-shaped

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Geometric arrangement of a molecule with 2 sigma bonds and 3 lone pair

linear

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Geometric arrangement of a molecule with 6 sigma bonds and 0 lone pair

octahedral

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Geometric arrangement of a molecule with 5 sigma bonds and 1 lone pair

square pyramidal

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Geometric arrangement of a molecule with 4 sigma bonds and 2 lone pair

square planar

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What is the bond angle between 2 e- pairs in a linear arrangement?

180 degrees

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What is the bond angle between 3 e- pairs in a trigonal planar arrangement?

120 degrees

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What is the bond angle between 4 e- pairs in a tetrahedral arrangement?

109.5 degrees

What is the bond angle between 5 e- pairs in a trigonal bipyramidal arrangement?

90 degrees between the vertical and horizontal plane 120 degrees between the electrons in the horizontal plane

What is the bond angle between 6 e- pairs in an octahedral arrangement?

90 degrees between all pairs

What is the bond angle in a water molecule

104.5 degrees

how does the bond angle change in a molecule with lone pairs and why?

the angle of the respective electron arrangement reduces since lone pairs require more space

Define chemical bond

the strong attractive force between certain atoms in a substance

Whats the difference between an ionic and covalent bond

ionic bonds are formed by a transfer of e- in a cation and anion in a molecule. A covalent bond is formed by sharing a pair of e-

Define bonding pair

electron pair between two atoms, represented by one line

Define lone pair

electron pair that are nonbonding

What rule do atoms obey when forming bonds and why

atoms except hydrogen ten toward the octet rule to become more stable

Define polar covalent bond

unequal sharing of electrons between atoms in molecule=charge separation in bond charge oriented towards an electric field

Define electronegativity

measure of the ability of an atom to draw bonding electrons to itself

What characteristic is related to electronegativity

ionization energy and electron affinity

Define polar bond

covalent bond where bonding electrons spend more time near one atom than near the other atom

How does electronegativity increase and why

it increases from left to right and bottom to top

what elements are the most electronegative

F, O, N, and CL

What's the link between polarity and electronegativity? what does it represent

the difference between 2 atoms in a bond = measure of bond polarity large difference= ionic or polar bond small difference= nonpolar bond

Define Dipole moment

A molecule whose charge can be represented by center positive and center negative, where a net vector is present positive center is least electronegative while negative is most electronegative

what do vectors that cancel out mean

no net dipole moment

Are bonds more polar when parallel or perpendicular to the trend

Parallel

How does an anion compare to its parent atom and why?

Anion is bigger since e- is added

How does a cation compare to its parent atom and why?

Cation is smaller, since removal e-

What's an Isoelectronic series

Serie of ions or atoms containing the same number of electrons

How do you determine the central atom

least electronegative atom is central atom H\F are never central atoms

what are the exceptions to the octet rule

H has 1 e- pair C, O, N, F have 4 e- pairs Be has 2 e- pairs B, Al, Sn have 3 e- pairs

what conditions need to be respected when distributing the remaining electrons?

H is always surrounded by 2 electrons Be is always surrounded by 4 e- B is always surrounded by 6 e- C, O, N, F are always surrounded by 8 e- other atoms can have 8 or more e-

Why cant element of the second period expand their octet

they only have s and p orbitals= can't expand their electron configuration

What do we call more than one valid Lewis structure that can be written for a molecule

resonance structures

How can you obtain the hypothetical charge of an atom

with equation: F=V-B/2-L

How can a molecule be more stable

when all formal charges are similar

True or False the sum of the formal charges of all atoms in a given molecule/ion must equal to overall charge on that species.

true

Why can e- move around a molecule

they're delocalized

Are noble gases electronegative?

What does VSEPR stand for ?

Valence Shell Electron Pair Repulsion

what are the rules when assigning the formal charges

1) all FC must be similar to have a stable compound 2) the most electronegative electrons must have the most negative FC 3) the structure with the lowest FC in magnitude must be prioritized 4) the sum of all FC must equal the charge of the species 5) FC of an atom must be as close as possible to 0

what molecular arrangement give molecules no net dipole and why is that

linear/ trigonal planar/ tetrahedral all vectors cancel eachother out

how to achieve a stable compound

make sure that atleast one atom has a noble gas electronic configuration.

whats the trend is ion sizes

for metal: bigger down a group and smaller in a period for non metals: bigger both ways since add electrons

explain the localized electron model

electron pairs are localized on aparticular atom aka central atom