CaF2; ionic solid; metallic solid Flashcards

1
Q

what is the cation: anion ratio of CaF2

A

1:2

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2
Q

true or false; the fcc array of Ca(2+) ions with F(-) ions occupy all tetrahedral sites

A

true

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3
Q

what is the formula for the general structure of salts; with generally large cations and generally small anions

A

MX2

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4
Q

how many Ca(2+) ions in CaF2

A

4

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5
Q

how many F(-) ions in CaF2

A

8

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6
Q

true or false; the ions sitting at the holes of the lattice (fcc or cubic) are bigger than the holes themselves

A

true

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7
Q

what is the effect, when the ions are bigger than the holes

A

this causes the expanding of the lattice and reducing contacts between ions of like charge

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8
Q

true or false; when the size of the hole decreases, the size of the ions surrounding the hole decreases

A

true

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9
Q

what is the radius of a sphere that fits the tetrahedral hole

A

0.2

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10
Q

what is the radius of the sphere that fits the octahedral hole

A

0.4

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11
Q

what is the radius of a sphere that fits the cubic hole

A

0.7

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12
Q

In ionic solids what causes the high lattice energy?

A

the fixed ion positions are bonded to each other with very strong interionic (electrostatic) forces

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13
Q

is the mp of an ionic solid high or low?

A

high

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14
Q

why do ionic solids have low electrical conductivity in the solid state?

A

the ions are not free to move thus they cannot conduct electrical charge

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15
Q

why are ionic solids hard?

A

because only strong external forces can change the relative positions of trillions of interaction ions

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16
Q

why does an ionic solid crystal crack

A

when enough force is applied to move them, like ions are brought close together and their repulsions crack the crystal

17
Q

when a force is applied to a metallic solid, what happens?

A
  • metals bend

- metals are deformed

18
Q

true or false; metals are able to conduct heat and electricity in both solid and liquid states?

19
Q

what STRONG forces hold metal atoms together

A

metallic bonding forces

20
Q

how does the strong metallic bonding forces influence the mp and bp of a metallic solid

A

they are both high

21
Q

what is the simplistic way of viewing the bonding in metals?

A

all metals in a sample contribute their valence electrons to form an “electron sea” that is DELOCALIZED throughout the sample

22
Q

true or false; the metal atoms (minus their valence electrons) form a regular array WITHIN this “sea” of electrons

23
Q

true or false; no metals atoms are bonded through a localized pair of electrons

24
Q

meaning of localized electrons

A

electrons that are not in the valence band or conduction band; rather in the inner shell electrons

25
meaning of delocalized electrons
electrons shared among the crystal or molecule and will form part of the energy band
26
what properties of metals do the electron sea model account for
- regularity (but not rigidity) of metal atom array | - mobility & delocalized nature of valence electrons
27
what happens when force is applied to a metallic solid?
the metal ions slide past each other through the electron sea to new lattice positions
28
why are metals good conductors of electricity?
because they have mobile electrons
29
why are metals good conductors of heat
because of their mobile electrons
30
what does the molecular orbital band theory describe
the bonding in metals, metalloids, non metals