1.3 Bonding Flashcards

1
Q

What is ionic bonding

A

Strong electrostatic forces of attraction between oppositely charged ions held in a lattice

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2
Q

Give an example of an ionically bonded substance

A

NaCl

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3
Q

How high are ionically bonded substances mp and bp? Why?

A

High - takes lots of energy to break strong electrostatic forces of attraction between oppositely charged ions

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4
Q

Do ionic compounds conduct electricity? Why?

A

Yes, when molten / in solution as the ions are free to move and carry charge (don’t conduct when solid)

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5
Q

What is simple molecular covalent bonding?

A

Strong covalent bonds between atoms, weak Van de Waals forces of attraction between molecules

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6
Q

Are there any lone electrons in simple covalent bonding

A

No - all involved in bonding

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7
Q

Can simple molecular covalent molecules conduct electricity? Why?

A

No - all electrons used in bonding and aren’t free to move

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8
Q

Do simple molecular substances have a high/low mpt and bpt? Why?

A

Low - weak van de Waals forces of attraction between molecules that don’t take much energy to overcome (these are overcome rather than covalent bonds)

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9
Q

Describe macromolecular covalent bonding

A

Lattice of many atoms held together by strong covalent bonds

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10
Q

Do substances with macromolecular covalent bonds have high/low mpt and bpt ? Why?

A

High, as it takes a lot of energy to overcome many strong covalent bonds

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11
Q

Do substances with macromolecular covalent bonds conduct electricity?

A

Most don’t as all electrons are used in bonding

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12
Q

Describe the structure of diamond

A

3D tetrahedral structure of C atoms with each C atom bonded to 4 others

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13
Q

Describe the structure of graphite

A

Similar to diamond but each atom is only bonded to 3 others so it is in layers
Weak van de Waals forces of attraction between layers allow them to Slide Over each other —> soft and slippery
One electron of each carbon is delocalised and can carry charge —> can conduct electricity

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14
Q

Describe metallic bonding

A

Lattice of positive metals ions strongly attracted to a sea of delocalised electrons. Layers slide over each other - malleable

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15
Q

Do metallic compounds have high mpt / bpt ? Why ?

A

High as strong forces of attraction between positive metal ions and negatively charged sea of delocalised electrons

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16
Q

Do metallic compounds conduct electricity ? Why?

A

Yes as delocalised electrons can move throughout the metal to carry charges

17
Q

How does the strength of metallic bonding change across the periodic table? Why?

A

Increases - higher mpt and bpt, stronger
Higher charge on metal ions
More delocalised electrons per metal ion
Stronger forces of attraction between

18
Q

Define electronegativity

A

The ability of an atom to attract a pair of electrons in a covalent bond

19
Q

What affects electronegativity ? (3)

A

Atomic radius
Nuclear charge
Electron shielding

20
Q

What is the most electronegative element?

A

Fluorine (F) - 4.0 on paulings scale
Largest nuclear charge for its electron shielding, smallest atomic radius

21
Q

How do you get a non-polar bond?

A

Both bonding elements have the same electronegativity

22
Q

When do you get a polar bond?

A

When both bonding atoms have different electronegativity

23
Q

What is the strongest form of inter-molecular force?

A

Hydrogen bonding

24
Q

What is the weakest form of intermolecular force?

A

Van de Waals forces

25
Describe Van de Waals forces of attraction
Temporary dipole is created by random movement of electrons —> induces dipole in neighbouring molecule —> temporary induced dipole dipole attraction aka Van de Waals forces of attraction
26
Are Van de Waals forces greater or smaller in larger molecules
Larger - more electrons
27
Describe permanent dipole-dipole attraction
Some molecules with polar bonds have permanent dipoles —> forces of attraction between those dipoles and the dipoles of neighbouring molecules
28
What conditions are needed for hydrogen bonding to occur?
O-H, N-H or F-H bond, lone pair of electrons on O, F, N Because O, F and N are highly electronegative, H nucleus is left exposed Strong force of attraction between H nucleus and lone pair of electrons on O, F or N of a neighbouring molecule
29
Why is ice less dense than liquid water
In liquid water, hydrogen bonds constantly break and reform as molecules move about In ice, the hydrogen bonds hold the molecules in fixed positions; this makes them slightly further apart than in water, making ice less dense than water
30
What is a dative/ coordinate covalent bond? When is it formed?
Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom with a lone pair of electrons (not used in bonding)
31
What does the shape of molecules depend on?
Number of electrons in the valence shell of the central atom Number of these electrons which are bonded or in lone pairs
32
What does the electron pair repulsion theory state?
That electrons will take up positions as far away from each other as possible, to minimise the repulsive forces between them
33
Which experience the strongest repulsion Lone pair - lone pair Lone pair - bonded pair Bonded pair - bonded pair
LP-LP strongest repulsion LP-BP middle repulsion BP-BP weakest repulsion
34
What is the shape, diagram and bond angle in a shape with 2 bonded pairs and 0 lone pairs?
Linear 180 degrees •—•—•
35
What is the shape, diagram and bond angle in a shape with 3 bonded pairs and 0 lone pairs
Trigonal planar 120 degrees
36
What is the shape, diagram and bond angle in a shape with 4 bonded pairs and 0 lone pairs?
Tetrahedral 109.5 degrees
37
What is the shape diagram and bond angle in a shape with 5 bonded pairs and 0 lone pairs
Trigonal bipyramid 90 and 120 degrees
38
What is the shape diagram and bond angle in a shape with 6 bonded pairs and 0 lone pairs
Octahedral 90 degrees