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 (sodium chloride - salt)

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3
Q

How high are ionically

bonded substances’ bp and mp? 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 when solid)

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5
Q

What is simple molecular

covalent bonding?

A

Strong covalent bonds between atoms, weak van der 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 der 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 bpts? 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 four others

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13
Q

Describe the structure

of graphite

A

Similar to diamond - macromolecular covalent - but each C atom is only bonded to 3 others, so it is in layers
Weak van der Waals forces of attraction between layers mean they can slide over each other → soft, slippery
One electron from each carbon is delocalised and can carry charge → conducts electricity

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14
Q

Describe metallic bonding

A

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

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15
Q

Do metallic compounds
have high/low bpt and
mpts? 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 charge

17
Q

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

A

Increases → higher melting and boiling points, stronger
Higher charge on metal ions
More delocalised electrons per ion
Stronger force of attraction between them

18
Q

Define electronegativity

A

The ability of an atom to attract the pair of electrons (the electron density) in a covalent bond

19
Q

What affects electronegativity? (3)

A

Nuclear charge
Atomic radius
Electron shielding

20
Q

What is the most

electronegative element?

A

Fluorine (4.0 on Pauling’s scale) → largest nuclear charge for its electron shielding, small atomic radius

21
Q

How do you get a nonpolar bond?

A

Both bonding elements have the same

electronegativities

22
Q

When do you get a polar bond?

A

Bonding atoms have different electronegativities

23
Q

What is the strongest type of IMF?

A

Hydrogen bonding

24
Q

What is the weakest type of IMF?

A

van der Waals forces

25
Describe van der Waals’ forces of attraction.
Temporary dipoles are created by the random movement of electrons → induces dipole in neighbouring molecule → temporary induced dipole-dipole attraction aka van der Waals forces of attraction
26
Are Van der Waals forces greater in smaller or 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 those 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, N and F are highly electronegative, H nucleus is left exposed
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 liquid water
30
What is a dative | covalent bond? When is it formed?
Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion 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 in bonded or lone pairs
32
What does the Electron Pair Repulsion Theory state?
that electron pairs will take up positions as far away from each other as possible, to minimise the repulsive forces between them
33
Which experience the most repulsion? | LP-LP, LP-BP, BP- BP
LP-LP repulsion strongest LP-BP repulsion middle BP-BP repulsion weakest
34
What is the shape, and bond angle in a shape with 2 bonded pairs and 0 lone pairs?
Linear | 180°
35
What is the shape, and bond angle in a shape | with 3 bonding pairs and 0 lone pairs?
Trigonal planar | 120°
36
What is the shape, and bond angle in a shape | with 4 bonded pairs and 0 lone pairs?
Tetrahedral | 109.5°
37
What is the shape, and bond angle in a shape with 5 bonded pairs and 0 lone pairs?
Trigonal bipyramid | 90° and 120°
38
What is the shape, and bond angle in a shape | with 6 bonded pairs and 0 lone pairs?
Octahedral | 90°