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chemistry > 4.1 Covalent Bonding > Flashcards

4.1 Covalent Bonding Flashcards

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1
Q

Define covalent bonding

A

Covalent bonding is the electrostatic attraction between protons in two nuclei and a shared pair of of electrons between them

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2
Q

Covalent bonds are formed between…

A

Non metals (share pairs of electrons to get a fully outer shell)

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3
Q

What is the process for determining the sharing of atoms in molecules with double or triple pairs? For e.g. what happens when S and F share?

A
  • S has 6 in the outer-shell = needs to share two pairs
  • F has 7 in the outer-shell = needs to share one pair
  • So we need 2 x F and 1 x S
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4
Q

What is a simple molecule?

A

A small group of atoms held together by covalent bonds.

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5
Q

Is covalent bonding a strong or weak attraction?

A

Covalent bonding is a very strong attraction.

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6
Q

What do the shared pair of electrons do to the nuclei of the atoms? (covalent bonding)

A

The shared pair of electrons effectively pull the nuclei of the atoms closer together

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7
Q

What happens when simple molecular substances boil?

A

Weak intermolecular forces (IMFs) break between the molecules.

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8
Q

As molecular mass increases, what happens to the strength of weak intermolecular forces (IMFs)?

A

The strength of weak intermolecular forces (IMFs) increases. This results in the boiling point increasing.

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9
Q

Why don’t simple molecular substance conduct electricity?

A

Simple molecular substances do not conduct electricity because they lack charged particles necessary (molecules are neutral) for electrical conductivity.

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10
Q

C60 fullerene

A

C60 fullerene is a unique simple molecule composed of sixty carbon atoms in a ball.

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11
Q

What are properties of C60 fullerene?

A

Formula: C60
Molecular Mass: 720
Boiling Point: Above +600°C
Physical State: Soft and slippery solid
Electrical Conductivity: Insulator

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12
Q

Why is C60 fullerene a soft slippery solid?

A

-Because molecules can roll over eachother easily

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13
Q

Why is C60 an electrical insulator?

A

-Because the molecules are neutral

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14
Q

What is diamond?

A

Diamond is a form of pure carbon arranged into a giant lattice.

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15
Q

Why does diamond sublime at a high temperature?

A
  • Covalent bonds are very strong
  • There are lots of bonds in the giant lattice
  • Lots of energy is required to break all the bonds
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16
Q

Why can’t diamond conduct electricity?

A

-because there are no freely-moving charged particles.
-All the atoms are neutral
-and all the electrons are stuck inside an atom or a bond

17
Q

What is diamond used in and why?

A

-Used in cutting
-It is one of the hardest substances

18
Q

What are the characteristics of diamond’s lattice structure?

A
  • Every C makes 4 covalent bonds
  • Tetrahedral shape
  • Strong, grid-like arrangement
19
Q

What is graphite?

A

Graphite is another form of pure carbon arranged into a giant lattice.

20
Q

Why can graphite conduct electricity?

A

-Because inside the layers
-The delocalised electrons can move freely

21
Q

Why does graphite sublime at a very high temperature?

A

(For the same reasons as diamond)
* Covalent bonds are very strong
* There are lots of bonds in the giant lattice
* Lots of energy is required to break all the bonds

22
Q

What are the characteristics of graphite’s lattice structure?

A
  • Layers of hexagons of C atoms
  • Every C makes 3 covalent bonds (red)
  • Weak intermolecular forces (IMFs) between layers (blue)
  • Delocalised electrons inside each layer
23
Q

What is graphite used in and why?

A

-Used as a solid lubricant
-It is soft and slippery because the layers can slide easily

24
Q

What is silicon dioxide?

A

Silicon dioxide (SiO2) is also known as silica and has a giant covalent structure.

25
Q

What are the characteristics of silicon dioxide’s lattice structure?

A
  • Every Si makes 4 covalent bonds (black)
  • Every O makes 2 covalent bonds (red)
  • Tetrahedral shape (like diamond)
  • Strong, grid-like arrangement
26
Q

What properties of silicon dioxide are similar to diamond?

A

-Share similar bonding and structure.

27
Q

Why is silicon dioxide much less expensive compared to diamond?

A

-It is much less rare.

28
Q

What is the bonding ,structure and properties of Metal + Non-metal?

A

Bonding: Ionic
Structure: Giant lattice
Essential properties: -High MP/BP
-Insulator when (s)
-Conductor when (l)
-Conductor when (aq)
Other properties: -Brittle
-Usually soluble in water
-Crystalline

29
Q

What is the bonding ,structure and properties of only Non-metals?

A

Bonding: Covalent
Structure: Simple molecules
Essential properties: -Low MP/BP
-Insulator
Other properties: -Usually insoluble in water
-Dull

30
Q

What is the bonding ,structure and properties of only Metals?

A

Bonding: Metallic
Structure: Giant lattice
Essential properties: -High MP/BP
-Conductor
Other properties: -Malleable
-Ductile
-Shiny

31
Q

Why do melting and boiling points of substances with simple molecular structures increase, in general, with increasing relative molecular mass?

A

-Larger molecules have more mass and more forces of attraction between them
-These forces, though weak, must be overcome for the substance to boil
-Larger molecules possess more attractions that need to be overcome

32
Q

Do covalent compounds conduct electricity?

A

Covalent compounds do not conduct electricity

33
Q

Explain the trend in reactivity in Group 7 in terms of electronic configurations

A

-Reactivity increases up Group 7 (halogens) of the periodic table.
-Halogens readily form ions by attracting passing electrons to fill their outer shell.
-Fluorine’s outer shell is close to the nucleus, resulting in strong attraction and high reactivity.
-lodine’s outer shell is farther from the nucleus, leading to weaker attraction and lower reactivity.

chemistry (10 decks)

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