4. Covalent bonding Flashcards

1
Q

Why do elements take part in reactions?

A
  • To achieve a full outer shell
  • To achieve a stable electron arrangement
  • To achieve a noble gas electron arrangement
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2
Q

How do non-metal atoms achieve a full outer shell when they react with one another?

A

They share unpaired electrons.

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3
Q

What is a covalent bond?

A

A shared pair of electrons

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4
Q

What holds the atoms together when they form covalent bonds?

A

The common (electrostatic) attraction the nuclei have for the shared pair of electrons.

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5
Q

What is a molecule?

A

2 or more atoms joined by covalent bond(s)

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6
Q

What do we call the attractions between molecules?

A

Intermolecular attractions

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7
Q

Are intermolecular bonds strong or weak?

A

Weak

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8
Q

What happens when we melt or boil substances composed of molecules?

A

We break the weak intermolecular attractions

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9
Q

What is an orbital diagram?

A

Normally 4 lobes as shown in diagram with ONLY the outer electrons shown. it shows the arrangement of ALL outer electrons in the molecule

The diagram is for a Cl atom

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10
Q

What is meant by valency?

A

The number of unpaired electrons an atom has in its outer (valence) shell.

In the example shown for Cl , only 1 electron is unpaired so the valency is 1

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11
Q

Why do covalent compounds not conduct electricity:?

A

Because the molecules or networks do not carry any overall charge.

The total number of protons and electrons are equal

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12
Q

Why do covalent network substances have high melting points?

A

Because you have to break a lot of strong covalent bonds.

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13
Q

Why do covalent molecular substances have low melting and boiling points?

A

Because you only have to break weak intermolecular attractions

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14
Q

What type of bonding is shown in the diagram?

A

Covalent molecular

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15
Q

What type of bonding is shown?

A

Covalent network

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16
Q

Name 2 covalent network structures

A

Diamond (Carbon) : Element

Silicon Dioxide (Si O2 ) : Compound

17
Q

Name the 7 diatomic covalent molecular elements

A

Iodine

Hydrogen

Nitrogen

Bromine

Oxygen

Chlorine

Fluorine

18
Q

What are the 4 molecular shapes we need to know?

A
  • Linear
  • Angular
  • Trigonal Pyramidal
  • Tetrahedral
19
Q

Which shape do all diatomic molecules have:?

A

Linear

20
Q

Which shape does water have?

A

Angular

21
Q

Which shape does ammonia (Nitrogen hydride) have?

A

Trigonal Pyrimidal

22
Q

Which shape does Methane have?

A

Tetrahedral