5.3 covalent bonding Flashcards

1
Q

define

covalent bond

A

The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded
atoms.

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2
Q

where does covalent bonding taker place

A

Covalent bonding takes place in diatomic elements, in compounds of non-metallic elements,
and between the atoms of polyatomic ions

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3
Q

explin what is meant by a localsied bond

a covlent bond is an example of a……

A

Localised bond

Unlike ions in an ionic bond, which attract in all directions, a covalent bond has an attraction
that is localised. The attraction acts solely between the shared pair of electrons.

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4
Q

how many bonds do these elements form

C,O,N,H

A

Carbon forms 4 bonds

Nitrogen forms 3 bonds

Oxygen forms 2 bonds

Hydrogen forms 1 bond

This allows each of these elements to have a filled outer shell, and thus obey the octet rule –
giving them a greater stability and allows them to resemble the desired noble gas configuration.

However, there are exceptions to the rule: Boron, Phosphorous, Sulfur and Chlorine.

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5
Q

4 exceptions to the octect rule

A

Boron, Phosphorous, Sulfur and Chlorine.

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6
Q

Boron exception:

A

Boron has 3 electrons in the outer shell, and each pair up to form 3 bonding pairs. In total this gives Boron 6 electrons inthe outer shell.

This is a deviance from the otherwise desired 8 – but Boronis stable in this arrangement.

BF3 (boron trifluoride) is trigonal planar.

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7
Q

exception Phosphorous, Sulfur and Chlorine.

A

Phosphorous, Sulfur and Chlorine.

Phosphorous, sulfur and chlorine when bonding with (mainly) fluorine can gain that idea of 8
electrons in its outer shell (full 3p orbital)

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8
Q
A
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