2 Bonding 3 Flashcards

1
Q

Describe the main features of metals in terms of their structure

A

Positive metal ions arranged in layers with delocalised electrons

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2
Q

Explain why metals can conduct electricity

A

Delocalised electrons are free to carry charge

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3
Q

Explain why pure metals are soft

A

Layers of metal ions are free to slide over each other

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4
Q

What is an alloy?

A

A mixture of two or more elements, at least one of which is a metal

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5
Q

Give a reason for alloying a metal

A

To make it harder, to make it less reactive

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6
Q

Explain why alloys can be harder than pure metals

A

Different size of atoms disturb the layers to stop them sliding over each other

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7
Q

What are the three types of chemical bond?

A

Ionic, covalent and metallic

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8
Q

Which type of bonding involves electrostatic attractions between oppositely charged ions?

A

Ionic

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9
Q

What is the definition of a covalent bond?

A

A shared pair of electrons

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10
Q

Why is aluminium a better electrical conductor than sodium?

A

Aluminium is in group 3, so each atom contributes 3 electrons to the delocalised sea of electrons, leaving behind a 3+ ion. There are more electrons in the sea than sodium, so it is a better conductor.

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11
Q

Why are alloys stronger than pure metals?

A

There are different sized atoms in the structure which distorts the layers and stops them being able to slide over each other.

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12
Q

Put these bonds in order of strength starting with the weakest: ionic, covalent, metallic

A

Weakest metallic, then ionic, covalent strongest

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13
Q

How does the charge on the ions produced by the metals in groups 1, 2 and 3 relate to their group number?

A

It is positive and the same as the group number

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14
Q

How the charge on the ions produced by the non-metals in groups 5, 6 and 7 realte to their group number.

A

It is equal to the group number minus 8.

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15
Q

Describe the structure of sodium chloride and explain why it has a high boiling point.

A

It is a 3D lattice of 1+ sodium ions and 1- chloride ions. The electrostatic force between the oppositely charged ions is high, so the bonds are strong. There are many bonds. A lot of energy is needed to overcome the ionic bonds.

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16
Q

What type of structures do water, ammonia and iodine have?

A

Simple molecular (or simple molecules)

17
Q

What are the three states of matter?

A

solid, liquid and gas

18
Q

What type of bonds hold the long chain together in polymers?

A

Covalent

19
Q

How many bonds does each carbon have in graphite?

A

3

20
Q

What is graphene made from? Describe its structure.

A

A single layer of carbon atoms in a graphitre structure.

21
Q

Ammonia is a liquid between -77.7 oC and
-33.3oC. Use the kinetic theory to explain
the three states of matter in this case.

A

Below -77.7 degrees the particles are close together and only vibrate, ammonia is a solid. If the temperature is above -77.7 degrees but below -33.3 the particles are close together but able to move, ammonia is a liquid. Above -33.3 the forces between the molecules have been overcome and they are free to move around, ammonia is a gas.

22
Q

Diamond coating would make smartphones and tablets far stronger but would remove their touch-screen capability. Use your knowledge of bonding to explain why.

A

Diamond is a giant covalent structure. All the electrons are shared in bonds and not able to move and carry charge. If the screen has a diamond coating it cannot conduct and will not work.

23
Q

Explain why the ball and stick model is not a true representation of the structure of an ionic compound.

A

The ions are not spread apart they are close together, so the sticks are misleading. The ions are not always ball shaped and may be different sizes, so the balls are also misleading.

24
Q

Sulphur hexafluoride SF6 is an insulating gas. Suggest the type of bonding present and explain why it is gaseous at STP (Standard Temperature and Pressure).

A

Covalent bonding as S and F are non-metals. There ould be weak intermolecular forces between each molecule.