C3.6 - Structure Of Simple Molecules (Finished)

Question 1

What is the limitation of the 2D ball and stick model?

Answer 1

It does not show the true shape of a molecule (bond angles)

Question 2

What do dot and cross diagrams show?

Answer 2

Which atom electrons in bonds originally came form

Question 3

What are the problems with giant structure Models?

Answer 3

They can never accurately reflect the millions of atoms and ions bonded together. They also have the atoms and ions in them simply cut off at the ends

Question 4

How can giant structure models indicate the chemical formula of a compound?

Answer 4

They can do this by using the simplest ratio of atoms or ions in models. The could be 5 of atom A and 10 of B so the ratio would be 1:2

Question 5

Intermolecular forces ________ with the size of molecules so _______ will have _______ boiling and melting points.

Answer 5

Increase, larger, higher

Question 6

Why are melting and boiling points of simple molecules very low?

Answer 6

The intermolecular forces of attraction between the molecules are very weak. You only need to break these weak forces and not the strong covalent bonds. Since molecules can be easily parted they have very low boiling points

Question 7

Why do molecular compounds not conduct electricity when water is added or melted?

Answer 7

Because they aren’t charged since there are no free electrons or ions

Question 8

What are polymers made of?

Answer 8

They are made up of many small reactive molecules that bind to each other to form long chains with repeating sections

Question 9

What is the simplest polymer and what two atoms/ions is it made form?

Answer 9

Polyethene. It is made of Carbon and Hydrogen

Question 10

Why are polymers solid at room temperature?

Answer 10

The intermolecular forces between their molecules are larger than between simple molecules so more energy is required to break them

Question 11

How do you find the molecular formula of a polymer?

Answer 11

1) Draw the smallest repeating section called the repeating unit of a polymer
2) Write down the molecular formula of the repeating unit such as H4C3
3) put this in brackets and add an n to the end

Question 12

Name some models used to show molecules?

Answer 12

3D balla and stick, 2D ball and stick, dot and cross, displayed formula, giant structures model