Topic 3 - structure and bonding

Question 1

What is ionic bonding

Answer 1

Ionic compounds being held together by strong forces of attraction between their oppositely charged ions.

Question 2

What are the particles like in a solid?

Answer 2

• packed close together
• vibrate around in fixed positions

Question 3

What are the particles like in a liquid?

Answer 3

• close together but can slip and slide over eachother in a random motion

Question 4

What are the particles like in a gas?

Answer 4

Lots of space between them and zoom around randomly

Question 5

Why do the simple particle models have limitations?

Answer 5

The atoms, molecules and ions that make up all substances are not solid spheres with no forces between them

Question 6

Elements form compounds by…

Answer 6

…Gaining or losing electrons by sharing electrons

Question 7

Name the groups and what ions they form

Answer 7

• group 1 forms 1+ ions
• group 2 forms 2+ ions
• group 3 forms 3+ ions
• group 4 don’t form ions (except Sn and Pb)
• group 5 forms 3- ions
• group 6 forms 2- ions
• group 7 forms 1- ions
• group 0 never forms ions

Question 8

Why will ionic compounds conduct electricity when molten or dissolved in water?

Answer 8

Their ions can then become mobile and can carry charge through the liquid

Question 9

Why do ionic compounds have high melting points?

Answer 9

It takes a lot of energy to break the strong ionic bonds, operating in all directions, that hold a giant ionic lattice together

Question 10

When are covalent bonds formed?

Answer 10

When atoms of non-metals share pairs of electrons with each other

Question 11

Many substances containing covalent bonds consist of s……… m…………….. but some have g……. c…………. structures

Answer 11

Simple molecules, giant covalent

Question 12

Substances made up of simple molecules have ……… melting and boiling points

Answer 12

Low

Question 13

Why do the substances of simple molecules have low melting and boiling points?

Answer 13

Because the intermolecular forces between them are weak

Question 14

Simple molecules have no overall charge so they can’t what?

Answer 14

They can’t carry electrical charge and cannot conduct electricity

Question 15

Giant covalent substances have very ……. melting and boiling points

Answer 15

High

Question 16

Why is graphite soft and slippery?

Answer 16

It contains giant layers of covalently bonded carbon atoms, however there aren’t any covalent bonds between the layers meaning they can slide over eachother.

Question 17

What is a diamond like, in terms of atomic structure?

Answer 17

The carbon atoms have a rigid giant covalent structure, therefore diamonds are a very hard substance

Question 18

Why can graphite conduct thermal energy and electricity?

Answer 18

Because of the delocalised electrons that can move along it’s layers

Question 19

Describe fullerenes

Answer 19

• large, cage-like structures and tubes based on hexagonal rings of the carbon atoms

Question 20

What can fullerenes be used for?

Answer 20

• transport mechanism for drugs to specific sites in the body
• as catalysts
• reinforcement for composite materials

Question 21

Why can metals be bent and shaped?

Answer 21

The layers of atoms (positively charged ions) in a giant metallic structure can slide over each other

Question 22

What are alloys like and why?

Answer 22

• harder than pure metals because the regular layers are distorted by atoms of different sizes in an alloy

Question 23

Why do nano particles have properties different for the same materials in bulk?

Answer 23

Because nano particles have a high SA:V ratio, with high percentage of atoms exposed at the surface

Question 24

What is nano science?

Answer 24

The study of small particles between 1 and 100 nanometres in size