Topic 2-Ionic Bonding and Structure

Question 1

What are ions?

Answer 1

Ions are charged particles, they can be single atoms or a group of atoms

Question 2

Why are electrons important?

Answer 2

Electrons are important because different electron configurations mean different level of bonding

Question 3

How are ions formed?

Answer 3

Ions are firmed when atoms los or gain electrons. They do this to become. stable and have a stable electronic structure (have a full outer shell).

Metals lose electrons to form positive ions, and non metals gain electrons to form negative ions.

Question 4

What is ionic bonding?

Answer 4

This is when a metal and a non metal react together. The metal loses its electrons to form a positive ion, the non metal gains these electrons to form a negative ion.

These oppositely charged ions are strongly attached by electrostatic forces called ionic bonds

These can be represented using dot to cross diagrams

Question 5

What are ionic compounds?

Answer 5

Ionic compounds have a regular lattice structure. The ions form a regular arrangement and are held together by strong electrostatic forces going in all directions (between oppositely charged ions)
EG sodium chloride

Question 6

How can ionic compounds be represented?

Answer 6

3D model: shows you the regular pattern of the Ions, shows you the sizes of the ions however only shows the outer layer of the compound

Ball and stick model- this shows you the regular pattern of the ions and how they are arranged however doesn’t show you the masses and is not to scale

Dot to cross diagram: his shows you the electronic structure of the ions however doesn’t show you how they are arranged

Question 7

What are the properties of ionic compounds?

Answer 7

They have high melting and boiling points because they have very strong electrostatic forces so it takes a lot of energy to break the bonds.
When they are solid, they cannot conduct electricity however when they melt, ions are free to move and can carry electric current

Question 8

What is covalent bonding?

Answer 8

Covalent bonding means sharing electrons. Non metals share electrons to make covalent bonds.
They only share electrons in their outer shell as it has the highest energy level.
Each covalent bond makes one extra electron for each atom.
Covalent bonding can happen in compounds and non metals

Question 9

How can covalent bonds be represented?

Answer 9

Dot to cross diagram:
Good to show which atoms the electrons come from, however cannot show the size of the arrangement in space

Displayed formula:
Good to show how all atoms are connected however doesn’t show the sizes of them and which atoms the electrons come from

3D model:
Good to show the arrangement of the atoms however doesn’t show which atoms the electrons come from

Question 10

What are simple molecular substances?

Answer 10

Covalent bond form simple molecular substances. These are held by very strong covalent bonds however the forces of attraction between the molecules is very weak.
To melt or boil them, you only have to break the intermolecular bonds, not the covalent bonds.

They don’t conduct electricity as they have no free electrons or ions.

they have low melting and boiling points so molecules are easily broken.
As the molecule gets bigger the intermolecular forces increases, so harder to break apart

Question 11

Describe inter and intra molecular bonds:

Answer 11

Intramolecular bonds are very strong and are hard to break

Intermolecular bonds are weak bonds and are easily separated. As molecules get bigger, intermolecular forces increases

Question 12

What is a polymer?

Answer 12

polymers are long chains of repeating units. Small units are linked together to form a long molecules. these are held together by covalent bonds.
EG polyethene ( a hydrocarbon)

Question 13

What is the state of a polymer at room temp?

Answer 13

Solid

Question 14

What are giant covalent structures?

Answer 14

Giant covalent structures are macromolecules. These include GRAPHITE, DIAMOND and SILICON DIOXIDE- all made up of carbon atoms only

All of the atoms are bonded together by covalent bonds.
They have a high melting and boiling point.
They do not contain charged particles so they do not conduct electricity except for graphite.

Question 15

Describe Diamond

Answer 15

In diamond, each carbon atom forms 4 covalent bonds.
It is very hard and strong this means that it has a very high melting and boiling point.
It cannot conduct electricity because it has no free electrons or ions.

Question 16

Describe Graphite

Answer 16

In graphite, each carbon atom forms 3 covalent bonds, these are in hexagon shapes. Each carbon atom has one delocalised (free) electron so it can conduct electricity and thermal energy.
There are no covalent bonds in between the layers, they are held weakly so the layers are free to move.
This means that graphite is soft and slippery so it can be hard as a lubricator material.
It also has a high melting point so the covalent bonds in the layers are hard to break

Question 17

What is a single layer of graphite called?and describe it

Answer 17

Graphene:

it is one atom thick and can conduct electricity. it is also very light and 2 dimensional

Question 18

Describe silicon dioxide?

Answer 18

This is what sand is made of. It is one giant structure of silicon and oxygen

Question 19

What is fullerness?

Answer 19

Fullerness are molecules of carbon, shaped like tubes or hollow balls.
They are mainly arranged in hexagons, or sometimes pentagons and heptagons.
It can be used to cage other molecules but forming around atoms or molecules and trapping them inside. So it can be used for drug delivery by caging the drug and taking it to where it is supposed to be. This is because it is absorbed better by the body.
Buckminsterfullerene was the first fullerene to be discovered

Question 20

What are nanotubes?

Answer 20

Fullerness can form nanotubes, tiny carbon cylinders.
The ratio between the length and diameter of nanotubes is very high
They can conduct electricity and thermal energy.
They have high tensile strength (can be stretched)

Question 21

What is nanotechnology?

Answer 21

Technology that uses very small particles called nanoparticles

Question 22

What are the uses of nanotubes?

Answer 22

Nanotubes can be used in electronics or to strengthen materials without adding much weight EG tennis racket frames

Question 23

What is metallic bonding?

Answer 23

The force of electrostatic attraction between positive metal ions and negative electrons which are in a regular structure.
Metallic bonding is very strong.

Substances that are held together by metallic bonding include elements and alloys.

Question 24

Why are metals solid at room temperature?

Answer 24

The electrostatic forces between the atoms and delocalised electrons are very strong so they need a lot of energy to be broken. This means it has a high boiling and melting point so it is solid at room temperature

Question 25

Why are metals good conductors of electricity and heat?

Answer 25

Because they have delocalised electrons so they are free to move and carry electric current and thermal energy through the whole structure

Question 26

Why are metals malleable ?

Answer 26

Because the layers can slide over each other so they can be bent or rolled

Question 27

What are alloys?

Answer 27

Alloys are a mixture of 2 or more metals or a metal and another element.
Alloys are needed because pure metals are too soft, so the pure metals are mixed with other metals to make them harder.
The new metal distorts the layers so they can slide over each other therefore alloys are harder

Question 28

Describe solid, liquids and gases

Answer 28

Solids= very strong forces in fixed positions- regular lattice arrangement.in a definite shape and volume.
Liquids= weaker attraction free to move past each other, not definite shape, random motion
Gas= very weak attraction, free to move, random motion, pressure can increase, not definite shape

Question 29

What are nano particles?

Answer 29

Nanoparticles are every tiny.
They have a large surface area to volume ratio this means that it’s SA is very large in relation to its volume.
As particles decrease in size it’s SA to V ratio increases.

Question 30

What are the uses of nano particles?

Answer 30

Drug delivery- easily absorbed by the body
Sun creams- can protect against UV rays
Moisturisers
Anitbacterial products- surgical masks, medical dressings
Help to make new catalysts