CC5- Ionic Bonding, CC6- Covalent Bonding, CC7- Types Of Substances

Question 1

What are ions?

Answer 1

• Ions are charged particles which have either lost or gained electrons
• ions aim to get a full outer shell (gain a stable, electronic structure)
• When an atom gains electrons, a negative ion (anion) is formed
• when an atom loses electrons, a positive ion (cation) is formed
• for example, if 2 electrons are lost, the charge will be 2+, if 3 electrons are gained the charge is 3-
• all ions in the same group will have the same number of outer electrons on the outer shell so they will have to lose or gain the same number of electrons In order to get this full outer shell. Therefore they will form ions with the same charges. 

Question 2

What is ionic bonding?

Answer 2

• ionic bonding is when a metal and a nonmetal react together, and the metal atom loses electrons to form a positive ion (cation), and a nonmetal gains these electrons to form a negative ion (anion)
• these oppositely charged ions are strongly attracted to each other by electrostatic forces
• this is an ionic bond

Question 3

What are the structures of ionic compounds like?

Answer 3

• Ionic compounds, always have a giant ionic lattice
• since they are held together by strong electrostatic forces of attraction between oppositely charged ions, this forms strong ionic bonds in all directions that allow the ions to be packed together in a regular, repeating arrangement (lattice)

Question 4

How do dot and cross diagrams show how ionic compounds are formed?

Answer 4

• dot and cross diagram is show how electrons leave the outer shell of a metal and are gained by the outer shell of the nonmetal

Question 5

What are the properties of ionic compounds?

Answer 5

• Ionic compounds have high, melting and boiling points due to the strong attraction between the ions, it’s takes a large amount of energy to overcome this attraction
• Solid ionic compounds, don’t conduct electricity, because the ions are fixed in place and can’t move
• When an ionic compound is in an aqueous solution, however, the ions are free to move and can carry an electric charge
• many ionic compounds also dissolve easily in water, so the ion separate and are able to move freely in a solution and carry an electric charge

Question 6

What are the disadvantages of 2-D representations of molecules?

Answer 6

• While they are simple and show how atoms are connected, they don’t show the shape of the substance and they don’t give you an idea about the sizes of the atoms

Question 7

What are the disadvantages of dot and cross diagrams?

Answer 7

• While they show how compounds and molecules are formed, and where the electrons in the bonds or ions came from, they don’t show you anything about the size of the atoms or how they are arranged

Question 8

What are some disadvantages of 3-D models?

Answer 8

• 3-D ball and stick models show which atoms are joined together. However, they also show the atoms too far apart and it is also unrealistic because there are not sticks holding the atoms together.
• They also do not show the correct scales

Question 9

What are covalent bonds?

Answer 9

• covalent bonds are formed between nonmetal atoms and are produced by sharing a pair of electrons
• By forming this bond, the atoms become more stable because they can use the shared electron to both complete the outer electron shells
• within single covalent bonds, they only share a single pair of electrons however, in a double bond, they can share more than one pair of electrons
• substances that contain covalent bonds, usually have simple molecular structures

Question 10

What are the properties of simple molecular structures?

Answer 10

• The atoms within the molecule, are had held together by very strong covalent bonds However, the forces of attraction between these molecules are very weak (they have weak intermolecular forces)
• They often have low, melting and boiling points, because there are weak, intermolecular forces, you only have to overcome the weak intermolecular forces, and not the covalent bonds
• mostly gases or liquids at room temperature
• they do not conduct electricity, because they don’t contain any three electrons or ions

Question 11

What are polymers?

Answer 11

• polymers are molecules made up of a long chains of covalently bonded carbon atoms
• Carbon atoms can form up to 4 covalent bonds with other atoms

Question 12

What are the properties of giant covalent structures?

Answer 12

• In giant covalent structures, all the atoms are bonded to each other by strong covalent bonds
• They have very high melting and boiling points as lots of energy is needed to break a covalent bonds
• They don’t contain charged particles so they don’t conduct electricity
• They are not soluble in water

Question 13

What are four carbon-based structures?

Answer 13

• Diamond
• Graphite
• graphene
• fullerenes

Question 14

Describe the giant covalent structure of diamond and its uses

Answer 14

• Diamond is made up of a network of carbon atoms that each form 4 covalent bonds
• The strong covalent bonds take lots of energy to break so diamond has a high melting point
• The strong covalent bond holds the atoms in a lattice structure, making the diamond really hard
• because it is very hard, it is used to cut things
• it also does not conduct electricity because it has no free electrons or ions therefore can be used as an electrical insulator

Question 15

Describe the giant covalent structure of graphite and its uses.

Answer 15

• In graphite, each carbon atom, only forms, three covalent bonds
• graphite is sheets of carbon atoms arranged in hexagons
• There are not any covalent bonds between the layers that only held together weekly, so they’re free to move over and slide past each other
• This causes graphite to be soft and slippery, so it is ideal as a lubricating material
• Graphite have a high melting points since covalent bonds in the layers need lots of energy to break, however, between the layers there are weak forces
• carbon has four outer electrons that are used in bonds. However, graphite only uses three out of this for this means that graphite will have delocalised electrons that are free to move, and therefore able to conduct electricity
• since it conducts, electricity well and is cheap and not very reactive. It is used as electrodes in electrolysis

Question 16

Describe the giant covalent structure of graphene.

Answer 16

• graphene is one layer of graphite
• It is a sheet of carbon atoms join together in hexagons connecting to 3 other atoms
• It’s covalent bonds, make it very strong and it also allows free delocalised electrons to move across its surface therefore making it a good electrical conductor

Question 17

Describe the structure of fullerenes.

Answer 17

• fullerenes is a simple molecules of carbon in which each carbon atom is covalently bonded to 3 other carbon atom
• It has low melting points, due to weak intermolecular forces between molecules, these weak forces also make them soft and slippery. However, the molecules themselves are very strong due to their covalent bonding.

Question 18

Describe metallic bonding?

Answer 18

• in a metal atom, it will lose electrons in order to gain a full outer shell. This causes there to be positive metal ions.
• This means that the electrons that were once in the outer shell become delocalised and free to move around
• There will be electrostatic attraction between positive metal ions and a negative delocalised electrons
• Metallic bonding is very strong due to this attraction 

Question 19

What are the physical properties of metals?

Answer 19

• The electrostatic forces between the metal ions, and the delocalised sea of electrons are very strong so lots of energy is needed to overcome this
• This means that compounds with metallic bonds (metals) will have very high melting and boiling points
• metals are dense as the ions in the metallic structure are packed closely together in their lattice
• The layers of atoms in a metal are able to slide over each other, making metals malleable
• The delocalised electrons carry electrical charge as well as thermal heat through the material so metals are good conductors of electricity and heat