Bonding

Question 1

What is ionic bonding?

Answer 1

• in ionic bonding, atoms lose or gain electrons to form charged particles called ions, which are then strongly attracted to one another (because of the attraction of opposite charges).
• this strong attraction is known as electrostatic attraction: it gives ionic compounds their high melting and boiling points

Question 2

What is oxidation?

Answer 2

• when an atom loses electrons

Question 3

What is reduction?

Answer 3

• when an atom gains electrons

Question 4

Which groups of elements most readily form ions and why?

Answer 4

• groups 1, 2, 6 and 7

- their shells are nearly full or only have 1 or 2 electrons in the outer shell

Question 5

What are cations and which groups of elements become them?

Answer 5

• positively charged ions

- groups 1 and 2 as they lose electrons

Question 6

What are anions and which groups of elements become them?

Answer 6

• negatively charged ions

- groups 6 and 7 as they gain electrons

Question 7

What happens when the cations collide with the anions?

Answer 7

• they attract each other to form an ionic compound

Question 8

Why can only elements of opposites sides of the periodic table form ionic compounds?

Answer 8

• because one of them becomes a cation and the other an anion
• therefore, it’s between a metal and non-metal

Question 9

What do compounds with ionic bonding always have?

Answer 9

• giant ionic structures

Question 10

What is the structure of giant ionic structures?

Answer 10

• ions are held together in a closely packed 3D lattice arrangement by the attraction between oppositely charged ions

Question 11

Describe the electrostatic attraction between the oppositely charged ions

Answer 11

• very strong

Question 12

What are the properties of ionic compounds?

Answer 12

• high melting and boiling point
• brittle
• conduct electricity when molten or in solution, but not as a solid

Question 13

Why do ionic compounds have high melting and boiling points?

Answer 13

• a lot of energy is needed to overcome the strong electrostatic attraction.

Question 14

Why are ionic compounds brittle?

Answer 14

• if you hit it, ions of the charge move to become adjacent to each other
• so they repel

Question 15

Why do ionic compounds only conduct electricity when molten or in solution?

Answer 15

• in a solid, ions are held in a lattice, so are not free to move
• in molten or solution, ions are free to move

Question 16

How do the charges on the ions in the lattice affect the strength of the ionic bonding?

Answer 16

• the higher charge ions are held together by stronger forces of attraction
• they will also have higher melting and boiling points

Question 17

How do you draw a diagram to represent the positions of ions in sodium chloride?

Answer 17

• draw one now

Question 18

What is a covalent bond?

Answer 18

• atoms share a pair of electrons with other atoms to make full outer shell

Question 19

What is the strength of attraction between the shared electrons and the nuclei in covalent bonding?

Answer 19

• a strong attraction

Question 20

What are simple molecular/covalent substances?

Answer 20

• the atoms within a molecule are held together by very strong covalent bond
• talk about molecules!!
• however, the forces of attraction between the molecules (intermolecular forces) are very weak

Question 21

What is the result of weak intermolecular forces?

Answer 21

• very low melting and boiling points

- the molecules are easily parted from each other

Question 22

What are the properties of simple covalent substances?

Answer 22

• low melting/boiling point

- do not conduct electricity: there are no delocalised electrons or ions

Question 23

What are giant covalent structures?

Answer 23

• a lattice of atoms that are joined by covalent bonds
• talk about atoms!! not ions or molecules
• all atoms are bonded to each other by strong covalent bonds

Question 24

What are the properties of giant covalent structures?

Answer 24

• really high melting and boiling points: it takes a lot of energy to break them
• do not conduct electricity: except graphite
• usually insoluble in water

Question 25

Give 3 examples of giant covalent structures

Answer 25

- diamond - graphite - silicon dioxide

Question 26

Draw and describe diamonds

Answer 26

- each carbon atom forms forms four covalent bonds in a very rigid giant covalent structure - very high melting point - does not conduct electricity - very hard because atoms cannot be broken. you would have to break very strong covalent bonds. used for cutting tools

Question 27

Draw and describe graphite

Answer 27

- each carbon atom forms three covalent bonds, creating layers which are free to slide over each other - strong covalent bonds within each layer - conducts electricity: delocalised electrons between layers - soft and flaky: layers of C atoms can slide over each other - very high melting point - used as lubricant, soft and slippery

Question 28

What are giant metallic structures?

Answer 28

- a giant structure of positive ions surrounded by a sea of delocalised electrons - the attraction between the positive ions and the electrons is called metallic bonding

Question 29

Draw a metallic lattice

Answer 29

- have a lattice of cations, at least 3 x 3 | - sea of delocalised electrons

Question 30

What are the properties of giant metallic structures?

Answer 30

- conductors of electricity and heat as solid and liquid: delocalised electrons are free to move - malleable: layers of cations can slide over each other, - high melting point( not as high as ionic): strong electrostatic attraction between cations and delocalised electrons, so lots of energy to overcome it