Bonding & Structure

Question 1

Why do atoms bond?

Answer 1

• They aim for greater stability and reduce energy in their structure
• Generally aim for full energy shells

Question 2

What are the types of bonds?

Answer 2

• They are all an electrostatic force of attraction between oppositely charged species
• The three types are
  Ionic: involves gain or loss of electrons to form ions.
  Covalent: involves sharing of electoons
  Metallic: involves loss of electrons

Question 3

Tell me about ionic bonds.

Answer 3

• Ionic bonds form through the electrostatic force of attraction between oppositely charged ions
• Atoms become stable by gaining or losing electrons to get full shells

Question 4

What are cations and anions?

Answer 4

Cations: have a positive charge and have lost electrons

Anions: have a negative charge and have gained electrons

Question 5

What are the properties of ionic compounds?

Answer 5

• All have an overall charge of 0
• High melting & boiling point: because there are billions of ions attracted so a lot of energy is needed to overcome the ionic bonding
• When solid does not conduct electricity: because the ions are not free to move
• Ionic substances are soluble in water: because water is a polar solvent that disrupts the ion
• Conducts electricity when dissolved in water or molten: because the ions are free to move

Question 6

Tell me about covalent bonding.

Answer 6

• Mostly between non-metals
• Made through the sharing of electrons
• If atom needs one electron, it must share one of its own

Question 7

What are the properties of covalent substances?

Answer 7

• Low melting & boiling points: breaking the attractive forces of molecules is easy
• Do not conduct electricity as the atoms are neutral and there are no mobile ions or electrons to pass the charge
• Most do not dissolve in water

Question 8

How do metallic bonds work?

Answer 8

• In metals, atoms are tightly packed together and form a regular lattice
• Tight packing allows outermost electrons to separate from atoms
• Results in lattice of ions in a sea of electrons
• Ions have regular pattern so metals are crystalline
• Released electrons cause atoms to have a positive charge
• Metallic bonding is the electrostatic force of attraction between positive metal ions with sea of electrons
• Structure of metals greatyly impact density, conductivity, malleability, and melting and boiling points

Question 9

What causes metals to be malleable?

Answer 9

They have layers so if a metal atom gets moved, it moves to the next layer

Question 10

What is an alloy?

Answer 10

Metals made by combining 2 or more metals.

Question 11

Define simple covalents and giant molecular structures.

Answer 11

• Simple covalents have a formula
• Giant molecular structures: sometimes millions of atoms joined together produce a giant lattice and don’t have a chemical formula

Question 12

Tell me about graphite

Answer 12

• Giant covalent
• 3 covalent bonds per carbon atom
• High melting and boiling point due to strong covalent bonds
• Conductor due to delocalised electrons
• Soft and brittle

Question 13

Tell me about diamond

Answer 13

• Giant covalent
• 4 covalent bonds per c atom
• High melting and boiling point due to strong covalent bonds
• Insulator due to no delocalised electrons
• Very hard and strong

Question 14

Tell me about graphene

Answer 14

• Giant covalent
• 3 covalent bonds per carbon atom
• Very high melting and boiling point due to strong covalent bonds
• Conductor due to delocalised electrons
• Very strong

Question 15

Tell me about buckminsterfullerene

Answer 15

• Simple molecular
• C 60
• Strong covalent bonds
• 3 covalent bonds per carbon atom
• Low melting and boiling point due to weak intermolecular forces
• Insulator because electron movement is inhibited
• Soft and brittle