Topic 1 - Ionic bonding Flashcards
What is an ionic bond?
A bond between a metal and non-metal involving the transfer of electrons.
In terms of electrons, describe what happens to the metal and non-metal when an ionic bond forms
- The metal atom loses electrons to become a positively charged ion (cation).
- The non-metal gains electrons to become a negatively charged ion (anion).
What is an ion?
An ion is an atom or group of atoms with a positive or negative charge.
If an ion is positively charged, has it lost or gained electrons?
- It has lost electrons.
- There are fewer negatively charged electrons to cancel out the charge of the positive protons.
- This means the overall charge becomes positive.
Na+ has the atomic number 11 and the mass number 23. How many protons, neutrons and electrons are in this ion?
- Protons: 11
- Electrons: 10
- Neutrons: 12
O2- has the atomic number 8 and the mass number 16. How many protons, neutrons and electrons are in this ion?
- Protons: 8
- Electrons: 10
- Neutrons: 8
Why do elements in groups 1, 2, 6 and 7 readily form ions?
So they become more stable and achieve the electron structure of the noble gases (group 8).
What type of ions do elements in group 1 and 2 form?
Cations (positive)
- Group 1 metals will form 1+ ions
- Group 2 metals will form 2+ ions
What type of ions do elements in groups 6 and 7 form?
They are non-metals so form anions (negative)
- Group 6 wil form 2- ions
- Group 7 will form 1- ions
What does it mean if an ionic compound ends in -ide?
The compound contains 2 elements.
What does it mean if an ionic compound ends in -ate?
The compound contains at least three elements, one of which is oxygen.
Describe the structure of an ionic compound
- Lattice structure.
- Regular arrangement of ions.
- Ions held together by strong electrostatic forces between ions with opposite charges.
What is the chemical formula of sodium oxide, formed from Na+ and O2-?
- Na2O
- Charges must balance so 2 sodium ions are required
What is the chemical formula of magnesium hydroxide, formed from Mg2+ and OH-?
- Mg(OH)2
- Charges must balance so 2 hydroxide ions are required.
What is a covalent bond?
A bond formed when an electron pair is shared between two atoms.
What forms as a result of covalent bonding?
A molecule
Draw a dot and cross diagram for the formation of methane (CH4)
True or false? ‘Covalent bonds are weak’
- FALSE
- Covalent bonds are strong
Which is smaller, an atom or a molecule?
- An atom.
- Simple molecules consist of atoms joined by strong covalent bonds within the molecule.
Why do ionic compounds have high melting points?
Strong electrostatic attraction between the positive and negative ions requires a lot of energy to overcome.
When do ionic compounds electricity? Why?
When molten or aqueous (dissolved in water) because the ions are charged and free to move. When solid, the ions are fixed in an ionic lattice so can’t move.
Why do simple molecular compounds have low melting and boiling points?
They have weak intermolecular forces (forces between molecules) which only require a little energy to overcome.
Do simple molecular compounds conduct electricity? Why / why not?
No because there are no charged particles.
Do giant covalent structures have a high melting point? Explain your answer.
Yes because they have lots of strong covalent bonds which require a lot of energy to break
How do metals conduct electricity and heat?
- The positive ions are fixed in a sea of delocalised electrons.
- These electrons are free to move and carry charge / energy.
True or false? ‘Metals are insoluble in water’
- cTRUE
Name two giant covalent structures formed from carbon atoms
- Graphite
- Diamond
Describe the structure and properties relating to graphite
- Each carbon atom bonded to 3 other carbon atoms.
- Layers of hexagonal rings of carbon atoms.
- Weak intermolecular forces between layers.
- One delocalised electron per carbon atom.
Describe and explain the properties of graphite
- Graphite is soft / slippery because there are only weak intermolecular forces between layers which allow the layers to slide over one another.
- Graphite conducts electricity because there is one delocalised electron per carbon atom. The delocalised electrons are mobile charges.
Describe the structure of diamond
- All carbon atom are covalently bonded to four other carbon atoms.
- No delocalised electrons
Describe the properties of diamond
- Very hard.
- Very high melting point.
- Doesn’t conduct electricity as there are no charged particles.
What are the uses of graphite? Why?
- Electrodes because graphite conducts electricity and has a high melting point.
- Lubricant because it’s slippery (the layers in graphite can slide over each other).
Why is diamond used in cutting tools?
It’s very hard
What is a fullerene?
A fullerene is a molecule made of carbon, shaped like a closed tube or hollow ball.
Name two fullerenes
- Graphene
- C60 (buckminsterfullerene)
What are the properties of the fullerene C60?
- Slippery due to weak intermolecular forces.
- Low melting point.
- Spherical.
- Strong covalent bonds between carbon atoms in a molecule.
- Large surface area.
What are the properties of graphene?
- High melting point due to covalent bonding between carbon atoms.
- Conducts electricity because it has delocalised electrons.
Why is graphene useful in electronics?
- It is extremely strong and has delocalised electrons which are free to move and carry charge.
- It is only one atom thick as it is a single layer of graphite.
