| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
| Is bond making exothermic or endothermic? | Exothermic (energy is released.) |
| What is ionic bonding | The strong electrostatic attraction between oppositely charged ions |
| What is a covalent bond? | - A bond formed by a shared pair of electrons between nuclei.
- Electrostatic attraction between the positive nuclei of the bonded atoms and the
negative electrons between these nuclei holds the atoms together |
| What is a dative covalent bond? | A covalent bond whereby both electrons in the shared pair are donated by one of the bonding atoms only |
| What is a sigma bond? | - The strongest type of covalent bond.
- Formed from the head-on overlap of orbitals |
| What is a pie bond? | - Weaker than a pie bond
- Formed from the sideways overlap of orbitals
- A carbon-carbon pie bond is formed from the sideways overlap of p-orbitals above
and below the plane of the carbon atoms |
| What is electron repulsion theory? | - Electron pairs repel each other meaning they position themselves as far as possible
- All bonding electron pairs repel each other equally
- Lone pairs offer more repulsion than bonded pairs |
| What is the shape and bond angle of a molecule with 2 bonding pairs? | Linear, 180*
e.g. Carbon dioxide, CO2 |
| What is the shape and bonding angle of a molecule with 3 bonding pairs? | Trigonal planar, 120*
e.g. Boron trifluoride, BF 3 |
| What is the shape and bonding angle of a molecule with 4 bonding pairs? | Tetrahedral, 109.5
e.g. Methane, CH4 |
| What is the shape and bond angle of a molecule 5 bonding pairs? | Trigonal bipyramidal, 90* and 120*
e.g. Phosphorus pentafluoride, PF5 |
| What is the shape and bond angles of a molecule with 6 bonding pairs? | Octahedral, 90*
e.g. Sulfur hexafluoride, SF6 |
| What is the shape and bond angle of a molecule with 2 bonding pairs and 2 lone pairs? | Non-linear/ bent, 104.5*
e.g. Water, H2O |
| What is the shape and bond angle of a molecule with 3 bonding pairs and 1 lone pair? | Pyramidal, 107* |
| What is electronegativity? | The ability of an atom to attract the bonding pair of electrons in a covalent bond. |
| What is hydrogen bonding? | - Strongest type of intermolecular force
- Type of permanent dipole-dipole interaction
- Occurs when hydrogen atom is bonded to a very electronegative atom (Nitrogen, oxygen or fluorine), which is close to another electronegative atom that has a lone pair of electrons |
| What is bond energy? | The measure of the strength of a chemical bond |
| What is bond length? | The average distance between the nuclei of two bonded atoms |
| What is bond polarity? | When 2 different atoms are joined by a covalent bond, the electronegativities of these atoms will be different ,meaning the electrons will be drawn towards the atom with greatest electronegativity. This atom will have a slightly negative charge charge while the other will be slightly positive. This charge difference is a dipole. If a bond is polar, it has a dipole. |
| Why can non-metal oxides undergo hydrolysis? | Oxygen is very electronegative.
As a result, a permanent dipole forms across the covalent bond and the atom that oxygen is bonded to become partially positive
When the oxide is added to water, lone pairs on oxygen in the water are attracted to the partially positive atom in the oxide causing hydrolysis. |
| How does the reactivity of a covalent bond depend on bond length | - As bond length increases, bond strength decreases.
- This is because there is less electrostatic attraction between the 2 nuclei and the shared pair of electrons between them.
- Reactivity increases |
| How does the reactivity of a covalent bond depend on bond strength? | The stronger the bond, the more difficult it is to break (requires more energy) and hence the less reactive the covalent bond. |
| How does the reactivity of a covalent bond depend on bond polarity? | The greater the bond polarity the more reactive the molecule |
| What is a permanent dipole and when does it occur? | A permanent dipole is a permanent difference in the partial charges of covalently bonded atoms
This occurs when there is a significant difference in electronegativities of the bonding atoms because the more electronegative atom has greater ability to attract the bonding pair of electrons meaning it has a slight negative charge. The other atom has a slight positive charge. |
| How do induced dipole-dipole interaction occur? | The random motion of electrons means that at any one point in time, there may be an uneven charge distribution. This causes an instantaneous dipole to be established between 2 atoms which can then induce dipole in neighbouring atoms / molecules |
| Why is bromine liquid at room temperature? | Although bromine only has London forces between molecules, Br2 molecules contain lots of electrons meaning these temporary dipoles are quite strong |
| Why can group 18 element become liquid despite the fact that they exist as single atoms? | - The random movement of electrons within the atoms means that temporary dipole within the atoms
- Temporary dipoles may induce dipoles in neighbouring atoms
- If the temperature is low enough, there will not be enough energy to overcome these weak London forces between the atoms meaning the gas will condense |
| Why does the boiling point of group 18 elements increase down the group? | The number of electrons and the atomic radius increases meaning that there are stronger temporary dipole and stronger London forces between the atoms. These stronger forces require more energy to overcome meaning a higher temperature is required to boil the liquid to turn it into a gas. |
| What is metallic bonding? | The electrostatic attraction between positive ions and delocalised electrons
A gaint metallic lattice is formed with the cations (positive ions) fixed in place |
| Why can metals conduct electricity ? | Metallic bonding means there are delocalised electrons that are free to move throughout the entire structure, allowing metals to conduct electricity. |
| Why do metals have a high melting point? | The strong electrostatic attraction between positive ions and delocalised electrons required a lot of energy to overcome to melt the substance. |
| Why are metals ductile and malleable? | The regular structure and delocalised electrons allow the layers of cations to slide over each other. |
| List some properties of giant covalent structures | - High melting/ boiling point - the net work of many strong covalent bonds requires a lot of energy to overcome
- Con not conduct electricity- no mobile charged particles
- Insoluble - the covalent lattice is too strong to be broken |
| List some properties of simple covalent structures. | - Low melting/boiling point - weak intermolecular forces (London forces) between molecules
- Can not conduct electricity - no mobile charges |
| List some properties of ionic compounds | - High melting / boiling points - strong electrostatic attraction between oppositely charged ions required a lot of energy to break
- Electrical conductor - when aqueous or molten, the ions are free to move and they can conduct electricity, when solid, the ions are fixed so no conductivity
- Soluble in polar solvents - charges parts of the solvent are attracted to the oppositely charged ions. |
| List the properties of molecules with hydrogen bonds between them. | - Higher than expected melting/ boiling points - hydrogen bonds are much stronger than London forces meaning more energy is needed to overcome them.
- Soluble in water - stronger permanent dipoles allow the formation of hydrogen bonds with water
- Non-conductores - no mobile charges so are unable to conduct electricity. |
| Is bond breaking endothermic or exothermic? | Endothermic (energy is taken in). |
| Is bond making exothermic or endothermic? | Exothermic (energy is released.) |
| Ionic compounds are solids at room temperature and pressure, because: | - Strong electrostatic forces (ionic bonds) holding the positive and negative ions together.
-Ions are regularly arranged in a lattice, with oppositely charged ions close to each other |
