2.2.2 Bonding and structure Flashcards
Blurt everything you know about 2 electron pairs.
Blurt everything you know about 3 electron pairs.
Blurt everything you know about 4 electron pairs.
Blurt everything you know about 5 electron pairs.
Blurt everything you know about 6 electron pairs.
How to work out the formula of an ionic compound.
Swap and drop meth
Blurt everything you know about ionic compounds
- When negatively and positively charged ions bond (ionic bonding).
- Most ionic compounds dissolve in water as they are polar and can attract + or - ions and break up the structure.
- Conducts electricity when in molten or dissolved in solution as ions are free to move around
- High melting points
as there are strong electrostatic forces between oppositely charged ions. So lots of energy required to break these forces.
Blurt everything you know about covalent bonds give an example like ammonium.
- Sharing of outer electrons in order to obtain a full shell.
- Dative cov - One atom donates 2 electrons.
Draw the ionic bonding between Cl and Na,
Na and O
Mg and Cl
Al and F
(you may need more than one of an element for the ionic bonds). - easy
What and how becomes : polar molecule, and blurt everything you know about polar molecules, give examples
- A big difference in electronegativity, makes the bond more polar.
- As the charges don’t cancel out it is non-symmetrical
What happens when there’s a big difference in electronegativity
- The compound will become more ionic.
How does a dipole-dipole get induced.
- An induced dipole to dipole force occurs when a molecule is near another molecule. e.g bromine near ethene. in electrophilic addition. The ethene attracts on bromine and the electrons on the cov bond moves towards the second bromine.
Draw the bonding in O2 and N2
Hard : CO3 figure out the bonding and name the charge and OH?
The left-hand and bottom Oxygen atoms donate one dot each to form a single bond with the Carbon.
This leaves these two Oxygen atoms short of an electron each - this lack is made right by gaining two extra electrons (empty dots) and this is why it is CO32- rather than just CO3.
Draw CO2
What do we know about induced dipole to dipole forces, covalent bonds and a molecule
- Induced dipole-dipole forces holds the molecule together. Say induced dipole-dipole forces between molecules.
- Covalent bonds hold the 2 atoms together. Say covalent bonds between atoms in the exam
Fill in the gaps:
1. The ____ the molecule or atom, the _____ forces you have, as you have a _____ cloud.
2. When we boil a liquid we break ______ not _____
- The bigger the molecule or atom, the induced dipole-dipole forces you have, as you have a larger electron cloud.
- When we boil a liquid we break weak induced dipole-dipole forces not covalent bonds
Why do branched hydrocarbon bonds have lower boiling points and why do straight chain have higher boiling points.
- Longer = more induced dipole-dipole forces = more energy needed to overcome these forces = boiling point increase.
- Branched = can’t pack as closely together = less surface point of contact = weakness dipole-dipole forces = lower boiling point.
Which molecules contain a hydrogen bond ?
When a hydrogen atom is bonded to either a nitrogen, oxygen or fluorine atom
Draw a labelled diagram of the Hydrogen bonding in water 3 water molecules
Draw a labelled diagram of the Hydrogen bonding in ammonia & ammonia
Draw a labelled diagram of the Hydrogen bonding in ethanol & ethanol
Draw a labelled diagram of the Hydrogen bonding in ethanol & water
Links between polar covalent bond, polarisation and electronegativity
What’s the difference between intermolecular and intramolecular forces ?
- Intramolecular - Forces Inside the molecule e.g covenant and ionic (they are stronger)
- Intermolecular - Forces betweenmolecules e.g London forces, dipole-dipole
Intermolecular forces
Affects boiling point
Link
What are the three types of intermolecular forces caused by ?
