Forces between molecules Flashcards
What types of bonds hold atoms in molecules and in giant structures
Atoms in molecules and in giant structures are held together by strong covalent, ionic or metallic bonds
How many types of intermolecular forces are there? What are the names of all the intermolecular forces?
There are three intermolecular forces;
1) van der Waals
2) dipole - dipole forces
3) hydrogen bonds
If intermolecular forces are strong enough between molecules, what can be formed?
If intermolecular forces are strong enough, then molecules that are held closely together enough will become lipids or even solids
What do van der Waal forces act between?
What do dipole - dipole forces act between?
What do hydrogen bonds act between?
van der Waals act between all atoms and molecules
dipole - dipole forces act only between certain types of molecules
hydrogen bonds act only between certain type of molecules
What forces hold together molecules and separate atoms?
Molecules and separate atoms are attracted to one another by other weaker forces, called intermolecular forces
What is the rank order of strength between van der Waals, dipole - dipole forces and hydrogen bonds?
1) van der Waals - weakest
2) dipole - dipole forces - medium
3) hydrogen bonds - strongest
If a molecule has more than one polar bond, what occurs commonly? If a molecule has more than one polar bond what main also occur depending on the shape of the molecule?
If a molecule has more than one polar bond there may not be a dipole moment, as the effect of each bond may cancel.
If a molecule has more than one polar bond, the effects may add up and reinforce each other, but this depends on the shape of the molecule
What type of forces act between molecules that have permanent dipoles?
Dipole - dipole forces act between molecules that have permanent dipoles
When two polar molecules have dipoles, what occurs?
Two polar molecules that both have dipoles will attract one another. No matter their starting positions, molecules with dipoles will ‘flip’ to make an arrangement where the two molecules attract
What are van der Waals?
van der Waals are a result of positive and negative charges which produce very weak electrostatic attractions between all atoms and molecules
What types of molecules and atoms do van der Waals occur in?
All atoms and molecules have van der Waal forces
How do van der Waals work?
The distribution of charge is constantly changing in atoms. Any arrangement within an atom will result in a temporary dipole. This dipole would then affect the electron distribution in nearby atoms as they are attracted to the atom in the particular temporary lobe
What is a temporary dipole?
A temporary dipole occurs when an arrangement is formed within an atom resulting in a dipole, temporary dipoles are dipoles that happen just for an instance
Describe what happens as the electron distribution of the original atom changes
As the electron distribution of the original atom changes, atoms around it will be induced to form dipoles, that will be attracted to the original atom
What is the cause of a dipole?
Dipoles are caused by the changing positions of the electron cloud
