What is a molecule?
Groups of atoms joined together by chemical bonds.
What were the 2 types of bonds mentioned in the lecture powerpoint?
Explain what a covalent bond is
A bond where two atoms share a pair of electrons between them.
Explain what an ionic bond is
An ionic bond is an electrostatic attraction between a positive ion and negative ion.
Name some VSEPR Theory molecule shapes
Trigonal planar, linear, bent, etc.
What is the VSEPR theory?
(Valence Shell Electron Pair Repulsion pronounced Ves-pur or ves-seh-per)
It is a theory in chemistry that allows scientists to predict the shape of molecules from determining the number of electron pairs of a molecule
What is the following notation called:
1s2 2s2 2p6 3s2 3p6 4s2
Point to the s-block, d-block, p-block and f-block elements in the following periodic table then check if you're correct:
Notice that helium is an s-block element.
What is an orbital?
An orbital is an area where an electron is most likely to be (90% of the time).
What shape is an s-orbital?
What shape is a p-orbital?
The three p-orbitals are ___________ shaped but are oriented ___________ to each other
Describe the shape and orientation of the five d-orbitals
- 4 of the 5 d-orbitals are shaped exactly the same but are orientated differently. These 4 d-orbitals all look like flowers with 4 petals.
- The fifth d-orbital has a different shape from the other 4. It looks like a donut that has been pushed into the middle of a dumbbell
How are sp3 hybrid orbitals made?
- First of all, in carbon, an electron from its 2s orbital gets promoted to the unoccupied p-orbital.
- Then the 2s-orbital mixes with the three 2p-orbitals to form four identical sp3 orbitals. This is why carbon can form four bonds.
Bases of DNA and RNA have a ______ shape.
Why do the bases of DNA and RNA have a planar (flat) structure?
Usually, molecules with N as their central atom adopt a trigonal pyramidal shape but in the case of the bases of DNA and RNA, the nitrogen atoms in the bases donate their lone pairs to the ring structure.
What is the difference between intermolecular forces and intramolecular forces?
Intermolecular bonds exist between molecules whereas intramolecular bonds are bonds that exist between atoms in a molecule.
Name all 4 intermolecular forces mentioned in lecture powerpoint and state another name that these intermolecular forces (bonds) can be collectively called.
- Dipole/Dipole forces (aka Keesom forces)
- Dipole/Induced Dipole (aka Debye forces
- Induced dipole/Induced dipole (aka London dispersion forces for Higher and Advanced Higher chemistry scum)
- Hydrogen bonds (technically they are dipole/dipole forces so there is technically only 3 intermolecular bonds)
What is a dipole?
A dipole is a separation between two equally but oppositely charged poles or particles. (a water molecule has two poles - a positive charge on the hydrogen pole (side) and a negative charge on the oxygen pole (side)).
Which intermolecular bond can explain why ammonia, water, and hydrogen fluoride have a higher boiling point than predicted?
Which three atoms must be attached to a hydrogen atom to facilitate hydrogen bonding?
N, O, and F
How strong is a hydrogen bond in comparison to a covalent bond?
A Hydrogen bond is one-tenth of the strength of a covalent bond.
Describe the structure of ice.
Each O atom is surrounded tetrahedrally by 4 other H atoms. 2 of these H atoms are covalently bonded to the O atom (a water molecule) and the other 2 are hydrogen bonded to the O atom.
You might like this video:
Ted video - why does ice float?
Which very important biomolecules depends on hydrogen bonds?
DNA and RNA
Why is hydrogen bonding so important in DNA?
- It stabilizes the structure of DNA
- It allows DNA to be duplicated
How many hydrogen bonds exist between A and T and G and C