What is a molecule?
A group of atoms joined together by chemical bondings
What are the two different types of chemical bondings?
1-Ionic bond 2-Covalent bond
Explain what a covalent bond is:
Sharing of a pair of electrons between two atoms
Explain what an ionic bond is:
Complete transfer of one or more electrons from one atom to another.
If a molecule is hybridized sp which shape has it got?
Linear (Angle 180°)
If a molecule is hybridized sp2 which shape has it got?
Trigonal planar (Angle 120°)
If a molecule is angular what sort of hybridization has it got?
If a molecule is hybridized dsp3 which shape has it got?
If a molecule is tetrahedral what sort of hybridization has it got?
If a molecule is hybridized d2sp3 which shape has it got?
What is the hybridization of CH4, NH3 and H20?
What is the hybridization of ATP?
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 shape is an s-orbital?
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. The fifth d-orbital has a different shape from the other 4.
A change in the shape of atomic orbitals which allows electron to occupy new locations. The results is an hybrid orbital.
How are sp3 hybrid orbitals made?
1-First of all, in carbon, an electron from its 2s orbital gets promoted to the unoccupied p-orbital. 2-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.
Intermolecular forces are ____ than intramolecular forces
What are the three types of non-covalent forces (Van der Waals forces)?
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)
What is a dipole?
A dipole is a separation between two equally but oppositely charged poles or particles.
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
Describe induced dipole-induced dipole forces:
Weak molecular interactions that occurs between all molecules.
What are the three features of induced dipole-induced dipole forces?
1- They are short lived 2- They are weak 3- They operate over short distances
What are the two factors that affect induced dipole-induced dipole forces?
Size (bigger molecules have stronger dipoles because they have more electrons) and shape (Long and thin molecules develop stronger dipoles because the lie more closely).
Describe dipole-dipole forces:
The forces that exist between opposite charges on polar molecules (the are permanent).
Which very important biomolecules depends on hydrogen bonds?
DNA and RNA.
Why is hydrogen bonding so important in DNA?
1-It stabilizes the structure of DNA 2-It allows DNA to be duplicated
How many hydrogen bonds exist between A and T and G and C?
A and T - 2 H. bonds G and C - 3 H. bonds
What is an hydrogen bond?
A dipole-dipole interaction between an hydrogen and an electronegative atom of N, O or F.
What are the two conditions for hydrogen bonds?
1- The hydrogen atom must be bonded to an atom of N, O or F. 2- The hydrogen bond can only be formed between the hydrogen atom and a lone pair of an atom of N, O or F.