Biomolecules - week one -Reading
- Created by: HamiltonElf
- Created on: 22-01-21 15:21
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Chemical bonds and molecules
- Two or more atoms bonded together make up a molecule.
- Two oxygwn atoms bind together to form a oxygen molecule
- O2 is called a molecular formula.
- Compound is a molecule that has diffrent elements.
- Compounds have emergent properties (diffrent to properties of elements that combined to form it)
Covalent bonds are formed when atoms share electrons to fill their outer shells
- A covalent bond is a chemical bond in which two atoms share a pair of electrons.
- Occur when outershells are not full.
- The octet rule states that many atoms are most stable when they have eight electrons in their outermost electron shell.
- A double bond occurs when atoms share two pairs of electrons rather than one pair.
Covalent bonds may be polar or nonpolar
- Some atoms attract shared electrons more strongly than do other atoms.
- Electronegatrivity of an atom measures how electrons bond with other atoms.
- Two atoms with diffrent electronegativities form a covalent bond, electrons are more likely to be closer to the nucleus of the atom of higher electronegativity than to the nucleus of the atom of lower electronegativity.
- Polar covalent bonds are when electrons around the nuclei causes a polarity across the molecule. E.G water.
Hydrogen bonds and van der waals dispersion forces promote interactions between and within molecules
- Polar covalent bonds with another moelcule through weak interaction called a hydrogen bond.
- Hydrogen bonds, like those between water moelcules are represented in diagrams by dashed or dotted lines to ditingusih them from covalent bonds.
- Another type of weak molecular attraction is due to van der Waals dispersion forces, electrons are located within orbitals in a random way.
Ionic bonds involve an attraction between positive and negative ions
- Atoms are electrically neutral because they contain equal nu,bers of negative electrons and positive protons.
- Ana tom or moelcule gains or loses one or more electrons, acquires a net electric charge and becomes an ion,
- Ions that have a net positive charge are called cations.
Molecules may change their shapes
- Molecules containing covalent bonds are not rigidm inflexible structures.
- Single covalent bond as an axle around which joined aroms can…
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