Water chemistry Flashcards
Describe electronegativity as it is represented in the periodic table.
Electronegativity increases from left to right, and from bottom to top.
what is the concept of polarity in water?
Oxygen is partially negative, whereas hydrogen is partially positive. Hydrogen electrons are pulled towards the Oxygen.
State the meaning of dipole.
A bond with a positive and negative end.
What is the geometry of a water molecule.
The angle is 104.3 degrees
The covalent bond length is 0.095 nm
The Van der Waals radiuses of Oxygen and Hydrogen are 0.14 nm and 0.12 nm respectively.
What determines solvency?
Polarity
Describe ionic and polar compounds respectively.
Ionic compounds have full charges.
Polar charges have partial charges.
What influences electrostatic attraction?
Unlike charges
How does salt dissolve in water?
The negative oxygen ends of water molecules attract the positive sodium ions.
The positive hydrogen ends of water molecules attract the negative chloride ions.
These forces of attraction pull the ions apart.
How does sugar dissolve in water?
Forces of attraction between the negative and positive ends of water and sugar molecules pull individual sugar molecules away from the sugar crystal. Little by little the sugar molecules are separated from the crystal and surrounded by water.
Explain hydrogen bonds.
Interaction between H bound to electronegative atom with a neighboring electronegative atom.
Hydrogen bond donor and Hydrogen bond acceptor
Adhesiveness, Cohesiveness, Temperature Retention
In ice – Lattice form
Explain Amphipathic molecules
They are called micelles (based on their shape)
They have a hydrophilic head (water loving) and hydrophobic (water hating tail)
Describe the individual structure of an amphipathic molecule.
The hydrophilic head faces outward and contains phosphate and glycerol.
The hydrophobic tail faces inward and contains two tails (strands) with saturated and unsaturated fatty acids.
*The bent one is unsaturated as it has a double bond
*The straight one is saturated as it only contains single bonds.
Hydrophobic interactions
Hydrophobic have a polar head and a non polar tail.
State and explain the types of hydrogen bonding in proteins.
Interstrand bonding: hydrogen bonds bonding different strands. eg DNA double helix
Intrastrand bonding: hydrogen bonds bonding the same strand.
Which substances dissolve in water.
Polar substance tend to dissolve in water, the opposite is true for non polar.
