Questions: The Chemical Context Of Life

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Unit 1 Objectives chapters 2-5
The Chemical Context of Life – Chapter 2
I) Bonding – Know the 3 major types of bonding and how the atoms change or properties change during each.
The 3 bonds are: Covalent, Ionic and hydrogen bonds.

A) Explain Ionic Bonds and ionization
Ionic bonds, bond through electrostatic force. Where one ion has too many ions and the other has to few.
Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons.

B) Explain Covalent Bonds
Covalent bonds, bond by the sharing of electrons usually between two non-metals

What does it mean to be polar or non-polar
Polar shares electrons unequally and non-polar share equally

How are bonds signified when diagramed? – single vs. double bond A double covalent bond is where two pairs of electrons are shared between the atoms rather than just one pair.

What is a hydrogen bond?
Hydrogen bonds, bond when it’s attracted to an electronegative atom usually with either nitrogen, oxygen or fluorine.

Name 3 significant factors of hydrogen bonding in organisms.
3 factors:
1. concentrations. 2. electronegative of the element. 3. number of hydrogen atoms present in the compound. 4. size of the compound undergoing hydrogen bonding.
Water and Life – Chapter 3
I) Water – Explain how the polarity and hydrogen bonds of water causes the water properties and solution of life
A) Explain the water properties
Temperature – Stabilizing (heat reservoir, evaporation)
Temperature: the degree or intensity of heat present in a substance or object, esp. as expressed according to a comparative scale and shown by a thermometer or perceived by touch
Heat reservoir: a hypothetical body of infinitely large mass capable of absorbing or rejecting unlimited quantities of heat without undergoing appreciable changes in temperature, pressure, or density.
Evaporation: matter or the quantity of matter evaporated or passed off in vapor

(A.1.a) What types of molecules can and cannot be dissolved by water?
(A.1.b) Nonpolar molecules cannot dissolve in water. Like oil.
A.2) Cohesion (surface tension and capillary action)
The molecular force between particles within a body or substance that acts to unite them.
A.3) Adhesion (capillary action) The molecular force of attraction in the area of contact between unlike bodies that acts to hold them together. Expansion: the act or process of expanding

Explain how water is the solvent of life
Water serves to suspend the red blood cells to carry oxygen to the cells. It is the solvent for the electrolytes and nutrients needed by the cells, and also the solvent to carry waste material away from the cells.
Describe an aqueous solution
A solution in which the solvent is water. Explain how ions and water form a hydration shell. When an ion is inserted into a water configuration, it changes the structure of the hydrogen bond network. A water molecule tends to rotate (reorient) so that its polarized charge concentration faces the opposite charge of the ion. As the water molecules orient themselves towards the ion, they break the hydrogen bonds to their nearest neighbors How do polar molecules become dissolved in water? like dissolves like, so polar compounds will dissolve in water (which is polar) Explain how hydrophilic and hydrophobic properties impact solubility. Hydrophilic: Having an affinity for water; readily absorbing or dissolving in water. Hydrophobic: having little or no affinity for water. Explain how to make a 1 molar solution of NaCl. 1 molar means 1 mole / 1 L of solution

Mass of 1 mole of NaCl = 58.44 g/mol

You make this solution adding 58.44 g plus enough water to reach the volume of 1 L

II) Acid / Base – How much does each unit on the pH scale represent?
An acid is a substance that donates hydrogen ions. Because of this, when an acid is dissolved in water, the balance between