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The characteristics of the molecules of water in chemistry

Other planets have water, but they either have it as a gas Venus or ice Mars. This relationship is shown in Figure 1. Recent studies of Mars reveal the presence sometime in the past of running fluid, possibly water. The chemical nature of water is thus one we must examine as it permeates living systems: Water can exist in all three states of matter on Earth, while only in one state on our two nearest neighboring planets. The above graph is from http: Water is polar covalently bonded within the molecule.

This unequal sharing of the electrons results in a slightly positive and a slightly negative side of the molecule. Other molecules, such as Ethane, are nonpolar, having neither a positive nor a negative side, as shown in Figure 2. The difference between a polar water and nonpolar ethane molecule is due to the unequal sharing of electrons within the polar molecule.

Nonpolar molecules have electrons equally shared within their covalent bonds. Image from Purves et al. These link up by the hydrogen bond discussed earlier. Consequently, water has a great interconnectivity of individual molecules, which is caused by the individually weak hydrogen bondsshown in Figure 3, that can be quite strong when taken by the billions.

Formation of a hydrogen bond between the hydrogen side of one water molecule and the oxygen side of another water molecule. Water has been referred to as the universal solvent. Living things are composed of atoms and molecules within aqueous solutions solutions that have materials dissolved in water. Solutions are uniform mixtures of the molecules of two or more substances. The solvent is usually the substance present in the greatest amount and is usually also a liquid.

The substances of lesser amounts are the solutes. The solubility of many molecules is determined by their molecular structure. You are familiar with the phrase "mixing like oil and water.

The dipolar nature of the water molecule

The polar covalently bonded water molecules act to exclude nonpolar molecules, causing the fats to clump together. The structure of many molecules can greatly influence their solubility. Sugars, such as glucose, have many hydroxyl OH groups, which tend to increase the solubility of the molecule. This aspect of water is illustrated in Figure 4. Dissolution of an ionically bonded compound, sodium chloride, by water molecules.

In this disassociation, the oxygen retains the electrons and only one of the hydrogens, becoming a negatively charged ion known as hydroxide. Basic solutions have the opposite. The pH of several common solutions is shown in Figure 5.

Logarithms are exponents to which a number usually 10 has been raised. Organic molecules Back to Top Organic molecules are those that: Methane CH4 is an example of this. If we remove the H from one of the methane units below, and begin linking them up, while removing other H units, we begin to form an organic molecule.

Not all methane is organically derived, methane is a major component of the atmosphere of Jupiter, which we think is devoid of life. When two methanes are combined, the resultant molecule is Ethane, which has a chemical formula C2H6.

Inorganic Chemistry - Water

Molecules made up of H and C are known as hydrocarbons. The formulas and structural representations of several simple organic molecules are shown in Figure 6. Types of hydrocarbon compounds and their structure. Images from Purves et al. Scientists eventually realized that specific chemical properties were a result of the presence of particular functional groups. Functional groups are clusters of atoms with characteristic structure and functions.

Nonpolar molecules are repelled by water and do not dissolve in water; are hydrophobic. Hydrocarbon is hydrophobic except when it has an attached ionized functional group such as carboxyl acid COOHthen molecule is hydrophilic. One of the most common groups is the -OH hydroxyl group.

Its presence will enable a molecule to be water soluble. Isomers are molecules with identical molecular formulas but differ in arrangement the characteristics of the molecules of water in chemistry their atoms e. Selected functional groups and related data are shown in Figure 7. Functional groups in organic molecules. Carbon has four electrons in outer shell, and can bond with up to four other atoms usually H, O, N, or another C. Since carbon can make covalent bonds with another carbon atom, carbon chains and rings that serve as the backbones of organic molecules are possible.

Chemical bonds store energy. The C-C covalent bond has 83. Energy is in two forms: Chemical bonds are potential energy, until they are converted into another form of energy, kinetic energy according to the two laws of thermodynamics.

  1. This covalent bond is known as a pyrophosphate bond. We will learn more about the DNA structure and function later in the course click here for a quick look [actually take all the time you want!
  2. This value differs from that for ice in Table 4 due to both temperature and phase differences.
  3. The energy required in freeze-drying processes varies, depending on temperature and other conditions. Be prepared to make a sketch and name the three parts of every amino acid.
  4. The solubility of many molecules is determined by their molecular structure. Of course, the precise relationship depends on the material in question.

Each organic molecule group has small molecules monomers that are linked to form a larger organic molecule macromolecule. Monomers can be jouined together to form polymers that are the large macromolecules made of three to millions of monomer subunits.

  1. They are highly toxic, yet abundant.
  2. Formation of a peptide bond between two amino acids by the condensation dehydration of the amino end of one amino acid and the acid end of the other amino acid. These classes perform a variety of functions in cells.
  3. A large body of water moderates climate. Molecules strongly interact with or love water molecules are hydrophilic, due to hydrogen bonding, polar-ionic or polar-polar attractions.

Macromolecules are constructed by covalently bonding monomers by condensation reactions where water is removed from functional groups on the monomers. Cellular enzymes carry out condensation and the reversal of the reaction, hydrolysis of polymers. Condensation involves a dehydration synthesis because a water is removed dehydration and a bond is made synthesis. When two monomers join, a hydroxyl OH group is removed from one monomer and a hydrogen H is removed from the other.

This produces the water given off during a condensation reaction.

Fundamental Characteristics of Water

Hydrolysis hydration reactions break down polymers in reverse of condensation; a hydroxyl OH group from water attaches to one monomer and hydrogen H attaches to the other. There are four classes of macromolecules polysaccharides, triglycerides, polypeptides, nucleic acids. These classes perform a variety of functions in cells. Carbohydrates have the general formula [CH2O]n where n is a number between 3 and 6.

Chemical Characteristics and Functions of Water in Physiology

Note the different CH2O units in Figure 8. Carbohydrates function in short-term energy storage such as sugar ; as intermediate-term energy storage starch for plants and glycogen for animals ; and as structural components in cells cellulose in the cell walls of plants and many protistsand chitin in the exoskeleton of insects and other arthropods.

Sugars are structurally the simplest carbohydrates. They are the structural unit which makes up the other types of carbohydrates. Important monosaccharides include ribose C5H10O5glucose C6H12O6and fructose same formula but different structure than glucose. We classify monosaccharides by the number of carbon atoms and the types of functional groups present in the sugar. For example, glucose and fructose, illustrated in Figure 9, have the same chemical formula C6H12O6but a different structure: This functional group difference, as small as it seems, accounts for the greater sweetness of fructose as compared to glucose.

Models of glucose and fructose. In an aqueous solution, glucose tends to have two structures, a alpha and b betawith an intermediate straight-chain form shown in Figure 10. The a form and b form differ in the location of one -OH group, as shown in Figure 9. Glucose is a common hexose, six carbon sugar, in plants.

The products of photosynthesis are assembled to form glucose. Energy from sunlight is converted into and stored as C-C covalent bond energy. This energy is released in living organisms in such a way that not enough heat is generated at once to incinerate the organisms. One mole of glucose yields 673 Kcal of energy.

Water Molecule -- Chemical and Physical Properties

A calorie is the amount of heat needed to raise one gram of water one degree C. A Kcal has 1000 times as much energy as a cal. Glucose is also the form of sugar measured in the human bloodstream. D-Glucose in various views stick and space-filling from the web.

Right image from Purves et al. Disaccharides are formed when two monosaccharides are chemically bonded together. Sucrose, a common plant disaccharide is composed of the monosaccharides glucose and fructose. Lactose, milk sugar, is a disaccharide composed of glucose and the monosaccharide galactose. The maltose that flavors a malted milkshake and other items is also a disaccharide made of two glose molecules bonded together as shown in Figure 11.

Formation of a disaccharide top by condensation and structure of two common disaccharides. Polysaccharides are large molecules composed of individual monosaccharide units. A common plant polysaccharide is starch shown in Figure 12which is made up of many glucoses in a polypeptide these are referred to as glucans. Two forms of polysaccharide, amylose and amylopectin makeup what we commonly call starch.

  • Note the different CH2O units in Figure 8;
  • Be able to list the three most abundant elements in living things;
  • Enzymes are a special class of proteins that speed up chemical reactions in cells;
  • The water molecule forms an angle, with hydrogen atoms at the tips and oxygen at the vertex;
  • Macromolecules are constructed by covalently bonding monomers by condensation reactions where water is removed from functional groups on the monomers.

The formation of the ester bond by condensation the removal of water from a molecule allows the linking of monosaccharides into disaccharides and polysaccharides. Glycogen see Figure 12 is an animal storage product that accumulates in the vertebrate liver. Images of starch topglycogen middleand cellulose bottom. Cellulose, illustrated in Figure 13 and 14, is a polysaccharide found in plant cell walls.