Biology 1225 Chapter Notes - Chapter 2: Chemical Polarity, Hydrogen Bond, Chemical Bond

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greentortoise759

8 Mar 2018

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2 polar covalent bonds in each water molecule. No charge: o has slight negative charge and h has slight positive charge, polar -> attaches. Hydrogen bond: attraction between covalently bonded hydrogen atom and another atom them together taking part in separate polar covalent bond. Do not make molecules out of atoms, not chemical bond. Form and break more easily than covalent or ionic. Polarity and ability to form hydrogen bonds make water excellent solvent. Hydrophilic: substance that dissolves in water easily, water-loving. Bonds between many molecules is stronger than ionic bonds with 2 molecules. Solvent: liquid in which substances dissolve in. Chemical bonds do not form between molecules of solute and solvent -> proportions can vary. Non-ionic substances can dissolve easily in water. Have one or more polar covalent bond. Hydrogen bonds collectively exert continuous pull on its individual molecules. Overcoming waters cohesion takes energy -> evaporation sucks energy from liquid water and lowers water"s surface temperature.

Related Questions

Ionic bonds are formed when two opposite charged ions (formed when atoms lose or gain electrons) encounter each other. These bonds can be viewed as âextreme polar covalent bondsâ as one atom is in total control of the otherâs electron(s). Why are ionic bonds so much weaker when they are in water?

A.	Ionic compounds such as salts are hydrophilic, so they prefer to form bonds with water molecules over other compounds.

B.	Water molecules readily form covalent bonds to charged particles and, as these bonds are stronger than ionic bonds, the ionic bonds are pulled apart.

C.	Water molecules shorten the size of covalent bonds and this weakens ionic interactions.

D.	Water molecules readily donate electrons and nullify the positively charged ions.

E.	Polar water molecules can physically interfere with the polar (positive/ negative) charged attraction between ions and thus the ionic bonds are disrupted and weakened.

Circle the word of phrase that correctly completes the sentece or answers the question. The property that allows water molecule to be attracted to each other is called (cohesion, adhesion). This propert is conferred by (covalent bonds, hydrogen gonds). This property is conferred by ( covalent bond, hydrogen bond). Ice is ( more dense, less dense) than liquid water. Water is polar molecule because of the unequal sharing of( electrons, protons) between the atoms in H2O. Adhesion of water to a surface is through the action of (covalent bond, ionic bonds, hydrogen bonds) between the water and the surace. Water is converted from liquid to vapor through the brakage of ( colvalent, hydrogen) bonds. Which (one) of these substance is not hydrophilic:( cellulose, oil, NaCl). Which of these will not dissolve in water, even though it is polar?(cellulose, oil, NaCl). Which of these is an electrolyte? (cellusose oil, NaCl). A buffer will contain a week acis , weak base, both).

The type of macromolecule found in highest concentration on a weight basis in a HeLa cell is

protein.

lipid.

polysaccharide.

nucleic acid.

water

Co and Zn ions are required by humans in

microgram amounts.

gram or near gram amounts.

kilogram amounts.

d. milligram amounts.

Which description best characterizes the length of a hydrogen bond between water molecules?

About the same length as the calculated van der Waals distance for two water molecules.

About the same length as a covalent O----H bond.

Shorter than a covalent O---H bond.

Longer than a covalent O---H bond, but shorter than the calculated van der Waals distance between water molecules.

Which of the following statements about water is not true?

Water will hydrogen bond into highly ordered structures or "cages" around non-polar molecules.

The electron-rich oxygen atom of one water molecule can interact with an electron-poor hydrogen on another water molecule to form a hydrogen bond.

Water is a key player in the energetics of the hydrophobic effect.

In an ice crystal water molecules pack into open lattices consisting of five-membered oxygen rings.

At 25 degrees celsius liquid water is about 85% as hydrogen bonded as the water in ice, with each molecule in an average of 3.4 hydrogen bonds.

Which of the following is the strongest?

Ionic interactions

Permanent dipole - permanent dipole interactions

London dispersion forces

Co-linear hydrogen bonds

Which of the following is the best explanation for the hydrophobic effect?

It is caused by the attraction of hydrophobic groups for each other.

It is an entropic effect caused by the tendency of hydrophobic groups to increase their entropy by associating with other hydrophobic groups.

It is an entropic effect, caused by the tendency of water molecules to increase their entropy by excluding hydrophobic groups, which they must otherwise surround with highly ordered structures.

It is caused by the attraction of water for hydrophobic groups.

It is an entropic effect, caused by the tendency of water molecules to increase their entropy by forming highly ordered structures around the hydrophobic groups.

Which of the following is NOT defined as a buffer? (pKa PIPES-H⁺ = 6.76; pKa MOPS-H⁺ = 7.15; pKa HEPES-H⁺ = 7.47)

0.15 M MOPS, pH 6.50

0.05 M HEPES-H⁺ / 0.04 M HEPES

0.20 M PIPES, pH 7.97

0.01 M HEPES, pH 7.30

Biology 1225 Chapter Notes - Chapter 2: Chemical Polarity, Hydrogen Bond, Chemical Bond

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