[Chapter 2] Life's Chemical Basis

Question 1

Periodic Table

Answer 1

How elements (pure substances) are organized.. Protons having a positive charge, electrons having a negative charge, and neutrons having no charge at all. Created by Dmitri Mendeleev (known for his great hair :P)

Question 2

Henri Becquerel

Answer 2

In 1896, Henri left some crystals of uranium salt in his desk drawer which produced negative images on his film. This proved the existence of radioisotopes (he called them invisible radiations)

Question 3

Radioactive Decay

Answer 3

The process of transforming one element into another. It occurs independently of external factors and it will always decay at a constant rate.

Question 4

Tracer

Answer 4

Any molecule with a detectable substance attached. Typically, a radioactive tracer is a molecule in which radioisotopes have been swapped for 1+ atoms.

Question 5

PET

Answer 5

Positron-Emission Tomography: allows people to see cell activity. The tracer, such as a radioactive sugar, is injected into a patient who is then moved into a PET scanner.Cells will take up the tracer at different rates and detects radioactive decay where ever the tracer is. This produces an image on a computer monitor and can reveal cell abnormalities.

Question 6

Shell Model

Answer 6

Used to check the cell for vacancies. (check out figure 2.6 and 2.7 on page 24 and 25)

Question 7

Electronegativity

Answer 7

The measure of an atom’s ability to pull electrons from other atoms. Whether the pull is strong or weak depends on the atoms size and how many vacancies it has; it is not a measure of charge.

Question 8

Chemical Bond

Answer 8

An attractive force that arises between 2 atoms when their electrons interact.

Question 9

Molecule

Answer 9

Formed when 2+ atoms of the same or different elements join in chemical bonds.

Question 10

Compounds

Answer 10

are molecules that consist of 2+ different elements in proportions that do not vary. (ex. water)

Question 11

Mixture

Answer 11

2+ substances intermingle, and their proportions can vary because the substances do not bond with each other (ex. sugar in water)

Question 12

Ionic Bonds

Answer 12

Bond in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other.

Question 13

Covalent Bonds

Answer 13

bond in which one or more pairs of electrons are shared by two atoms. A line represents a single covalent bond, 2 lines represents a double covalent bond, and 3 lines represents a triple covalent bond. See table 2.1, 2.8, 2.9 on page 26 and 27

Question 14

Polar Covalent Bond

Answer 14

forms between 2 elements with a small different in electronegativity. The atoms do not share electrons equally.

Question 15

Non-polar Covalent Bonds

Answer 15

2 atoms of identical electronegativity share electrons equally and there is no difference of charge between the 2 ends of the bond.

Question 16

Polarity

Answer 16

separation of charge into distinct positive and negative regions.

Question 17

Hydrogen Bond

Answer 17

an attraction between an hydrogen atom and an electronegative atom, both of which are taking part in separate polar covalent bonds. (Table 2.10 page 27)

Question 18

Hydrophilic

Answer 18

Molecules which will likely form bonds with water due to its polarity. Polar molecules and sugars are likely to form bonds with water.

Question 19

Hydrophobic

Answer 19

Molecules that will not likely form bonds with water such as oil molecules.

Question 20

Temperature

Answer 20

How the energy of molecular motion is measured.

Question 21

Water Molecule

Answer 21

Has a bent shape with a slightly negative end (oxygen) that is balanced by its slightly positive ends (hydrogen) See table 2.11 page 28

Question 22

Evaporation

Answer 22

When the temperature of water is below its boiling point hydrogen bonds form as fast as they break. While the water gets hotter the increase in molecular motion keeps bonds from forming so individual molecules at the surface escape into the air.

Question 23

Benefits of Evaporation

Answer 23

cooling off when you sweat in hot, dry weather.

Question 24

Solvent

Answer 24

Is a substance (usually a liquid) which dissolves other substances.

Question 25

Solute

Answer 25

The substance which is dissolved.

Question 26

Sphere of hydration

Answer 26

A cluster of water molecules around a solute. Such spheres form around any solute in cellular fluids, tree sap, blood, the fluid in your gut, and all fluids associated with life.

Question 27

Cohesion

Answer 27

Molecules resist separating from one another which allows for surface tension. Cohesion also works inside organisms (ex. plants absorb nutrient-laden water while they grow).

Question 28

pH scale

Answer 28

the measure of hydrogen ion concentration in solutions. The greater the H+ concentration the lower the pH (see table 2.14 page 30)

Question 29

Acids

Answer 29

Donate hydrogen ions

Question 30

Bases

Answer 30

Accept Hydrogen ions

Question 31

Weak Acids

Answer 31

stingy H+ donors (carbonic acid)

Question 32

Strong Acids

Answer 32

readily give up H+ in water (hydrochloric acid)

Question 33

Buffer System

Answer 33

A set of chemicals (often a weak acid or base) which keeps a solution stable

Question 34

Buffer System Failure

Answer 34

Ex Acute respiratory acidosis causes carbon dioxide to accumulate and form excess carbonic acid in the blood.

Question 35

Strong Acids and Bases

Answer 35

Can kill organsims and cause severe chemical burns

Question 36

Salt

Answer 36

Any compound which will dissolve easily into water other than H+ and OH-