Ch2-P45-56 Flashcards Preview

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Flashcards in Ch2-P45-56 Deck (20):


 are variants of a particular chemical element: while all isotopes of a given element share the same number of protons, each isotope differs from the others in its number of neutrons.


isotope - iso = ; top =

iso = same; top = place (ie same position in the periodic table)


Covalent bond?

sharing of electrons


Ionic bond?

attraction of cation to anion



Are substances that ionize in water (acids, bases, or salts) and form  solutions capable of conducting electricity.


Free radicals 

Are chemical particles with an odd number of electrons. For example, oxygen normally exists as a stable molecule composed of two oxygen atoms, O2; but if an additional electron is added, it becomes a free radical called the superoxide anion, O2− . Free radicals are represented with a dot to symbolize the odd electron.



An antioxidant is?

 a chemical that neutralizes free radicals. 


nonpolar and polar covalent bonds explain?

(a) A nonpolar covalent bond between two carbon atoms, formed by electrons that spend an equal amount of time around each nucleus, as represented by the symmetric blue cloud.

(b) A polar covalent bond, in which electrons orbit one nucleus significantly more than the other, as represented by the asymmetric cloud. This results in a slight negative charge (δ −) in the region where the electrons spend most of their time, and a slight positive charge (δ +) at the other pole.


A hydrogen bond is?

 a weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another. Water molecules, for example, are weakly attracted to each other by hydrogen bonds.


Van der Waals forces are?

 weak, brief attractions between neutral atoms. When electrons orbit an atom's nucleus, they do not maintain a uniform distribution but show random fluctuations in density. If the electrons briefly crowd toward one side of an atom, they render that side slightly negative and the other side slightly positive for a moment. If another atom is close enough to this one, the second atom responds with disturbances in its own electron cloud. Oppositely charged regions of the two atoms then attract each other for a very short instant in time.

A single van der Waals force is only about 1% as strong as a covalent bond, but when two surfaces or large molecules meet, the van der Waals forces between large numbers of atoms can create a very strong attraction. This is how plastic wrap clings to food and dishes; flies and spiders walk across a ceiling; and even a 100 g lizard, the Tokay gecko, can run up a windowpane.


Explain hydrophilic and hydrophobic?

Substances that dissolve in water, such as sugar, are said to be hydrophilic (HY-dro-FILL-ic); the relatively few substances that do not, such as fats, are hydrophobic (HY-dro-FOE-bic). 


What is an acid and a base?

An acid is any proton donor, a molecule that releases a proton (H+) in water. A base is a proton acceptor. 


Energy is........., which means?

Energy is the capacity to do work. To do work means to move something, whether it is a muscle or a molecule. Some examples of physiological work are breaking chemical bonds, building molecules, pumping blood, and contracting skeletal muscles. All of the body's activities are forms of work.


Explain potential and kinetic energy.

 Potential energy is energy contained in an object because of its position or internal state but that is not doing work at the time. Kinetic energy is energy of motion, energy that is doing work.


Chemical energy is?

  potential energy stored in the bonds of molecules.


Heat is?

 the kinetic energy of molecular motion.


Electromagnetic energy is

 the kinetic energy of moving “packets” of radiation called photons. The most familiar form of electromagnetic energy is light. 


Electrical energy ?

has both potential and kinetic forms. It is potential energy when charged particles have accumulated at a point such as a battery terminal or on one side of a cell membrane; it becomes kinetic energy when these particles begin to move and create an electrical current—for example, when electrons move through your household wiring or sodium ions move through a cell membrane.


Free energy is?

 the potential energy available in a system to do useful work. In human physiology, the most relevant free energy is the energy stored in the chemical bonds of organic molecules.


A chemical reaction is?

 a process in which a covalent or ionic bond is formed or broken.