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Flashcards in Chapter 2 Deck (63):
1

bioremediation

applications of chemical and biological knowledge to decontaminate polluted environments

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element

pure substance that cannot be broken down into simpler substances

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matter

anything that occupies space and has mass

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trace elements

elements that occur in very small amount in organisms

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atoms

smallest units that retain the chemical and physical properties of an element

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molecules

atoms combined chemically in fixed numbers and ratios

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formula

name of a molecule written in chemical shorthand

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compounds

molecules whose component atoms are different

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protons

positively charged particles in nucleus

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atomic number

number of protons in the nucleus of an atom

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neutrons

uncharged particles in the nucleus

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isotopes

an atom with the same number of protons but with a different number of neutrons

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dalton

standard unit of mass

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mass number

based on the total number of protons and neutrons in an atom

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radioactivity

giving off particles of matter and energy that can be detected

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radioisotope

unstable radioactive isotope

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tracers

isotopes used to label molecules so that they can be tracked as they pass biochemical reactions

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orbital

the region of space where the electron is most of the time

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energy levels/shells

regions of space where electrons are found

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valence electrons

electrons in the outermost energy level of an atom

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chemical bonds

when reactive elements combine into molecules

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ionic

results from electrical attractions between atoms that gain and lose valence electrons completely

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ions

charged particles

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cation

positively charged ion

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anion

negatively charged ion

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covalent bond

atoms sharing valence electrons

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electronegativity

measure of atom's attraction for the electrons sharing in a bond

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nonpolar covalent bonds

electrons are shared equally

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polar covalent bonds

electrons are not shared equally

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polar associations

polar molecules aligning themselves with other polar molecules or ions

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nonpolar associations

excluded nonpolar molecules that clump together

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hydrophilic

associate readily with water

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hydrophobic

excluded by polar molecules

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hydrogen bond

when hydrogen atoms are in a covalent bond and then show some attraction to other ions or molecules

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van der waals forces

weakest forces that occur at very small distances because electrons accumulate by chance in one part of the molecule

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reactants

atoms or molecules entering a chemical reaction

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products

atoms or molecules leaving a reaction

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chemical equations

chemical reactions written in balanced form

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water lattice

structure of water that allows hydrogen bonds to constantly break and reform

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ice lattice

structure of ice that spaces the molecules farther apart decreasing the density

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specific heat

amount of energy required to increase the temperature of a given quantity of water

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calories

calorie refers to a kilocalroie

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heat of vaporization

required heat to break loose liquid water and form a gas

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cohesion

high resistance of water molecules to separation provided by hydrogen bonding lattice

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adhesion

molecules stick to walls of tubes by forming hydrogen bonds with charged polar groups in molecules that form the walls

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surface tension

forced created by the unbalanced bonding that places the surface water molecules under tension that makes them more resistant to separation than the underlying molecules

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bilayer

created by exclusion by water molecules of lipid molecules to associate into a second layer

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hydration layer

surface coat that reduces the tension between molecules or ions and promotes separation onto a solution; caused by water coating surfaces of other polar molecules

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solution

mixture when atoms are suspended individually separated by water molecules

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solvent

the dissolving agent of a solution

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solute

substance dissolved into solvent or water

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concentration

number of molecules or ions of a substance in a unit volume

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atomic weight

weight in grams equal to the mass number

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avogadros number

6.02 x 10^23

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molecular weight

sum of atomic weights of all the atoms in the molecule

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mole

6.02x10^23 molecules or atoms

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molarity

number of mole per liter

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dissociate

separate into the individual ions that make up a compound

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reversible

a reaction may go either to the left or right

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acids

proton donors that release h+ when dissolved in water

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bases

proton acceptors that reduce the H+ concentration of a solution

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acidity

determined by the h+ concentration

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buffers

substances that compensate for ph changes by absorbing or releasing h+