Chapter 2 life chemistry and water Flashcards
element
a pure substance that cannot be broken into simpler substances by ordinary chemical or physical techniques
trace elements (2)
- an element that occurs in organisms in very small quantities (less than 0.01%) ;
- in nutrition, a mineral required by organisms only in small amounts
Avogadro’s number
the number 6.022 X 10~23 derived by dividing the atomic weight of any element by the weight of an atom of that element
molecule
a unit composed of atoms combined chemically in fixed numbers and ratios
formula
the name of a molecule written in chemical shorthand
compounds
a molecule whose component atoms are different
isotopes
a distinct form of atoms of an element, all with the same number of protons but a different number of neutrons and therefore a different mass/ nucleon number
Daltons (Da)
a standard unit of mass, about 1.66 x 10~-24 grams
molarity (M)
the number of moles of a substance dissolved in 1 litre of solution
pH scale
the numerical scale from 0 to 14 used by scientists to measure acidity
weight
a measure of the pull of gravity on an object
radioactivity
the giving off of particles of matter and energy by decaying nuclei
radioisotope
an unstable, radioactive isotope
radiometric dating
a dating technique that uses the clockwork decay of unstable isotopes to estimate the age of organic material, rocks, or fossils that contain them
orbital (2)
- the region of space where the electron occupies most of the time.
- a region of space around the nucleus of an atom that can be occupied by one or two electrons
shells/ energy levels
regions of space within an atom where electrons are found
valence electron
an electron in the outmost energy level of an atom
base
proton acceptor that reduces the H+ concentration of a solution
ionic bond
a bond that results from electrical attractions between atoms that gain or lose valence electrons completely
ion
a positively or negatively charged atom
anion
a negatively charged ion
ice lattice
a rigid, crystalline formed when a water molecule in ice forms 4 hydrogen bonds with neighboring molecules
non-polar covalent bond
bond in which electrons are shared equally or nearly equally; the atoms have NO charge
reactants
the atoms or molecules entering a chemical reaction
non-polar association
association that occurs when non-polar molecules clump together
hydrophilic
polar molecules that associate readily with water
hydrophobic
non-polar molecules/substances that are excluded by water and other polar molecules
hydrogen bond
non-covalent bond formed by unequal electron sharing between hydrogen atoms and oxygen , nitrogen, or sulfur
solute
the molecules of a substance dissolved in water.
concentration
the number of molecules or ions of a substance in a unit volume of space
molecular weight
the weight of a molecule in grams, equal to the total mass number of its atoms
heat of vaporization
the heat required to give water molecules enough energy of motion to break loose from liquid water and form a gas
water lattice
an arrangement formed when a water molecule in liquid establishes an average of 3.4 hydrogen bonds with its neighbors
kilocalorie (kcal)
the amount of heat required to raise 1 kg of water by 1 degree Celsius, the scientific unit equivalent to a Calorie and equal to a 1000 small calories
matter
anything that occupies space and has mass
atom
the smallest unit that retains the chemical and physical properties of an element
atomic nucleus
the nucleus of a atom, which consists of sub-atomic particles called protons and neutrons
proton
a subatomic particle situated in the nucleus of an atom that carries one unit of charge
neutron
uncharged subatomic particle in the nucleus of an atom
electron
negatively charged particle situated outside the nucleus of an atom
atomic number
the number of protons in the nucleus of each kind of atom
mass number
the total number of protons and neutrons in the atomic nucleus
mass
- the amount of matter in an object.
2. my definition: the degree to which a body is reluctant to a change in motion
tracer
isotope used to label molecules so that they can be tracked as they pass through biochemical reactions
chemical bond
link formed when atoms of reactive elements combine into molecules
cation
a positively charged ion
polar covalent bond
bond in which electrons are shared unequally
electronegativity
the measure of the tendency of an atom to attract electrons to itself in a chemical bond ( that is, to become negative)
polar association
association that occurs when polar molecules attract and align themselves with other polar molecules and with charged ions and molecules
van der waal’s forces
weak molecular attractions over short distances
molecular geometry
the 3-dimensional arrangement of atoms in a molecule, in other words, its shape
reactant
the atoms or molecules entering a chemical reaction
product
an atom or molecule leaving a chemical reaction
chemical equation
a chemical reaction written in balanced form
specific heat
the amount of heat required to increase the temperature of a given quantity of water
cohesion
the high resistance of water molecules to separation
surface tension
the force that places surface water molecules under tension, making them more resistant to separation than the underlying water molecules
bilayer
a membrane with 2 molecular layers
hydration layer
a surface coat of water molecules that covers other polar molecules and charged molecules and ions
solution
substance formed when molecules and ions separate and are suspended individually , surrounded by water molecules
solvent
the water in a solution in which the hydration layer prevents polar molecules or ions from re-associating
solute
the molecules of a substance dissolved in water
atomic weight
the weight of an element in grams, equal to the mass number
molecular weight
the weight of a molecule in grams, equal to the total mass number of its atoms
mole (mol)
amount of substance that contains as many atoms or molecules as there are atoms in exactly 12g of carbon-12, which is 6.022 x 10~23
dissociation
the separation of water to produce positively charged hydrogen ions and hydroxide ions
reversible
the term indicating that a reaction may go from left to right or from right to left, depending on conditions
acid
proton donor that releases H+ ions (and anions) when dissolved in water
base
proton acceptor that reduces the H+ concentration of a solution
acidity
the concentration of H+ ions in a water solution, compared with the concentration of OH- ions
acid precipitation
rainfall with low pH, primarily created when gaseous sulfur dioxide (SO2) dissolves in water vapor in the atmosphere, forming sulfuric acid
