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