Bio Ch 2 Flashcards
Elements
Substance that cannot be broken down to simpler substances with different properties
Matter
Anything that takes up space and has mass
CHNOPS
Carbon, hydrogen, nitrogen, oxygen, phosporus, & sulfur- basic elements of life (95% of the body weight of organisms)
Atom
Smallest part of an element that displays the properties of the element
atomic symbol
1-2 letters that represent an element’s name
Proton
Positively charged subatomic particle
Neutrons
Uncharged subatomic particles
Electrons
Negatively charged subatomic particles (Gk, elektron, electricity)
Electron shell
average location of electrons
Atomic number
of protons in the nucleus; accounts for unique properties of the atom
Mass number
sum of protons and neutrons in nucleus
Atomic mass
average of the AMU for all isotopes of that number
Isotopes
Gk, isos, equal & topos, place; atoms of the same element that differ in the number of neutrons
Tracer
small amount of a radioactive isotope in a sample to detect molecular changes
Octet rule
outermost shell of an atom is most stable when it has eight electrons
Valence shell
atoms use electrons in this shell to undergo reactions; # of electrons determines whether the atom gives up, accepts, or shares electrons to acquire 8 in the outer shell
Molecule
Latin = moles, “mass”; 2+ elements bond together; smallest part of a compound that retains its chemical properties
Compound
molecule with at least 2 elements
Formula
number of each kind of atom in a molecule
Ions
charged particles
Ionic bond
strong attraction between negatively and positively charged ions that holds ionic compounds together
Salts
solid substances that usually separate and exist as individual ions in water
Covalent bond
Latin, co, together/with & valens, strength); 2 atoms share electrons in such a way that each atom has an octet of electrons in the outer shell (or 2 electrons, in the case of hydrogen)
Nonpolar covalent bond
sharing of electrons between 2 atoms are equal
Electronegativity
ability to attract electrons; dependent on number of protons (the greater the protons, the greater the electronegativity)
Polar covalent bond
when electrons are not shared equally
Hydrogen bond
attraction of a slightly positive hydrogen to a slightly negative atom in the vicinity
Calorie
amount of heat energy needed to raise the temperature of 1g of water 1 degree Celsius
Solution
fluid that contains a dissolved solid
Solute
Dissolved substances in solution
Hydrophilic
molecules that can attract water (Gk, hydrias, of water & phileo, love)
Hydrophobic
nonionized and nonpolar molecules that cannot attract water (Gk, hydrias, of water & phobia, fear)
Cohesion
ability of water molecules to cling to each other due to hydrogen bonding
Adhesion
ability of water molecules to cling to other polar surfaces
Surface tension
force that holds moist membranes together due to the attraction of water molecules through hydrogen bonds
Hydrogen ions (H+)
Protons; hydrogen atom that has lost its electron and therefore bears a positive charge
Hydroxide ions (OH-)
1 of 2 ions that results when a water molecule dissociates; it has gained an electron and therefore bears a negative charge
Acids
substances that dissociate in water, releasing hydrogen ions (H+); acidity depends on how fully it dissociates in water
Bases
Substances that either take up hydrogen ions (H+) or release hydroxide ions (OH-)
pH scale
used to indicate the acidity or basicity/alkalinity of a solution
Buffer
chemical or combo of chemicals that keeps pH within normal limits
