ATI TEAS Science chemistry.

anything that has mass and takes up space -all matter is composed of atoms -has 4 states caused by differences in distances/angles btwn molecules/atoms, which results in diff bonding energy -states can be traversed by addition/removal of heat -ex: solid to liquid: enough heat to traverse latent heat of fusion of solid -ex: liquid to gas: enough heat to traverse latent heat of vaporization of liquid matter -structures are rigid or nearly rigid and have strong bonds -definite volume and shape -high density -virtually no compressibility -molecules vibrate around fixed positions solid -move around and have weak bonds, but not weak enough to readily break -volume remains constant but it assumes shape of its container -high density -virtually no compressibility -molecules move freely past eachother liquid -move almost independently of eachother -far apart, usually no bonds -assume volume/shape of its container -low density -high compressibility -molecules have very free motion gas ionized gas that has some electrons that are described as free b/c they aren't bound to an atom or molecule (TEAS doesn't ask about this) plasma -melting: solid to liquid -freezing: liquid to solid -liquid to gas: vaporization -gas to liquid: condensation -gas to solid: sublimation -solid to gas: deposition changes in matter -can bond together to make molecules -nucleus (positive charge): protons (fixed) and neutrons (varies), more mass then rest of atom -protons: positive charge -neutrons: neutral charge -electrons: negative charge -atoms with equal # of protons and electrons are electrically neutral (stable) atoms -change in liquid to gas form BELOW its boiling point -some molecules at surface maintain enough heat energy to escape cohesive force by other molecules -at high temps, molecules move more rapidly, increasing # w/enough energy to break from liquid form -rate of evap is higher if larger liquid surface is exposed -amt of moisture already in air affects evap rate (if alot, then some evap molecules will return to liquid) -atmospheric pressure can speed up/down evap rate evaporation -change in gas to liquid form -opposite of evap or vape -when temp decreases, component molecules move slower -slower motion allows for intermolecular cohesive forces to pull them together (in H2O, H bonds established) -can also be caused by increased pressure on a gas, which decreases volume -hydrologic cycle: process initiated when warm air containing water vapor rises and then cools; occurs due to convection in air, meteorological fronts, or lifting over high land formations condensation average distance btwn the nucleus and outermost electron atomic radius -electron cloud: electrons orbit nucleus -atomic models are not to scale -bohr model: electrons orbit nucleus like planets orbit sun -lewis model: lewis dot diagram, shows bonded pairs and lone electrons, drawn for covalent bonding -electron config model: shows electrons in each level of orbit atomic models -number of protons in atom -unique identifier -represented as "Z" -atoms w/neutral charge have atomic # that is equal to # of electrons -shows # of electrons needed to be stable atomic number -aka mass # -total # of protons and neutrons in the nucleus -represented as "A" -A = Z + N ("N" is # neutrons) -mass of electrons insignificant because so small -relative atomic mass: atomic weight called this sometimes, but don't confuse w/atomic mass -atomic weight: ratio of average mass per atom in a sample to 1/2 mass of an atom of C-12 atomic mass -256 known stable isotopes, 80 atoms have one or more -varying number of neutrons in nucleus -denoted by element symbol, preceded by atomic mass number in superscript and atomic number in subscript -stable: not observed to decay -unstable: radioactive, unstable nuclei so undergoes random nuclear reactions which causes particles (radiation) to be emitted -decay start is unpredictable, but decay rate is predictable -decay rate used to estimate age of materials w/certain radioactive isotopes isotopes -most atoms neutral b/c of protons/electrons being equal -electrons transferred btwn atoms when come in contact, creates atom/molecule that has pos or neg charge -anion (neg ion): when atoms gain electrons -cation (pos ion): when atoms lose electrons -ionization: process by which neutral particles are ionized into charged particles (ex: gases & plasmas can be partially or fully charged thru ionization) ions -a union between electron structures of atoms -neg/pos attraction btwn electron(s) & nucleus (nuclei) -attraction keeps atom cohesive, allows bonds w/other atoms & molecules -each of 4 shells have max electron #, each must be filled before electrons added to valence shell -farther away electron is from nucleus, the more energy it has -bonds form/break btwn atoms when gain/lose/share electron in valence shell chemical bonds -negative, subatomic particles that orbit nucleus at various layers, shells, or clouds -account for tiny fraction of atom's weight -part of lepton family of elementary particles -can have various distances from nucleaus -occupy lowest energy level possible -stable: all electrons in lowest available positions -valence shell: outermost electron shell, electrons called valence electrons, determines bonding behavior -atoms react to fill/empty valence shell electrons -K shell: 1st shell, max of 2 electrons -L shell: 2nd shell, max of 8 electrons -M shell: 3rd shell, max of 18 electrons -N shell: 4th shell, max of 32 electrons -shells can also have subshells electron shells -molecules or crystalline solids: atoms of same element bond -compound: two or more different atoms bond -physical properties of compounds reflect interaction of its molecules; determined by structure of molecules and distance/angle btwn the atoms bonds between atoms -bond btwn two oppositely charged ions -atom gains/loses electrons to become neg/pos ion -xfers electrons from one atom to another -resulting compound is neutral ionic bond -atoms share electrons with other atoms or with another covalent bond -bond is always stronger then H bonds, similar in strength to ionic -electron sharing: occurs more with atoms with similar electronegativity -non-metals more likely to form then metals since harder to give an electron -polar: one end neg, other end pos -non-polar covalent: electrons shared equally -polar covalent bond: electrons shared unequally covalent bond -when atom of molecule interacts with hydrogen atom in same area -weak bond, easily broken (short lived), numerous -can form btwn two parts of same molecule (ex: in DNA, proteins, nucleic acids & other large molecules) -refer to attraction type in an electronegative atom like O, Fl, N -H is oxidized (electron # reduced) when bonds w/O -gives H2O many of its properties including high specific heat and heat of vaporization, solvent qualities, adhesiveness, cohesiveness, hydrophobic qualities, and its ability to float in solid form hydrogen bond