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54 Cards in this Set
- Front
- Back
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variable
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different factors in an experiment that can change
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constant variables
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variables that stay the same
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independent variable
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variable that changes
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dependent variable
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depends on the independent variable
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control
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baseline comparison
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accuracy
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how close the measurement is to the accepted value
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accepted value
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generally accepted measurement based on reliable sources.
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precision
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the consistency that something is measured at
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experimental value
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the measurement that you get
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error
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experiment value - accepted value
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% error
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|error|/ accepted x 100
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quantitative
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deals with #'s. need an instrument to measure
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qualitative
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uses words to describe
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significant measures
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all of known digits +1 that is estimated
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formula to convert Celsius to Kelvin
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k=c+273
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formula for density
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d=m/v
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density
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a physical property that does not change when mass changes.
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formula for volume
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V= 4/3 (pi r^3)
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formula for circumference
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C=(2 pi r)
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Democritus
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atomos; indestructible, made up all matter only one type of atom.
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Dalton
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took Democritus' theory and scientifically tested it.
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Dalton's 4 part Theory
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1. All elements made of small indivisible atoms.
2. all atoms of 1 elements are the same but atoms of diff elements are diff. 3. atoms can physically mix and chemically combine (in whole # ratios) 4. you cannot change one atom from one element into another element |
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atoms
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smallest particle that maintains its identity in a chemical reaction
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proton
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positive, relative mass: 1
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neutron
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neutral, relative mass: 1
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electron
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negative, relative mass 1/1840
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JJ Thompson
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discovered electron using cathode ray tube and developed plum pudding model
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Ernest Rutherford
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gold foil experiment
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isotopes
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2 atoms with the same number of protons but different number of electron.
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average atomic mass
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weighted avg. mass of all atomic mass of isotopes
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formula for average atomic mass
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(avg. mass iso. 1 * % abundance/100) + (avg, mass. iso. 2 * % abundance/100)
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quantum mechanical model
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based on the probability of location of an electron
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Schrodinger/ Heisenberg
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can't tell exactly where atoms are; found equation based on energy, electrons moved around the atom; fuzzy cloud.
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mechanics
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movement
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quantum
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amount of energy
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atomic orbital
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region of space where an electron could be found according to its energy
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Bohr
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planetary model; electron orbiting in a circular path based on energy level
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electron configuration
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where electron are locate in atom
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aufbau principle
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electrons occupy orbitals of lower energy 1st before moving on to higher ones
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pauli exclusion principle
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orbitals can have a max of 2 electrons and they must spin in opposite directions
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Hund's rule
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electrons on the same sub-level will try and have as many like spins as possible
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valence shell
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highest energy level of an atom; outer most electrons; determine elements properties.
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JW Dobereiner
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1829 organized elements into triads
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Mendeleev
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Arranged in order of atomic mass' left space of undiscovered elements
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Mosely
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1913; arranged according to atomic #
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periodic law
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when elements arranged in order there is periodic repetition of their physical and chemical properties
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metals
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ductile, malleable
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non-metals
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brittle
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metalloid
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share properties of both, can change properties
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atomic radius
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1/2 distance between 2 nuclei of a diatomic molecule
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ionization energy
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energy required to completely remove a valence electron from a gaseous atom
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electron negativity
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relative ability of an atom to attract a shared electron in a compound.
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ionic
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metal and non-metal
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covalent
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just non-metals
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