Measurement Review CH 1 g: Students will perform mathematical manipulations with laboratory data.

Measurements Always estimate between the smallest two divisions on and instrument. If a measurement is exactly on a line always add a final zero. Measurements must have units.

Significant Figures How many significant figures are in each of the following? not Start counting at the first nonzero number and count the rest!

Identify each of the following as measurements of length, area, volume, mass, density, time or temperature. Give the significant figures in each. a.5 ns_______ ________sig figs b.25.5 mg_______ _______ sig figs c. 540 km 2 _______ _______

Calculations with measurements Do the following problems and round to the correct # of significant figures: 3.45 cm cm = 0.089g – g = 7.8 m x m = 8760 g / 8900 mL = Answers for + & - get rounded to the least number of decimal places! Answers for x & / get rounded to the least number of significant figures.!

(c) 2006, Mark Rosengarten Rounding with addition and subtraction Answers are rounded to the least precise place.

(c) 2006, Mark Rosengarten Rounding with multiplication and division Answers are rounded to the fewest number of significant figures.

Carry out the following calculations and round your answers to the correct number of significant figures. A g g g = _______________________________ B.( m)(347.0 m) = _______________________________ C.[(10.3 s)( m)] / [(1.68 s)(36.43)] = _______________________________

An ancient gold coin is 2.2 cm in diameter and 3.0 mm thick. It is a cylinder for with volume of 1.14 cm 3. What is the mass of gold in grams if gold has a density of 19.3 g/cm 3 ?

(c) 2006, Mark Rosengarten Metric Conversions Determine how many powers of ten difference there are between the two units (no prefix = 10 0 ) and create a conversion factor. Multiply or divide the given by the conversion factor. How many kg are in 38.2 cg? (38.2 cg) /( cg/kg) = km How many mL in dL? (0.988 dg) X (100 mL/dL) = 98.8 mL

Scientific Notation Ex. 3.2 x m Only one number in front of the decimal Units go on the outside of the number Positive exponent = move decimal to right Negative exponent = move decimal to left It is easiest to do calculations using scientific notation with a scientific calculator!! You are responsible for making sure you have one for the SOL test. They are not provided!!!

Accuracy vs Precision

Percent Error [Actual – Experimental] x100% Actual

Atom Review CH 2 a,b,&c: Students will understand the properties, location, and effect of each of the subatomic particles with respect to atomic number, mass number, isotopes, ions, atomic mass, and radioactivity. CH 2 h: Students will describe how the discoveries and insights related to the atom’s structure have changed the model of the atom over time.

Atomic structure 1802 – Dalton 1897 – Thompson 1911 – Rutherford Bohr 1920’s Quantum mechanical model Indestrucible Plum pudding Nuclear model Planetary Mathematical model electrons Dense + nucleus e- orbit e- treated as waves in a sea of surrounded by the e- can be anywhere positive charge e- in empty space nucleus

Why is Rutherford’s nuclear model of the atom more consistent with the results of the alpha particle scattering experiment that with Thomson’s “plum pudding” model ?

(c) 2006, Mark Rosengarten Rutherford Model The atom is made of a small, dense, positively charged nucleus with electrons at a distance, the vast majority of the volume of the atom is empty space. Alpha particles shot at a thin sheet of gold foil: most go through (empty space). Some deflect or bounce off (small + charged nucleus).

Niels Bohr Planetary model of the atom Electrons have certain energies which allow them to stay in certain orbits around the nucleus.

(c) 2006, Mark Rosengarten Quantum-Mechanical Model Electron energy levels are wave functions. Electrons are found in orbitals, regions of space where an electron is most likely to be found. You can’t know both where the electron is and where it is going at the same time. Electrons buzz around the nucleus like gnats buzzing around your head.

Atomic Symbol Isotope: element name – mass # ex. Carbon - 14 #p #p + #n#p - #e Element symbol

Isotopes 52 Crp:n:e: 13 N -3 p:n:e: 23 Na + p:n:e: 34 p38n36e Copper 64 p:n:e:

Atomic Mass An element has two naturally occurring isotopes as given in the table. What is the average atomic mass of the element? What is the element? Mass (amu) % abunda nce % % Remember you are basically averaging the mass of 100 atoms!

(c) 2006, Mark Rosengarten Nuclear Chemistry

Half-Life Length of time required for ½ of an atom of a radioactive substance to decay # HL = total time /half life Remaining mass = Mass 2 #HL Ex. Manganese-56 is a beta emitter with a half life of 2.6 hours. What is the mass of the Manganese-56 in a 1mg sample after 10.4 hours?

(c) 2006, Mark Rosengarten a) Write the balanced nuclear reaction for iodine 131 undergoing beta decay. b) How many grams of a 10.0 gram sample of I-131 (half-life of 8 days) will remain in 24 days?