NEU GenChem 9/21-9/24 Toher
|Define significant figures (aka sig figs)|
Sig figs are used to determine which numbers in a measurement or calculation using measurement “count” or need to be reported for accuracy.
|How many rules for sig figs are there and what are they?|
There are 5 rules regarding sig figs. They are: 1: All non-zero digits are sig. 2: Zeros between non-zeros are significant. 3: Zeros which preceed non-zero digits are not significant. 4: Zeros at the end of a number with a decimal place anywhere in the number are significant. 5: Zeros at the end of of a number not specifically mentioned in scientific notation are not significant.
|Are there any exceptions to the rules of sig figs and if so, what are they?|
There is one exception which applies to rule #5. The base of the exception states that if there is a decimal place (such as 10.0) then both zeros are significant since the 0 typically would denote a rounded number.
|What are the rules for addition/subtraction of significant figures?|
|Sum/difference is reported to the number of decimal places as the measurement with the fewest decimal places. In the case of 15.8 – 14.73 3 sig figs would be used.|
|What is the rule for reporting sig figs in regards to multiplication/division?|
Like the addition/subtraction rule you simply take the least number of decimal places reported. Again, with a number of 3 sig figs and another of 4 the reported answer would have 3 sig figs.
Accuracy is defined as how close to the actual value a measurement is.
Precision is defined as how close together a set of measurements is.
|Define an atomic bond|
An atomic bond is defined as the “glue” which is the attraction force which holds atoms together.
|Define a covalent bond|
A covalent bond is defined as a bond in which electrons are shared between atoms (always a non-metal to another non-metal).
|Define an ionic bond|
|An ionic bond is defined as oppositely charged particles Coulombically attracted which is always between a metal and a non-metal (that is, always between a cation and an anion).|
|What are columns of the periodic table called?|
They’re called groups or families.
|What do metals tend to form?|
|Metals tend to form cations by electron loss (oxidation).|
|What to non-metals typically form?|
|Non-metals tend to form anions by electron gain (reduction).|
|In nomenclature, what does the prefix “per” denote?|
|It means that the highest amount of oxygen possible is present.|
|What does the prefix “hypo-” denote?|
|It indicates that the lowest amount of oxygen possible is present.|
|What is so special about CrAsPS?|
There is no per-ates and not hypo-ites. For example, PO4-3 becomes simply phosphate and PO3-3 becomes phosphite.
|If a compound ends in “-ide”, what will its acidic name become?|
|It will become hydro-ic acid (ex: hydrochloric acid).|
|CH3COO- or C2H3O2–|