Sig figs are used to determine which numbers in a measurement or calculation using measurement "count" or need to be reported for accuracy.

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.

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.

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.

An atomic bond is defined as the "glue" which is the attraction force which holds atoms together.

A covalent bond is defined as a bond in which electrons are shared between atoms (always a non-metal to another non-metal).

They're called groups or families.

There is no per-ates and not hypo-ites. For example, PO₄^-3 becomes simply phosphate and PO₃^-3 becomes phosphite.