Zeros, significant figures

A recorded volume of 2.8 L represents two significant figures. If this same volume were written 0.028 m3, it would still contain only two significant figures. Zeroes appearing as the first digits of a number are not significant, since they merely locate the decimal point. 

Two significant figures Zeroes to the left of the first nonzero digit are not significant. 

Two significant figures Zeroes between nonzero digits are significant. 

A chemical bond exhibiting 100% covalent character and 0% ionic character occurs between identical nonmetals atoms in which the difference in electronegativity (AEN) is zero. An example is the H-H bond. There are atoms with essentially the same electronegativity, e.g. N and Cl both have an electronegativity equal to 3.0 to 2 significant figures, so the N-Cl bond would exhibit close to 100% covalent character and 0% ionic character . 

Zeros between significant figures (captive zeros) are significant. 80601 = 5 s.f. 10.001 =... 

A zero, when placed between digits, is considered to be significant. For example, 4.005 has 4 significant figures. 

A zero, when used only to locate the decimal point, is not considered significant. For example, 0.00025 has only 2 significant figures. 

Balances with few such significant figures to the right of the decimal point (zero to three) are often referred to as ordinary balances or top-loading balances (precision is 100 to 1 mg). A top-loading balance is an electronic ordinary balance with a pan on the top, as shown in Figure 3.3. The electronic... 

Any zero located between two significant figures is significant. 

The reduced mass ratios agree exactly with Aston s to the five significant figures reported by Aston. An interesting result obtained in this study, where there was no longer any question abut zero-point energy, is the electronic isotope effect reported as 0.33 0.08 cm-1, a result which appears much more satisfactory than that obtained earlier by Mulliken. 

Alignment, numbers Align numbers on the decimal. Include a leading zero for numbers <1 (e.g., 0.5). Include zeroes to the right of the decimal point only if they are significant figures (e.g., 10.0 when the tenths place is known). 

One or more final zeros (zeros that end the measurement) used after the decimal point are significant. So 1.760 has four significant figures, and 1.7600 has five significant figures. The number 0.0001200 has only four significant figures because the first zeros are not final. 

Exercise 3.2. Verify that the net charge at each carbon atom of each of the neutral ring systems shown in Figure 5.3 is zero (to two significant figures). 

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