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**preview**shows pages 1-2. to view the full**8 pages of the document.**Chemistry Topic 1 –

Measurements and Math in

Chemistry

Standard Notation (All values)

oThe standard notation includes actual numbers in its entirety.

The rest mass of an electron

0.000 000 000 000 000 000 000 000 000 000 910 9 kg

Exponential Notation

oConsidering standard deviation there are two components;

The significand (mantissa)

•The non-zero portion

The exponent

•The power of 10 by which you multiply the mantissa to give

the whole value

The speed of light

299 800 200 m/s

The significand: 2998

Exponent: 10^5 - Therefore the exponential notation is 2998 x 10^5

Scientific Notation

oThe significand must be >1 and <10

Only 1 digit before the decimal point but as many digits that are

required after the decimal point

oA positive exponent means the value is larger than the significand implies

(decimal jumps left)

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oA negative exponent means the value is smaller than the significand

implies (decimal jumps right)

0.000 239 = 2.39 x 10^-4 Number becomes smaller

239 0000 = 2.39 x 10^5 Number becomes larger

TRAILING ZEROS: Any zeros left behind the significand

2.99 800 000 x10^8 m/s becomes 2.998 x 10^8 m/s

The idea is to reduce all of the zeros after the significand.

The difference between the exponential and scientific notation is the placement of the

decimal point (scientific has only one digit before the decimal point).

SIGNIFICANT FIGURES: The amount of digits that are considered significant in a final

value. The number of digits that indicate precision of a measured value.

Rules for SIGFIG;

Indicate how precisely a value is measured

oPRECISION: Measure of how consistent (close) a series of measured

values are

oACCURATE: Measure of how close to the true value a series of

measured values are

Do not show accuracy

Only apply to measured values

Things to remember about SIGFIG;

All non-zero are significant

Any zeros between two SIGFIGS are significant (209 = 3 SF)

Leading zeros are not significant

Trailing zeros are significant or not depending on the placement of the decimal.

(The decimal must be present for these zeros to be significant)

21.895 = 5 2980 = 3

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0.001 244 = 4 2980. = 4

1001 = 4 6.00 = 3

3000 = 1

When rounding to SF in a completed calculation the result is different depending on the

type of calculation.

1. Multiplication and Division

Round to a number of SF equal to the input value with the fewest SF

( 24 )(8.314) = 0.021 149 386

(293)(32.2)

= 0.02

Round to the lowest number of SF

2. Addition and Subtraction

Round to the number of SF such that the lowest number of decimal places is

preserved.

112.2765 + 222.7= 334.9765 round to 1 decimal point

= 335.0

For addition and subtraction in scientific notation, all values should be converted

to all have the same exponential value, then the rule of decimal places applies.

If you make the exponent LARGER, the significand gets SMALLER

If you make the exponent SMALLER, the significand gets LARGER

3. Logarithmic

Rules;

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